On June 21, 2024 I started a thread on reddit with the following question: &ldquo;What would you improve about Django framework?&rdquo;. The response from the community was immediate and the conversation quickly filled up with suggestions on how to improve Django framework, ranging from modest to quite radical. I summarize the results below.&#xA;<a href="https://htmx.org/img/memes/20yearold.png" aria-label="HTMX Meme">&#xA;&#xA;<figure>&#xA; <img class="md-image" loading="lazy" src="https://htmx.org/img/memes/20yearold.png" alt="HTMX Meme"/>&#xA; <figcaption>HTMX meme</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;<h2 id="would-type-hints-improve-django-framework">Would type hints improve Django Framework?</h2>&#xA;This was the comment that received the most support from the community. Although Python already has optional Type Hints since version 3.5, it seems that implementing them for the purpose of modernizing Django Framework does not seem to be a priority.&#xA;<a href="images/comment-with-more-support-on-how-to-improve-django.png" aria-label="Comment with more support on how to improve Django">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="592" height="140" loading="lazy" src="images/comment-with-more-support-on-how-to-improve-django.png" alt="Comment with more support on how to improve Django"/>&#xA; <figcaption>Comment with more support on how to improve Django</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;The popularity of type hints is such that some users who consider them a significant improvement to the framework have developed &#xA;&#xA;<a class="markdown-link" href="https://github.com/typeddjango/django-stubs" rel="noopener nofollow" target="_blank">an external library, called django-stubs</a>&#xA;, which aims to revamp the Django Framework with type hints.&#xA;<h3 id="type-hints-have-already-been-evaluated-and-rejected">Type hints have already been evaluated and rejected.</h3>&#xA;However, according to reddit users, there is not much interest from the code maintainers to incorporate these changes as part of the code. There have even been &#xA;&#xA;<a class="markdown-link" href="https://github.com/django/deps/pull/65" rel="noopener nofollow" target="_blank">proposals to incorporate type hints into the official Django repository</a>&#xA;, but these changes have been dismissed, probably because they consider the typing to be a contradiction to the nature of Python as a dynamic language.&#xA;&#xA;&#xA;&#xA; &#xA; &#xA; In case you don&#39;t know what type hints are, type hints allow you to declare the type of a variable, argument, or the return value of a function to make it easier to identify bugs or unwanted behavior. Think of Python type hints as Python&#39;s Typescript, or as optional static typing in your favourite compiled language, such as C, C&#43;&#43;, or Rust.&#xA;&#xA;&#xA;<h2 id="use-a-custom-user-model-instead-of-the-normal-user-model">Use a custom User model instead of the normal User model.</h2>&#xA;The second comment that received the most support states that customizing Django&rsquo;s User model is quite complicated, especially if done mid-project, more specifically changing Django&rsquo;s default login type from user to email.&#xA;<a href="images/custom-user-model-to-improve-django.png" aria-label="Second comment with most support on how to improve Django">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="793" height="136" loading="lazy" src="images/custom-user-model-to-improve-django.png" alt="Second comment with most support on how to improve Django"/>&#xA; <figcaption>Second comment with most support on how to improve Django</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;Although there are multiple ways to &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/how-to-customize-the-user-model-in-django/">customize the User model in Django</a>&#xA;, such as using a proxy model, or inheriting from AbstractUser, some users find that solution a little bit &ldquo;hackish&rdquo;.&#xA;&#xA;&#xA;&#xA; &#xA; &#xA; In case you don&#39;t know, Django uses by default the *username* from its *User* model, in combination with the password, to log in a user. But the current trend in web development is to use email directly.&#xA;&#xA;&#xA;<h2 id="rest-support-in-django-without-third-party-libraries">REST support in Django without third-party libraries.</h2>&#xA;Despite the fact that Django has one of the best libraries to create an application that meets the &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/basic-characteristics-of-an-api-rest-api/">basic features of a REST API</a>&#xA;; yes, I&rsquo;m talking about DRF (Django Rest Framework). The reddit users consider that Django should provide support for REST APIs &ldquo;out of the box&rdquo;, as a native part of the framework.&#xA;The above seems to me an interesting proposal but I also understand that, despite the maturity of REST, giving it preference over the rest of APIs, such as &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/unleash-your-apis-potential-with-grpc-and-protobuffers/">the modern Google gRPC</a>&#xA;, SOAP, or some API that has not yet emerged, can be considered as a rather risky step by the Django committee. Yes, even if there are complete REST-based libraries, such as &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/fastapi-tutorial-the-best-python-framework/">FastAPI</a>&#xA;.&#xA;<h2 id="read-environment-variables-in-django-without-third-party-libraries">Read environment variables in Django without third-party libraries</h2>&#xA;Django can read environment variables directly using Python&rsquo;s os library, but other libraries, such as &#xA;&#xA;<a class="markdown-link" href="https://django-environ.readthedocs.io/en/latest/" rel="noopener nofollow" target="_blank">django-environ</a>&#xA;, have been developed to provide a more robust solution, where it reads directly from an .env file and where the absence of an environment variable will crash the application, ensuring that a Django application cannot start if even one environment variable is missing, which is what I imagine the developers of this popular forum want.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">import os&#xA;&#xA;os.environ[&#34;VARIABLE&#34;]&#xA;</code></pre></div><h3 id="other-frameworks-that-do-read-environment-variables">Other frameworks that do read environment variables</h3>&#xA;Contrary to Django, frameworks like Nextjs load environment variables by default and even allow you to make some of them public with the NEXT_PUBLIC_ prefix, but in the case of Django you need to load the required variables manually or use a third-party library.&#xA;<h2 id="django-native-integration-with-frontend">Django native integration with frontend</h2>&#xA;It&rsquo;s no secret that the frontend has received a gigantic boost in recent years, libraries like React, Vue, Svelte and others have taken a remarkable prominence in recent years, completely changing the paradigm of client-side development. Django has been agnostic about the separation between Backend and Frontend, probably because &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/why-should-you-use-django-framework/">Django is a monolithic framework</a>&#xA; (and I mean that in a non-pejorative way).&#xA;I guess some users consider that Django should not lag behind and should provide integration options with some frontend libraries to favor the reactivity of the applications, as Nextjs does for some time, since it allows you to select the frontend library to work with and even takes care of the minification and tree-shaking of the code through Webpack or its experimental compiler written in Rust.&#xA;<h3 id="improving-django-with-htmx">Improving Django with HTMX</h3>&#xA;It seems to me that Django already does an excellent job with its template system and that it combines perfectly with &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/django-and-htmx-modern-web-apps-without-writing-js/">libraries like HTMX</a>&#xA;, to take advantage of all the power of hypertext without the need to incorporate Javascript to the project.&#xA;<a href="https://htmx.org/img/memes/original.png" aria-label="Javascript delusion according to HTMX">&#xA;&#xA;<figure>&#xA; <img class="md-image" loading="lazy" src="https://htmx.org/img/memes/original.png" alt="Javascript delusion according to HTMX"/>&#xA; <figcaption>Javascript delusion according to HTMX</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;Without more to add I leave the link to the discussion if you want to see the rest of &#xA;&#xA;<a class="markdown-link" href="https://www.reddit.com/r/django/comments/1dlj5n6/what_would_you_improve_about_django_framework/" rel="noopener nofollow" target="_blank">suggestions on how to improve Django Framework.</a>&#xA;&#xA;<h2 id="other-suggestions-on-how-to-improve-django-framework">Other suggestions on how to improve Django framework</h2>&#xA;Among the other suggestions I would like to highlight the following, as they received minor support or were mentioned multiple times throughout the thread:&#xA;<ul>&#xA;<li>Better form handling</li>&#xA;<li>Better static content handling with emphasis on most popular frontend frameworks</li>&#xA;<li>Out of the box support for queues</li>&#xA;<li>Hot reload of the browser</li>&#xA;<li>Basic CRUD boilerplate generator</li>&#xA;<li>Models&rsquo; auto prefetch of their related models.</li>&#xA;</ul>&#xA;<h3 id="suggestions-that-ended-up-being-third-party-libraries">Suggestions that ended up being third party libraries</h3>&#xA;<ul>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://github.com/typeddjango/django-stubs/" rel="noopener nofollow" target="_blank">Static types and type inference for Django framework</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://docs.iommi.rocks/en/latest/" rel="noopener nofollow" target="_blank">Form handling for Django with steroids</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://noumenal.es/neapolitan/" rel="noopener nofollow" target="_blank">CRUD capabilities for Django out of the box</a>&#xA;</li>&#xA;</ul>&#xA;

On June 21, 2024 I started a thread on reddit with the following question: &ldquo;What would you improve about Django framework?&rdquo;. The response from the community was immediate and the conversation quickly filled up with suggestions on how to improve Django framework, ranging from modest to quite radical. I summarize the results below.&#xA;HTMX meme Would type hints improve Django Framework? This was the comment that received the most support from the community.

How to improve Django Framework?

I wrote a series of entries trying to serve as a guide an introduction to learn the Go programming language. This tutorial requires you to know at least the basis of programming, so it&rsquo;s probably a good idea to read this only if you&rsquo;re learning Go as your second or third programming language. This content goes from Go&rsquo;s basic syntax to advances uses as signal catching or containerization.&#xA;<h2 id="go-language-introduction-and-basic-syntax">Go language introduction and Basic Syntax</h2>&#xA;Introduction to the Go programming language, native data types, variables, the controversy around this language, the good, the bad, the ugly and even a glimpse to its popular, and sometimes hated, mascot.&#xA;&#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-programming-language-introduction-to-variables-and-data-types/">&#xA; &#xA; &#xA; Go, coding language, introduction to variables and data types &#xA; &#xA; &#xA;&#xA;</a>&#xA;&#xA;How to create go functions and pass arguments to them, along with the basis of the fmt package used to print text on the screen&#xA;&#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-functions-arguments-and-the-fmt-package/">&#xA; &#xA; &#xA; Go: functions, arguments and the fmt package &#xA; &#xA; &#xA;&#xA;</a>&#xA;&#xA;Master the different type of loops that exist in go, learn how to use flow control to execute your code conditionally and learn about they break, continue and defer clauses.&#xA;&#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-cycles-or-loops-for-break-continue-defer-if-and-else/">&#xA; &#xA; &#xA; Go: loops for, break, continue, defer, if and else &#xA; &#xA; &#xA;&#xA;</a>&#xA;&#xA;Create array and slices and know their differences and how to iterate over them correctly using range.&#xA;&#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-slices-and-arrays-basic-characteristics-and-most-common-uses/">&#xA; &#xA; &#xA; Go: slices and arrays, basic characteristics and most common uses &#xA; &#xA; &#xA;&#xA;</a>&#xA;&#xA;Learn how do map or dictionaries work internally, the different ways to create them and how to iterate over them using range.&#xA;&#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/golang-maps-or-dictionaries/">&#xA; &#xA; &#xA; Golang maps or dictionaries &#xA; &#xA; &#xA;&#xA;</a>&#xA;&#xA;Read about the main differences that exist between string, runes and bytes in go, how they work internally and their main related methods.&#xA;&#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-string-runes-and-bytes-explained/">&#xA; &#xA; &#xA; Go: string runes and bytes explained &#xA; &#xA; &#xA;&#xA;</a>&#xA;&#xA;<h2 id="go-programming-language-tutorial-object-oriented-programming">Go Programming Language Tutorial: Object oriented programming</h2>&#xA;Go doesn&rsquo;t have classes, but you can emulate OOP features (polimorfism, inheritance and encapsulation) using go structs.&#xA;&#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-structs-inheritance-polymorphism-and-encapsulation/">&#xA; &#xA; &#xA; Go: Structs, inheritance, polymorphism and encapsulation &#xA; &#xA; &#xA;&#xA;</a>&#xA;&#xA;How to handle and import and reference packages and modules in go.&#xA;&#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-package-import-and-module-management/">&#xA; &#xA; &#xA; Go: package import and module management &#xA; &#xA; &#xA;&#xA;</a>&#xA;&#xA;<h2 id="go-programming-language-tutorial-concurrency-and-corroutines">Go Programming Language Tutorial: Concurrency and Corroutines</h2>&#xA;The feature that makes go stand out: concurrency and goroutines, learn how to create and handle them.&#xA;&#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-introduction-to-goroutines-and-concurrency/">&#xA; &#xA; &#xA; Go: introduction to goroutines and concurrency &#xA; &#xA; &#xA;&#xA;</a>&#xA;&#xA;Here I explain you how to communicate goroutines through channels and the main principles to take care of when working with concurrent code.&#xA;&#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-use-of-channels-to-communicate-goroutines/">&#xA; &#xA; &#xA; Go: use of channels to communicate goroutines &#xA; &#xA; &#xA;&#xA;</a>&#xA;&#xA;Understand the concept of deadlocks in the context of working with goroutines, how to avoid them and what causes this problem.&#xA;&#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-channels-understanding-the-goroutines-deadlocks/">&#xA; &#xA; &#xA; Go: channels, understanding the goroutines deadlocks &#xA; &#xA; &#xA;&#xA;</a>&#xA;&#xA;The basics of race conditions when working with concurrent code and how to prevent them. Create race condition resistant code using mutexes in Go&#xA;&#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-race-conditions-on-goroutines-and-mutexes/">&#xA; &#xA; &#xA; Go: race conditions on goroutines and mutexes &#xA; &#xA; &#xA;&#xA;</a>&#xA;&#xA;<h2 id="go-programming-language-tutorial-testing-and-logging">Go Programming Language Tutorial: Testing and Logging</h2>&#xA;The basis of go testing and coverage capabilities.&#xA;&#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-basic-testing-and-coverage/">&#xA; &#xA; &#xA; Go: basic testing and coverage &#xA; &#xA; &#xA;&#xA;</a>&#xA;&#xA;How to profile and examine code performance using go.&#xA;&#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-profiling-or-basic-profiling-of-cpu-usage/">&#xA; &#xA; &#xA; Go: profiling or basic profiling of CPU usage &#xA; &#xA; &#xA;&#xA;</a>&#xA;&#xA;How to use the default logging library in go programming language.&#xA;&#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/logging-with-the-standard-library-in-go/">&#xA; &#xA; &#xA; Logging with the standard library in Go &#xA; &#xA; &#xA;&#xA;</a>&#xA;&#xA;<h2 id="go-applications">Go Applications</h2>&#xA;How to catch signals and process them in go to end your code execution in an elegant and safe way.&#xA;&#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-handling-signals-for-closing-applications/">&#xA; &#xA; &#xA; Go: Handling Signals for Closing Applications &#xA; &#xA; &#xA;&#xA;</a>&#xA;&#xA;Learn how to handle SQL migrations using go&rsquo;s migrate library&#xA;&#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-migration-tutorial-with-migrate/">&#xA; &#xA; &#xA; Go Migration Tutorial with migrate &#xA; &#xA; &#xA;&#xA;</a>&#xA;&#xA;The basis of go&rsquo;s reflection library and how to create flexible code that deals with unknown types&#xA;&#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-with-reflect-discover-how-reflect-can-boost-your-programs-flexibility/">&#xA; &#xA; &#xA; Go with Reflect: Boost Your Code&#39;s Flexibility &#xA; &#xA; &#xA;&#xA;</a>&#xA;&#xA;Did you know that Docker is written in Go? Have you ever wondered how does a docker container works internally? Well I explain all the concepts that you need to know here in order to create your own containerization technology.&#xA;&#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/how-does-a-docker-container-work-internally/">&#xA; &#xA; &#xA; How Does a Docker Container Work Internally? &#xA; &#xA; &#xA;&#xA;</a>&#xA;&#xA;I explain the worker pool design pattern in go and how to take advantage of Go&rsquo;s concurrency and this design pattern to limit the amount of resources that your application uses.&#xA;&#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/worker-pool-design-pattern-explanation/">&#xA; &#xA; &#xA; Worker Pool Design Pattern Explanation &#xA; &#xA; &#xA;&#xA;</a>&#xA;&#xA;

I wrote a series of entries trying to serve as a guide an introduction to learn the Go programming language. This tutorial requires you to know at least the basis of programming, so it&rsquo;s probably a good idea to read this only if you&rsquo;re learning Go as your second or third programming language. This content goes from Go&rsquo;s basic syntax to advances uses as signal catching or containerization.&#xA;Go language introduction and Basic Syntax Introduction to the Go programming language, native data types, variables, the controversy around this language, the good, the bad, the ugly and even a glimpse to its popular, and sometimes hated, mascot.

Go Programming Language Tutorial

Sometimes we want to put an email on a website but without exposing it to be read by some random bot that includes us in an advertising list, reminding us of our problems to start a physical relationship with the two mature women who live less than two kilometers away. And since we don&rsquo;t want that, there are several things we can do to solve this and here I present some solutions, the last one is the one I usually use and also my favorite.&#xA;<a href="images/prince-from-nigeria-scam.jpg" aria-label="Classic scam email from a Prince from Nigeria">&#xA;&#xA; <img class="md-image" width="750" height="750" loading="lazy" src="images/prince-from-nigeria-scam.jpg" alt="Classic scam email from a Prince from Nigeria"/>&#xA;&#xA;</a>&#xA;<h2 id="convert-your-email-to-an-image-and-avoid-spam">Convert your email to an image and avoid spam</h2>&#xA;This way to protect your email address requires no detailed explanation, just turn your email into an image and place it, your address will be safe from any text scraping bot, but it will be vulnerable to any bot with &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/ocr-with-tesseract-python-and-pytesseract/">OCR (Optical Character Recognition) capabilities, bots with pytesseract for example</a>&#xA;, which I predict will be few if any.&#xA;<a href="images/email-image.jpg" aria-label="email address in an image">&#xA;&#xA; <img class="md-image" width="200" height="55" loading="lazy" src="images/email-image.jpg" alt="email address in an image"/>&#xA;&#xA;</a>&#xA;The disadvantage of this approach is that the person who wants to send you an email will have to type it in manually, as they can&rsquo;t copy-paste, and you know that every extra step adds friction to the conversion process.&#xA;<h2 id="use-a-different-email-notation">Use a different email notation</h2>&#xA;Instead of using the classic format like &#xA;&#xA;<a class="markdown-link" href="mailto:my@email.com">my@email.com</a>&#xA;, change it to something less obvious to bots, like my [at] email [dot] com, this way your address won&rsquo;t be detected as an email by less sophisticated bots and if someone wants to send you an email just replace the at and dot with their corresponding symbols.&#xA;A pretty balanced option in my opinion, although if it becomes popular I&rsquo;m sure my blue pill factory ambassadors will find a way to get the valuable information they need.&#xA;<h2 id="ask-the-user-to-generate-the-email-with-extra-information">Ask the user to generate the email with extra information</h2>&#xA;Another way is not to put the email directly, but a hint as to how it can be deduced, for example if the site is called lain.com you can write a text as a hint that says something like:&#xA;<blockquote>&#xA;&ldquo;My email is the name that appears in the url and is a google email address&rdquo;.&#xA;</blockquote>&#xA;With that it will understand that the address is &#xA;&#xA;<a class="markdown-link" href="mailto:lain@gmail.com">lain@gmail.com</a>&#xA;.&#xA;Just try not to complicate things too much here, don&rsquo;t overestimate the deductive capabilities of the average web surfer.&#xA;<h2 id="use-a-form-instead-of-an-email-address">Use a form instead of an email address</h2>&#xA;Another option is to completely forget about placing your email and use a form instead, this way your email will be safe from spam and you can direct the emails to a unique account that you use for that single purpose.&#xA;<h3 id="protect-your-form-from-spam-with-a-captcha">Protect your form from spam with a captcha</h3>&#xA;Of course some bots will try to fill out the form to send you advertisements but you can always use &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/my-analysis-of-anti-bot-captchas-and-their-advantages-and-disadvantages/">a strong captcha to protect yourself from spam</a>&#xA;&#xA;<a href="images/captcha-frieren-fern.webp" aria-label="Anime captcha image from Freiren">&#xA;&#xA; <img class="md-image" width="500" height="736" loading="lazy" src="images/captcha-frieren-fern.webp" alt="Anime captcha image from Freiren"/>&#xA;&#xA;</a>&#xA;<h3 id="use-custom-email-spam-filters">Use custom email spam filters</h3>&#xA;If you don&rsquo;t want to use captchas you can leave the responsibility of recognizing spam to your email provider&rsquo;s filters, or use a customized filter created by you and combine it with some instruction like:&#xA;<blockquote>&#xA;&ldquo;To know that you are not a bot, please include the word jelly bean in your email. ” *.&#xA;</blockquote>&#xA;Now just set up your filter and automatically delete all emails that do not meet this condition.&#xA;<h2 id="avoid-spam-generating-your-email-dynamically">Avoid spam generating your email dynamically</h2>&#xA;This is my favorite, to achieve this we can use some kind of simple encryption, or even base64, encode our email address in base64 and then decode it in the frontend dynamically using Javascript, this way the bots will only see a bunch of numbers and letters in the source code, to read the email they will need to render the page with javascript enabled, which eliminates those bots that only read the source code of the response.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-javascript" data-lang="javascript">// this comes from the server&#xA;const encodedEmail = &#34;eW91YXJlY3VyaW91c0BpbGlrZWl0LmNvbQ==&#34;&#xA;// atob decodes from base64&#xA;const decodedEmail = atob(encodedEmail)&#xA;</code></pre></div>For an ordinary user, the email will be displayed as if it were included in the source code of the page.&#xA;<h3 id="generate-an-email-dynamically-with-user-interaction">Generate an email dynamically with user interaction.</h3>&#xA;To make this protection method more secure we can delay the decoding until the user presses a button, scrolls, makes a mouse movement or even use the intersection observer to decode it only if the email is on screen; the limit is your imagination.&#xA;

Sometimes we want to put an email on a website but without exposing it to be read by some random bot that includes us in an advertising list, reminding us of our problems to start a physical relationship with the two mature women who live less than two kilometers away. And since we don&rsquo;t want that, there are several things we can do to solve this and here I present some solutions, the last one is the one I usually use and also my favorite.

How to avoid spam when putting an email on a website?

This is my analysis of some of the most popular captcha options out there and my opinion as a user on their advantages and disadvantages, this analysis includes google recaptcha, sliding captchas, simple questions, letter and number recognition and the most bot resistant captcha I know of.&#xA;<h2 id="google-recaptcha-and-similar">Google recaptcha and similar</h2>&#xA;I&rsquo;m sure you already know this one, as it&rsquo;s the most common, and probably the most popular captcha out there. Google&rsquo;s and Cloudflare&rsquo;s stand out here.&#xA;<a href="images/recaptcha-open-ai-sam-altman.jpg" aria-label="Recaptcha elon musk">&#xA;&#xA; <img class="md-image" width="402" height="603" loading="lazy" src="images/recaptcha-open-ai-sam-altman.jpg" alt="Recaptcha elon musk"/>&#xA;&#xA;</a>&#xA;The inner workings of this type of captcha are very complex and are based on recognizing patterns in a user&rsquo;s traffic and probably analyzing them against the large amount of information they have collected over the years to then decide if there is a significant probability that a user is a bot.&#xA;<a href="images/recaptcha-style-captcha.gif" aria-label="Recaptcha style captcha solved">&#xA;&#xA; <img class="md-image" width="576" height="170" loading="lazy" src="images/recaptcha-style-captcha.gif" alt="Recaptcha style captcha solved"/>&#xA;&#xA;</a>&#xA;For a hypothetical user it is usually enough to click the checkbox and that&rsquo;s it, but if we don&rsquo;t convince the captcha algorithm, it will ask us to <del>train its AI models for free</del> a couple of more tests in which we will have to identify images.&#xA;The only disadvantage I see to this type of captcha is that by using it we are feeding google with more information about the users of our website. And you may not mind that google collects more information, if this is the case I can only bring up the Cambridge Analytica scandal.&#xA;My veredict:&#xA;<ul>&#xA;<li>Security: 9</li>&#xA;<li>User friendly: 8 wiithout image recognition and 5 with it</li>&#xA;</ul>&#xA;<h2 id="basic-questions-captchas">Basic questions captchas</h2>&#xA;There are more primitive captcha options, but no less effective such as a simple question: How much is 7 + 2?.&#xA;To solve it, just read it and enter the correct result.&#xA;<a href="images/simple-question-captcha.png" aria-label="Simple Question captcha example">&#xA;&#xA; <img class="md-image" width="459" height="265" loading="lazy" src="images/simple-question-captcha.png" alt="Simple Question captcha example"/>&#xA;&#xA;</a>&#xA;I find this kind of captchas super practical to deal with most of the bots that blindly roam the internet, and they are also minimally invasive for the user.&#xA;Their disadvantage, it seems to me, is their weakness against a personalized attack, since it will be enough for a human to enter the website, read the question and adapt the code to his convenience.&#xA;I also consider that, with the &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/the-rise-and-fall-of-the-ai-bubble/">rise of artificial intelligence</a>&#xA; they will become obsolete, since it is enough to ask the AI to read the label of the input and generate an appropriate response.&#xA;My veredict:&#xA;<ul>&#xA;<li>Security: 6</li>&#xA;<li>User friendly: 8</li>&#xA;</ul>&#xA;<h2 id="character-recognition-captchas">Character recognition captchas</h2>&#xA;Another popular alternative to simple questions is to use an image with numbers and letters and ask the user to identify them and place them in the appropriate field, these letters are distorted in some way to make them unrecognizable to bots.&#xA;<a href="images/letters-and-numbers-captcha.png" aria-label="letters and number captcha">&#xA;&#xA; <img class="md-image" width="193" height="61" loading="lazy" src="images/letters-and-numbers-captcha.png" alt="letters and number captcha"/>&#xA;&#xA;</a>&#xA;This type of captcha tends to be quite invasive for users and can ruin the web experience. On top of that, I don&rsquo;t consider them particularly useful for dealing with bots, there are even tutorials on &#xA;&#xA;<a class="markdown-link" href="https://medium.com/lemontech-engineering/breaking-captchas-from-scracth-almost-753895fade8a" rel="noopener nofollow" target="_blank">how to solve these captchas almost automatically</a>&#xA;.&#xA;If you don&rsquo;t want to read the whole article I&rsquo;ll summarize it for you, it basically consists of transforming the image with image editing software to highlight the characters and then using &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/ocr-with-tesseract-python-and-pytesseract/">an OCR, like tesseract in combination with one of its bindings, like pytesseract</a>&#xA;, to read them.&#xA;Also take into account that many of these modern captchas also consider how you fill in the text input, i.e. they expect you to fill it in like a human, bringing the mouse pointer towards them and typing letter by letter at regular intervals.&#xA;My veredict:&#xA;<ul>&#xA;<li>Security: 7</li>&#xA;<li>User friendly: 6</li>&#xA;</ul>&#xA;<h2 id="invisible-input-field-captchas">Invisible input field captchas</h2>&#xA;This type of captchas relies on CSS to create invisible input fields to the user, that a bot will detect and try to fill, so they can then be identified by the server and be discarded or blocked.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-html" data-lang="html">&lt;form method=&#34;post&#34;&gt;&#xA; &lt;!-- Hide this with css instead --&gt;&#xA; &lt;input type=&#34;text&#34; name=&#34;email&#34; style=&#34;display:none;&#34;&gt;&#xA; &lt;!-- real field --&gt;&#xA; &lt;input type=&#34;text&#34; name=&#34;real_email&#34;&gt;&#xA; &lt;input type=&#34;submit&#34;&gt;&#xA;&lt;/form&gt;&#xA;</code></pre></div>This type of captchas seem to me perfect for the user, as they are completely invisible to the user, however they suffer from custom attacks where a human detects the strategy and simply modifies the bot to not fill those now visible fields.&#xA;My veredict:&#xA;<ul>&#xA;<li>Security: 7</li>&#xA;<li>User friendly: 9</li>&#xA;</ul>&#xA;<h2 id="slider-captchas">Slider captchas</h2>&#xA;I&rsquo;ve seen these types of captchas on Tik Tok mainly, but you usually don&rsquo;t find them so easily on the web.&#xA;<a href="images/slider-captcha-example.gif" aria-label="Slider captcha">&#xA;&#xA; <img class="md-image" width="616" height="300" loading="lazy" src="images/slider-captcha-example.gif" alt="Slider captcha"/>&#xA;&#xA;</a>&#xA;I consider slider captchas to be one of the most balanced options out there, they are quick to solve and quite secure, although I doubt they are totally secure against all bots, mainly those that try to simulate users&rsquo; mouse movements.&#xA;I have never broken one of these captchas, but I imagine that using image processing as in the example above and some mouse movement emulation tool, it should not be impossible. Which brings me to the last type of captcha.&#xA;My veredict:&#xA;<ul>&#xA;<li>Security: 8</li>&#xA;<li>User friendly: 8</li>&#xA;</ul>&#xA;<h2 id="captchas-that-are-safe-and-almost-impossible-to-solve">Captchas that are safe and almost impossible to solve</h2>&#xA;This is probably the most secure, and also the most invasive captcha I&rsquo;ve seen. It is found on the most popular English-speaking image board to date and I have not seen it anywhere else.&#xA;<a href="images/4chan-captcha.gif" aria-label="4chan impossible captcha gif">&#xA;&#xA; <img class="md-image" width="494" height="186" loading="lazy" src="images/4chan-captcha.gif" alt="4chan impossible captcha gif"/>&#xA;&#xA;</a>&#xA;I want you to notice how sophisticated this captcha is. It is a simple box where it shows some scribbles in black and white, completely illegible and in the background an image that, when sliding the slider, overlaps with the background image, revealing the captcha before your eyes.&#xA;This gradient formed between the &ldquo;fake&rdquo; captchas and the &ldquo;real&rdquo; one confuses any character recognition software, making it completely useless.&#xA;In addition, this captcha requires interactivity from the user, as it requires the slider to be slid carefully, which rules out all those headless bots.&#xA;On the other hand, it has the disadvantage of being invasive for the user, completely interrupting the browsing experience. Furthermore, I would venture to say that this captcha also gives a lot of false positives; I myself am unable to accurately read the characters that appear there and I&rsquo;m not a bot, am I?&#xA;My veredict:&#xA;<ul>&#xA;<li>Security: 10</li>&#xA;<li>User friendly: 2</li>&#xA;</ul>&#xA;In defense of this captcha, I will say that it is a necessary evil on a website where it is not necessary to register to post, home of what was (or is) one of the most famous hacker groups: Anonymous and where illegal material was (or is) distributed, pictures and videos so cursed that will make you doubt if humanity deserves to share this planet with the rest of animals.&#xA;I definitely do not recommend this type of captcha unless you have a website with similar characteristics, in such case my deepest condolences.&#xA;

This is my analysis of some of the most popular captcha options out there and my opinion as a user on their advantages and disadvantages, this analysis includes google recaptcha, sliding captchas, simple questions, letter and number recognition and the most bot resistant captcha I know of.&#xA;Google recaptcha and similar I&rsquo;m sure you already know this one, as it&rsquo;s the most common, and probably the most popular captcha out there.

My Analysis Of Anti Bot Captchas and their  Advantages And Disadvantages

A few years ago, I migrated my website a couple of times, first from Wordpress to Frontity (A wordpress framework in React) and then from Frontity to a &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/digital-ocean-analysis-and-my-experience-as-a-user/">Digital Ocean Hugo App</a>&#xA;. I don&rsquo;t regret my decision at all, but I made a few mistakes regarding SEO that you can probably avoid if you take into account what I&rsquo;m about to tell you.&#xA;<h2 id="why-should-i-care-about-seo-if-im-a-web-developer">Why should I care about SEO if I&rsquo;m a web developer?</h2>&#xA;SEO is the factor that determines whether a website appears first in the search results of a search engine (almost always Google) or whether it is buried in the last positions, receiving little or no traffic and condemning the business it represents to bankruptcy, or if it is a personal project, to oblivion.&#xA;And I&rsquo;m not talking about subtle differences, I&rsquo;m talking about abysmal differences.&#xA;At the risk of sounding redundant, I will repeat it again: the traffic of a web site is much more important than the efficiency, the language or framework with which it is made, yes, even if you wrote it in C++ or directly in assembler.&#xA;<a href="images/aves-exoticas-org-bad-ui-good-seo.jpg" aria-label="Aves exoticas is a perfect example of a web site with good seo but awful UI">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="500" height="322" loading="lazy" src="images/aves-exoticas-org-bad-ui-good-seo.jpg" alt="Aves exoticas is a perfect example of a web site with good seo but awful UI"/>&#xA; <figcaption>Aves exoticas is the perfect example of a website visually not so attractive, but with an impeccable SEO that positions it in the first position on google.</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;<h3 id="web-developers-often-ignore-the-potential-of-seo">Web developers often ignore the potential of SEO.</h3>&#xA;Most developers have an engineering background, where efficiency, best practices and the business aspect of a website are valued and overlooked.&#xA;Hence, when a web developer launches their personal projects, they often completely ignore SEO and focus on &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/dont-obsess-about-your-web-application-performance/">optimizing their website to the maximum</a>&#xA;, usually resulting in an extremely fast, efficient, and even visually appealing website, but with no traffic.&#xA;<a href="images/web-development-assembly.webp" aria-label="Web development in assembly meme">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="500" height="654" loading="lazy" src="images/web-development-assembly.webp" alt="Web development in assembly meme"/>&#xA; <figcaption>It is said that only true programmers program in low-level languages.</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;<h2 id="my-mistakes-while-migrating-a-website-without-considering-technical-seo">My mistakes while migrating a website without considering Technical SEO</h2>&#xA;When I migrated the blog, the first thing that I blatantly ignored were the multiple consequences of doing it unanticipatedly. To begin with the sitemap, then the URL structure and finally, as the cherry on top of the cake, the absence of a schema markup.&#xA;<h3 id="the-presence-of-a-sitemap-is-crucial-in-tech-seo">The presence of a sitemap is crucial in Tech SEO</h3>&#xA;A &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/dynamic-sitemap-with-django/">sitemap is an xml file that functions as a map to navigate your site</a>&#xA;.&#xA;The sitemap that my previous website had was located in a specific address, and it changed its location when I migrated the website, so Google was unable to find it, and then what happened? Well&hellip; Google indexed the pages randomly, as you probably already know, I suffered the consequences.&#xA;One night my cell phone vibrated to the rhythm of the cascade of warnings that Google Search Console was sending in the form of notifications.&#xA;&#xA;&#xA;&#xA; &#xA; &#xA; A sitemap is an index, usually in XML format, that lists the pages of your website.&#xA;&#xA;&#xA;How could I have prevented this? By logging in my Google search console account and replacing the old sitemap address with the new one, and then asking for a new reading.&#xA;<h3 id="how-i-realized-that-url-structure-is-important-in-tech-seo">How I realized that URL structure is important in Tech SEO</h3>&#xA;But that wasn&rsquo;t all, after the migration from Wordpress to Hugo, Google detected a lot of 404 errors when accessing the old URLs and, as a punishment for being so careless, my traffic decreased by about 70%.&#xA;Why did this happen? Imagine that search engines see your website with a URL structure like the following.&#xA;<div class="mermaid">graph TD;&#xA; Website-->Year;&#xA; Year-->Month;&#xA; Month-->Day;&#xA; Day-->Entry_1;&#xA;</div>&#xA; &#xA; &#xA; And when you perform the migration, the structure changes;&#xA;<div class="mermaid">graph TD;&#xA; Website-->Posts;&#xA; Posts-->Entry_1;&#xA;</div>&#xA; &#xA; &#xA; The pages were the same but they weren&rsquo;t at the same place. I like to think that I overestimated google&rsquo;s capabilities to detect the new location of my content and act accordingly.&#xA;The important thing to remember here is that search engines do not have a way to easily recognize that one entry is exactly the same as another if it has changed location, especially if this migration involves major changes to the page. While it is true that Google can detect duplicate content and is able to render a web page, that doesn&rsquo;t mean it &ldquo;sees&rdquo; the entries visually, as a human would, in its guts it is still receiving and parsing text in the form of HTML.&#xA;How could I have prevented my traffic decline? Using a plain, old and boring redirect. It should have been enough to tell Google that if it accessed /202020/12/12/entry_1 it should redirect to /posts/entry_1, how? by returning an HTTP 302 or 308 response, Found or Permanent redirect, respectively.&#xA;<h3 id="the-absence-of-structured-data-or-schema-markup">The absence of structured data or Schema markup</h3>&#xA;When I used Wordpress the Yoast plugin took care of the structured data markup, but in Hugo this has to be done manually, so my website lasted a while without this structured data, the result? A penalty from google in the form of a decrease in the daily impressions, and therefore a traffic decline to my website.&#xA;<a href="images/schema-ld&#43;json.png" aria-label="Screenshot of structured data markup on a web site">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="677" height="196" loading="lazy" src="images/schema-ld&#43;json.png" alt="Screenshot of structured data markup on a web site"/>&#xA; <figcaption>The structured data markup for a web site looks like this</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;&#xA;&#xA;&#xA; &#xA; &#xA; Structured data markup is usually in the form of an application/ld&#43;json script on a website, it cannot be seen visually but it is read by search engines and helps them to understand the type and relationships that exist between each of the entities on your website.&#xA;&#xA;&#xA;That was the tragic story of how my traffic went down abruptly, because I was a layman in SEO.&#xA;But after that incident, I decided that i wouldn&rsquo;t allow for it to happen me again, so I started reading about SEO and I learned a lot of things that I put into practice later. I&rsquo;m not going to lie to you, right now the website is not at the level that it was before but it is heading in that direction and the best part is that I know what I&rsquo;m doing now.&#xA;I had not given myself the opportunity to touch this topic in the blog, because semantically it is quite far from what most devs understand by web development, and most devs are not really interested in SEO.&#xA;But I finally decided to write these mistakes here so they can save you a couple of headaches in the future.&#xA;

A few years ago, I migrated my website a couple of times, first from Wordpress to Frontity (A wordpress framework in React) and then from Frontity to a Digital Ocean Hugo App . I don&rsquo;t regret my decision at all, but I made a few mistakes regarding SEO that you can probably avoid if you take into account what I&rsquo;m about to tell you.&#xA;Why should I care about SEO if I&rsquo;m a web developer?

My mistakes regarding the tech SEO optimization of my website

Since ChatGPT rapidly surpassed the record of user growth, artificial intelligence is almost omnipresent in the modern metropolis collectivity. Its arrival has brought a wide gradient of expectations ranging from simple problem solving to the complete automation of our societies.&#xA;But I believe that, while AI has amazing capabilities, it is far from revolutionizing the world and achieving the full automation expected by the general public in the short term.&#xA;<a href="images/meme-ai-is-this.jpg" aria-label="Meme mocking the capabilities of AI">&#xA;&#xA; <img class="md-image" width="630" height="1061" loading="lazy" src="images/meme-ai-is-this.jpg" alt="Meme mocking the capabilities of AI"/>&#xA;&#xA;</a>&#xA;<h2 id="the-market-is-saturated-with-ai-startups">The market is saturated with AI startups</h2>&#xA;If you&rsquo;ve been <del>doom</del> scrolling on social media, you&rsquo;ll know that influencers keep talking about new AI tools that are going to revolutionize the world, <del>just like they said cryptocurrencies would,</del> from voice cloners, image and video creators, data analytics, just to name a few. There are too many AI companies! It&rsquo;s all AI!&#xA;<a href="images/ai-and-other-bubbles.jpeg" aria-label="AI and other bubbles">&#xA;&#xA; <img class="md-image" width="630" height="338" loading="lazy" src="images/ai-and-other-bubbles.jpeg" alt="AI and other bubbles"/>&#xA;&#xA;</a>&#xA;<h3 id="the-ai-company-trend">The AI company trend</h3>&#xA;In this AI fever, entrepreneurs are becoming <del>even more</del> elitist, by which I mean that all those business ideas that don&rsquo;t use AI are ipso facto discarded. &ldquo;To use AI&rdquo; has been added to the checklist of any company that wants to go to market and this, to me, is what creates this AI bubble.&#xA;<h2 id="investors-greed-and-consumers-ignorance-are-guilty-of-the-ai-bubble">Investors&rsquo; greed and consumers&rsquo; ignorance are guilty of The AI bubble</h2>&#xA;It is enough for a company to use AI to grant it with an unknown magic that makes it irresistible to the general public, and also to investors. And this because a simple reason: as a society we do not understand how AI works internally, we do not understand the statistics behind it and we endow it with the mysticism of magic.&#xA;Consumers, usually businesses, expect AI to reduce (or eliminate) the costs of hiring people and investors expect to make the investment of a lifetime.&#xA;<h2 id="ai-fever-and-capital-investment">AI fever and capital investment</h2>&#xA;As I said, investors don&rsquo;t want to be left out of this party and are so eager to hit the jackpot and become the new Zuckerberg of artificial intelligence that they open their wallets without thinking every time they hear the word &ldquo;AI&rdquo; in the same sentence as &ldquo;disruptive.&rdquo;&#xA;<a href="images/wallstreet-is-dumb.jpg" aria-label="Wallstreet has no idea about AI">&#xA;&#xA; <img class="md-image" width="630" height="391" loading="lazy" src="images/wallstreet-is-dumb.jpg" alt="Wallstreet has no idea about AI"/>&#xA;&#xA;</a>&#xA;But, in my opinion, this is all just a bunch of companies and entrepreneurs acting on the above, just as &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/devin-ai-the-supposed-replacement-for-programmers/">creators of Devin, the supposed replacement for programmers</a>&#xA;, and the creators of &#xA;&#xA;<a class="markdown-link" href="https://www.rabbit.tech/" rel="noopener nofollow" target="_blank">Rabbit R1</a>&#xA; are probably doing.&#xA;The market is trying to make a quick and easy buck from the suddenly growing interest of tech laymen in something as abstract, and with such esoteric characteristics, as AI.&#xA;<h2 id="many-of-the-ai-solutions-are-just-plain-chatgpt-wrappers">Many of the AI solutions are just plain ChatGPT wrappers</h2>&#xA;In addition to this, most people involved in the financial side of AI don&rsquo;t understand that not much has really changed in the coding world, most solutions just use ChatGPT on the backend, along with a visually appealing interface to present themselves as the next unicorn and look for easy money from investors.&#xA;<a href="images/ai-company-chatgpt.jpg" aria-label="Startups are just a wrapper for chatgpt">&#xA;&#xA; <img class="md-image" width="630" height="486" loading="lazy" src="images/ai-company-chatgpt.jpg" alt="Startups are just a wrapper for chatgpt"/>&#xA;&#xA;</a>&#xA;And not that the above is wrong, but I would prefer that all the possibilities that AI has to offer be explored, that we train neural networks to automate every tedious aspect of society and free humans from the paradigm of performing repetitive 9-5 tasks or maybe to improve human&rsquo;s health via &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/artificial-intelligence-drug-design-for-developers/">drug design</a>&#xA;. I want more investment in AI, but one that &ldquo;adds value,&rdquo; not just seeks to profit as quick as possible.&#xA;<h2 id="companies-are-running-out-of-data-to-train-llm">Companies are running out of Data to train LLM</h2>&#xA;I stumbled upon this video the other day, and I agree with this fine gentleman: Companies are running out of data, it was never about computing power, it&rsquo;s all about curated and reliable datasets to train AI.&#xA;&#xA;&#xA; &#xA; <div style="position: relative; padding-bottom: 56.25%; height: 0; overflow: hidden;">&#xA; <iframe allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" allowfullscreen="allowfullscreen" loading="eager" referrerpolicy="strict-origin-when-cross-origin" src="https://www.youtube.com/embed/nkdZRBFtqSs?autoplay=0&controls=1&end=0&loop=0&mute=0&start=0" style="position: absolute; top: 0; left: 0; width: 100%; height: 100%; border:0;" title="How Developers might stop worrying about AI taking software jobs and Learn to Profit from LLMs"&#xA; ></iframe>&#xA; </div>&#xA;&#xA;The greed that feeds the use of AI is going to flood the internet with a myriad of AI articles, that are going to be used to feed, and afterwards be regurgitated by the AI, over and over again <del>as in the human centipede movie</del>.&#xA;<h2 id="the-tragic-end-of-the-ai-bubble-and-the-new-normal">The tragic end of the AI Bubble and the New Normal</h2>&#xA;Having said the above, it seems that I believe that all this about AI is nothing more than smoke and mirrors, but that&rsquo;s far from the truth, I believe that AI is going to stay and it has potential for a social revolution but, at least in the short term, it will be exclusive to a very small group of companies, among which I highlight openAI, Google, Microsoft and the usual players.&#xA;Don&rsquo;t get me wrong, there is an AI bubble, and the bubble will burst and only those companies with the potential to change the game forever will remain. Tools like Sora, Midjourney, ChatGPT, Eleven Labs or Watson.&#xA;It is up to them to decide the pace at which this transition will take place despite what the market is trying to shove down your throat.&#xA;<a href="images/ai-bubble-explosion-meme.jpg" aria-label="dragon ball meme about the AI bubble bursting">&#xA;&#xA; <img class="md-image" width="630" height="473" loading="lazy" src="images/ai-bubble-explosion-meme.jpg" alt="dragon ball meme about the AI bubble bursting"/>&#xA;&#xA;</a>&#xA;My prediction regarding the AI bubble, is that all other companies that don&rsquo;t have their own unique neural networks or some intellectual property to protect them, are going to cannibalize and commoditize themselves, and that, when the AI bubble bursts, a lot of people are going to lose money in the process.&#xA;

Since ChatGPT rapidly surpassed the record of user growth, artificial intelligence is almost omnipresent in the modern metropolis collectivity. Its arrival has brought a wide gradient of expectations ranging from simple problem solving to the complete automation of our societies.&#xA;But I believe that, while AI has amazing capabilities, it is far from revolutionizing the world and achieving the full automation expected by the general public in the short term.

The Rise and Fall of the AI Bubble

This post is for you, who want to become independent from companies and are looking to create your own projects in the internet world. Have you ever thought if those extra milliseconds of performance that we get by switching a project to a more verbose language really matter that much or if the search for the fastest framework is really worth it?&#xA;In the world of programmers there is an obsession with speed and performance; we want to squeeze every possible millisecond out of the language and reduce memory consumption to the minimum possible and write queries in their most elegant version that pushes our database to its speed limit and and subject them to the most rigorous &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/the-big-o-notation/">Big O performance analysis</a>&#xA;.&#xA;<a href="images/rust-and-go-performance-for-common-data-structures-arrays.webp" aria-label="Rust vs go Benchmark">&#xA;&#xA; <img class="md-image" width="600" height="371" loading="lazy" src="images/rust-and-go-performance-for-common-data-structures-arrays.webp" alt="Rust vs go Benchmark"/>&#xA;&#xA;</a>&#xA;In this constant search we go from high level languages to lower level languages, we wander through the darkest corners of the documentation towards the most esoteric runtimes written in arcane languages whose names seem to be taken out of a dictionary of another language. Did any particular one come to your mind?.&#xA;Throughout this virtual odyssey, we completely forgot about what is probably the only factor that matters: the boring market.&#xA;<h2 id="how-much-do-requests-per-second-matter-at-a-startup">How much do requests per second matter at a startup?</h2>&#xA;If you, or your company, are not a major league player on the Internet, you are probably giving more importance than necessary to the fact that your application serves 1 request per second instead of 100.&#xA;<a href="images/techempower-benchmark.png" aria-label="Requests per second techempower benchmark">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="864" height="531" loading="lazy" src="images/techempower-benchmark.png" alt="Requests per second techempower benchmark"/>&#xA; <figcaption>Some frameworks can handle up to 600k requests per second</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;Yes, it is true that we are talking about a factor of 100, but consider the following:&#xA;One request per second means 60 in a minute, 3600 in an hour and 86400 a day.&#xA;Are you really worried about your application having a traffic of 86400 requests in a day? If you already have such traffic, paying an extra developer to tune the gears of your software should not be a problem, and if it is, you probably don&rsquo;t have a performance problem, but a monetization problem.&#xA;<h2 id="does-memory-consumption-matter-in-a-new-web-application">Does memory consumption matter in a new web application?</h2>&#xA;Does it matter whether your application runs with minimal memory consumption using a low-level language, or with higher consumption using a high-level language. I would say it depends; if your application or project is new, it&rsquo;s probably worth paying a few dollars more per month for extra memory in exchange for a higher development speed in each iteration.&#xA;I&rsquo;m not saying that it&rsquo;s wrong to take care of the technical aspects, but right now there are more important things, such as acquiring information that will translate into profitability later, or allocating more resources to marketing and advertising your startup or project than wasting time ironing out the kinks in your code.&#xA;Optimizing for good SEO is also more important than the memory consumption or the efficiency of your application, believe me, &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/my-mistakes-regarding-the-tech-seo-optimization-of-my-website/">I learned the importance of SEO from my own mistakes</a>&#xA;&#xA;I&rsquo;ll say it again just in case you didn&rsquo;t get it: marketing and sales are more important than the quality of your software when you start a project.&#xA;<a href="images/wordpress-meme.jpg" aria-label="Wordpress vs node meme">&#xA;&#xA; <img class="md-image" width="800" height="720" loading="lazy" src="images/wordpress-meme.jpg" alt="Wordpress vs node meme"/>&#xA;&#xA;</a>&#xA;<h2 id="development-speed-vs-performance">Development speed vs. performance</h2>&#xA;For most startups or solopreneurs, the market exploration process will be more important than reducing resource consumption. What good does it do you to cut your RAM and processor consumption in half if your iterations are going to go from one week to two and a half weeks?&#xA;<a href="images/rustaceans-vs-gophers.png" aria-label="Time compilation differences between rust and go meme">&#xA;&#xA; <img class="md-image" width="800" height="612" loading="lazy" src="images/rustaceans-vs-gophers.png" alt="Time compilation differences between rust and go meme"/>&#xA;&#xA;</a>&#xA;<h3 id="usually-fast-enough-is-enough">Usually fast enough is enough</h3>&#xA;Do not choose an efficient language, but one that allows you to be flexible to changes and adapt quickly while obtaining information. In this case, the speed of developing new features or modifying existing ones is much more important than their performance.&#xA;Remember that in technology everything is a trade-off, in this case performance for productivity.&#xA;Also, keep in mind that this also applies when choosing the tools you know; you may be faster programming in a low level language that you already master, than in a high level language that you don&rsquo;t master.&#xA;<h3 id="keep-the-technical-debt-in-mind">Keep the technical debt in mind</h3>&#xA;Another thing, when optimizing for development speed, don&rsquo;t forget to consider technical debt, find the tipping point and pivot towards scalability.&#xA;<a href="images/design-stamina-graph.jpg" aria-label="Design stamina graph">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="618" height="329" loading="lazy" src="images/design-stamina-graph.jpg" alt="Design stamina graph"/>&#xA; <figcaption>Credits: Martin Fowler</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;<h2 id="situations-where-performance-and-security-do-matter">Situations where performance and security do matter.</h2>&#xA;Does it mean that you should forget about all other languages and try to implement all your ideas in a tool written in a mediocre language <del>javascript</del> just for the speed of development?, no, I think there are situations where it is crucial to choose the fastest, safest and most efficient, like for example: for browsers, game engines or operating systems (however this post is about web applications), although, again, you are not going to design an operating system by yourself&hellip; unless you want your OS to be the third temple of Jerusalem and you want to communicate with god.&#xA;<a href="images/temple-os.webp" aria-label="Meme of temple os, a system that supposedly would be the third temple of Jerusalem and would allow to communicate with god.">&#xA;&#xA; <img class="md-image" width="800" height="881" loading="lazy" src="images/temple-os.webp" alt="Meme of temple os, a system that supposedly would be the third temple of Jerusalem and would allow to communicate with god."/>&#xA;&#xA;</a>&#xA;Using a low-level language is usually the right decision for situations where performance is critical, you don&rsquo;t want services where people&rsquo;s lives or health are at stake written in high-level languages, which tend to be more flexible in typing and more prone to runtime errors.&#xA;You will also want performance and security in environments where you deal with things even more important than people&rsquo;s lives, such as applications related to the financial market and where significant amounts of money are handled (sarcasm, just in case, the only people who think like that are the people on Wall street).&#xA;<a href="images/gamestop-meme.jpg" aria-label="Gamestop meme about an angry millonaire upsed about reddit strategy">&#xA;&#xA; <img class="md-image" width="720" height="899" loading="lazy" src="images/gamestop-meme.jpg" alt="Gamestop meme about an angry millonaire upsed about reddit strategy"/>&#xA;&#xA;</a>&#xA;<h2 id="top-tools-to-get-shit-done-in-web-development">Top Tools To Get Shit Done in web development</h2>&#xA;I am an advocate of avoiding reinventing the wheel every time. It&rsquo;s quite annoying to have to create authentication systems, CRUDS, database queries over and over again, even though some communities, like Go, prefer to implement everything from scratch.&#xA;Here is a list of some of my favorite solutions to save you all the boilerplate and focus on what&rsquo;s important, that although they don&rsquo;t have the best performance, they focus on having working prototypes as soon as possible.&#xA;<ul>&#xA;<li>Wordpress: &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/to-program-a-blog-or-to-use-wordpress/">because you already know&rsquo;</a>&#xA;</li>&#xA;<li>Ruby on Rails: Mature framework, with a long history and easy to use.</li>&#xA;<li>AdonisJs: Javascript with ORM and authentication included.</li>&#xA;<li>Django: &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/why-should-you-use-django-framework/">It&rsquo;s easy to develop a MVP without having to reinvent the wheel</a>&#xA;, also there is lot of info out there on &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/how-to-scale-a-django-app-to-serve-one-million-users/">how to scale it to serve up to one million users.</a>&#xA;</li>&#xA;<li>Pocketbase: &#xA;&#xA;<a class="markdown-link" href="https://pocketbase.io/" rel="noopener" target="_blank">Portable backend made in Go, a single binary, authentication and CRUD</a>&#xA;</li>&#xA;<li>Supabase: Another portable backend, but in JavaScript</li>&#xA;<li>Appwrite: &#xA;&#xA;<a class="markdown-link" href="https://appwrite.io/" rel="noopener" target="_blank">Authentication, Databases, Functions, Storage, and Messaging</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/cookiecutter-django-for-configuring-and-deploying-in-django/">Cookiecutter: templates to save you Boilerplate, the Django one is very good</a>&#xA;</li>&#xA;<li>Hugo: Static site generator, fast enough (though not as fast as its Rust version, Zola)</li>&#xA;<li>No-code tools</li>&#xA;<li>Daisy UI: CSS library based on Tailwind.</li>&#xA;</ul>&#xA;<h2 id="care-for-performance-only-when-it-matters">Care for performance only when it matters</h2>&#xA;Once the cash flow is sufficient, rewrite your application in a low-level language, get rid of the ORM and run your SQL queries manually, implement your own abstractions instead of using a framework, refactor your entire app with a more robust architecture pattern, and hire specialists to take care of every extra millisecond in your systems.&#xA;When that time comes, I hope you get to the point where &#xA;&#xA;<a class="markdown-link" href="https://discord.com/blog/why-discord-is-switching-from-go-to-rust" rel="noopener" target="_blank">switching from a language like Go to Rust, as happened to Discord</a>&#xA;, really makes a difference.&#xA;

This post is for you, who want to become independent from companies and are looking to create your own projects in the internet world. Have you ever thought if those extra milliseconds of performance that we get by switching a project to a more verbose language really matter that much or if the search for the fastest framework is really worth it?&#xA;In the world of programmers there is an obsession with speed and performance; we want to squeeze every possible millisecond out of the language and reduce memory consumption to the minimum possible and write queries in their most elegant version that pushes our database to its speed limit and and subject them to the most rigorous Big O performance analysis .

Don't Obsess About Your Web Application Performance

Working with Javascript is frustrating and, sometimes, combining it with HTML can be desperate due to its lack of internal coherence. On top of that, using it to handle dates, which requires considering the handling of timezones, different ways to represent them and the required sensitivity: seconds, minutes, milliseconds, etc. makes it a torture.&#xA;<h2 id="javascript-handles-dates-in-a-strange-way">Javascript handles dates in a strange way</h2>&#xA;Javascript uses months starting from index 0 and days from index 1, two objects with the same date are unequal when compared with === (yes, I know that what is compared are the objects and not the dates), but it is just the fact that it is not intuitive, the language user is not interested in the objects in memory itself, but what they represent. Languages like &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/python-vs-javascript-which-is-the-best-programming-language/">Python has better abstractions than those handled by Javascript</a>&#xA;&#xA;<a href="images/date-javascript.webp" aria-label="Javascript&amp;rsquo;s date management is not intuitive">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="908" height="522" loading="lazy" src="images/date-javascript.webp" alt="Javascript&amp;rsquo;s date management is not intuitive"/>&#xA; <figcaption>Javascript&#39;s date management is not intuitive</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;<h2 id="the-disconnection-between-html-and-js">The disconnection between HTML and JS</h2>&#xA;In the case of scheduling an event with a date and time, it is tempting to use the native datetime-local input already provided by HTML. However, this field by default requires a date in &ldquo;YYYYY-MM-DDThh:mm&rdquo; format, while javascript returns the dates in a Date object, which you must transform to ISO 6801 &ldquo;YYYYY-MM-DDThh:mm.iiiZ&rdquo;, where the &ldquo;i&rdquo; is microseconds (or to another format with a function of its own).&#xA;<a href="images/two-dates-javascript.png" aria-label="Two object with the same date in Javascript aren&amp;rsquo;t equal">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="479" height="195" loading="lazy" src="images/two-dates-javascript.png" alt="Two object with the same date in Javascript aren&amp;rsquo;t equal"/>&#xA; <figcaption>Javascript&#39;s abstraction when it comes to dates can be confusing</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;To perform this transformation, the most obvious way is to remove the letter &ldquo;Z&rdquo;, but if you try to assign that date to the datetime-input input, it will allow the user to select the milliseconds, which really has little application for most users. The correct thing to do would be to slice from the beginning, making a slice from position 0 to the sensitivity we need.&#xA;Well, after this the datetime-local input will work and show the date, the problem now is that after validating your HTML field and probably before saving those dates in some storage media (postgres, redis, etc.), you will want to make modifications, so you will have to convert them back to a Date object in javascript in case you want to manage them, which again implies another conversion.&#xA;<a href="images/formatting-dates-in-javascript.jpg" aria-label="A meme that with irony, makes fun of Javasript&amp;rsquo;s date management">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="740" height="357" loading="lazy" src="images/formatting-dates-in-javascript.jpg" alt="A meme that with irony, makes fun of Javasript&amp;rsquo;s date management"/>&#xA; <figcaption>Oh, mom! Not javascript again!</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;But what if we use a library to handle those changes?&#xA;<h2 id="the-js-libraries-for-time-handling-dont-solve-anything">The js libraries for time handling don&rsquo;t solve anything.</h2>&#xA;I have nothing against using Moment or react-datetimepicker, Dayjs, etc. In fact I think their developers perform a very worthy task: simplifying Javascript&rsquo;s poor date handling (if any contributor reads this, thanks).&#xA;Those libraries exist, because Javascript did a lousy job in designing its standard library. Libraries are convenient to use but, in an ideal world, they should not exist.&#xA;It may seem insignificant to you to add one more library, but it&rsquo;s not the weight that&rsquo;s the problem, it&rsquo;s the fact that a library for something as common as date handling is so necessary, plus it adds unnecessary weight to your bundle and an extra dependency to manage.&#xA;The fact that these libraries are popular only highlights the shortcomings of JavaScript as a language.&#xA;And yes, I know what you&rsquo;re thinking. Although I really like &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-programming-language-introduction-to-variables-and-data-types/">the Go programming language</a>&#xA;, I&rsquo;m also able to recognize their shortcomings and areas for improvement.&#xA;<a href="images/date_formatting_golang.webp" aria-label="Go date formatting is awful too">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="766" height="856" loading="lazy" src="images/date_formatting_golang.webp" alt="Go date formatting is awful too"/>&#xA; <figcaption>Go&#39;s date formatting, like Javascript&#39;s, is awful</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;<h2 id="algunas-librerias-para-manejar-fechas-en-javascript">Algunas librerías para manejar fechas en Javascript</h2>&#xA;¿Qué usar para manejar la fecha con Javascript? Prueba con estas librerías para manejar fechas&#xA;<ul>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://tempo.formkit.com/" rel="noopener nofollow" target="_blank">Tempo</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://momentjs.com/" rel="noopener nofollow" target="_blank">Momentjs</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://day.js.org/" rel="noopener nofollow" target="_blank">Dayjs</a>&#xA;</li>&#xA;</ul>&#xA;

Working with Javascript is frustrating and, sometimes, combining it with HTML can be desperate due to its lack of internal coherence. On top of that, using it to handle dates, which requires considering the handling of timezones, different ways to represent them and the required sensitivity: seconds, minutes, milliseconds, etc. makes it a torture.&#xA;Javascript handles dates in a strange way Javascript uses months starting from index 0 and days from index 1, two objects with the same date are unequal when compared with === (yes, I know that what is compared are the objects and not the dates), but it is just the fact that it is not intuitive, the language user is not interested in the objects in memory itself, but what they represent.

Why I abhor datetime-local and dates in Javascript?

Today this unholy news became popular, that an &ldquo;AI Software Engineer&rdquo; with the name Devin, made by &#xA;&#xA;<a class="markdown-link" href="https://www.cognition-labs.com/" rel="noopener" target="_blank">Cognition Labs</a>&#xA;, will be available on the market. And, of course, it provoked a strong reaction among the software professional community. Reactions ranging from cynicism to fear to disappointment abound in the comments on the related videos.&#xA;While we are still far from having a &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/chat-gpt-searles-chinese-room-and-consciousness/">self-aware AI</a>&#xA;, what we do have is a product with promising features that threaten to turn the technology industry upside down.&#xA;Like what features? &#xA;&#xA;<a class="markdown-link" href="https://www.cognition-labs.com/blog" rel="noopener" target="_blank">According to its creators, Devin AI can</a>&#xA;:&#xA;<ul>&#xA;<li>Use unfamiliar technologies</li>&#xA;<li>Create and deploy applications</li>&#xA;<li>Automatically find bugs</li>&#xA;<li>Train your own AI models</li>&#xA;<li>Contribute to mature repositories</li>&#xA;<li>Solve real projects on Upwork (much more than &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/i-test-chatgpt-with-codewars-coding-challenges/">solve interview code problems</a>&#xA;)</li>&#xA;</ul>&#xA;<a href="images/so-its-time-to-panic-simpsons.webp" aria-label="Simpsons meme asking if it&amp;rsquo;s time to Panic">&#xA;&#xA; <img class="md-image" width="700" height="556" loading="lazy" src="images/so-its-time-to-panic-simpsons.webp" alt="Simpsons meme asking if it&amp;rsquo;s time to Panic"/>&#xA;&#xA;</a>&#xA;<h2 id="who-is-behind-devin-ai">Who is behind Devin AI?</h2>&#xA;Behind Devin AI is Cognition labs, a relatively new company that had been kept behind the scenes until yesterday. Their &#xA;&#xA;<a class="markdown-link" href="https://twitter.com/cognition_labs" rel="noopener" target="_blank">Twitter account</a>&#xA; is less than two days old at the time of writing (although it already accumulates over 86k followers).&#xA;<h3 id="who-are-the-members-of-cognition-labs">Who are the members of Cognition labs?</h3>&#xA;There are about 10 members, between them totaling more than 10 gold medals at the International Computer Olympiad and whose members seem to have been involved in AI-related projects at companies like Google, DeepMind and Scale AI. So one can speak of a group with some level of experience.&#xA;<a href="images/meme-creador-de-devin-linuxero.jpg" aria-label="Fictitious and caricatured representation of Devin AI&amp;rsquo;s creators">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="700" height="394" loading="lazy" src="images/meme-creador-de-devin-linuxero.jpg" alt="Fictitious and caricatured representation of Devin AI&amp;rsquo;s creators"/>&#xA; <figcaption>Fictitious and caricatured representation of Devin AI&#39;s creators</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;<h3 id="who-is-funding-the-project">Who is funding the project?</h3>&#xA;So far Cognitive Labs claims to have raised about 21 MDD in a round led by Founders Fund, most notably investor Peter Thiel, former head of Paypal.&#xA;<a href="images/peter-thiel-relationships.jpeg" aria-label="Peter Thiel&amp;rsquo;s relationship diagram">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="700" height="562" loading="lazy" src="images/peter-thiel-relationships.jpeg" alt="Peter Thiel&amp;rsquo;s relationship diagram"/>&#xA; <figcaption>Source: https://knowyourmeme.com/photos/2402121-peter-thiel</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;<h2 id="whats-going-to-happen-to-the-programmers---are-they-at-risk">What&rsquo;s going to happen to the programmers - are they at risk?</h2>&#xA;Well, it is difficult to know for sure, given the lack of information. However, I propose a couple of likely scenarios:&#xA;<ul>&#xA;<li>Devin AI will replace the programmers and revolutionize the industry.</li>&#xA;<li>Devin AI will not rise to the occasion and will fall into oblivion.</li>&#xA;</ul>&#xA;<h3 id="devin-ai-will-replace-the-programmers-and-take-their-jobs">Devin AI will replace the programmers and take their jobs.</h3>&#xA;Who do you think would win in a battle to produce more books, 1000 ancient Egyptian scribes or a photocopier hooked up to a computer?&#xA;I am of the opinion that the second option, simply the capabilities of the printer to produce pages faster, with fewer errors and in a fraction of the time, are beyond the capabilities of the scribes. While it is true that a person is required to set up and use the printer, that does not imply that scribes stand a chance. Similarly, while programmers will still be required and more jobs will be &ldquo;created&rdquo; as is usually claimed, the real question is: how many jobs will be lost for every new job that is created?.&#xA;<a href="images/Devin-AI-vs-you.jpg" aria-label="Image of a boot crushing a human face">&#xA;&#xA; <img class="md-image" width="700" height="394" loading="lazy" src="images/Devin-AI-vs-you.jpg" alt="Image of a boot crushing a human face"/>&#xA;&#xA;</a>&#xA;Let&rsquo;s continue with this thought experiment, let&rsquo;s assume, for a moment, that Devin AI does exactly what he says. Since Devin AI is a tool, it still requires input from a human being to function, so the &ldquo;output&rdquo;, i.e. its performance, will depend on how good its &ldquo;input&rdquo;, i.e. the person giving it the instructions, is.&#xA;<a href="images/prompt-engineer.png" aria-label="Winnie the Pohh meme">&#xA;&#xA; <img class="md-image" width="700" height="509" loading="lazy" src="images/prompt-engineer.png" alt="Winnie the Pohh meme"/>&#xA;&#xA;</a>&#xA;This means that the profession of prompt engineer will become a reality, and with the consequence that those people with superior abstraction, writing and lexical abilities will become practically gods of this new utopia (or dystopia, depending on how you see it).&#xA;In addition, all those professions in charge of perfecting AI models will become professions with a very high demand, since any company that wants to compete and stay afloat will need one.&#xA;<h4 id="new-opportunities-after-the-end-of-programming">New opportunities after the end of programming</h4>&#xA;Getting a job if you are new in the industry will be quite complicated, but at the same time the barrier to create digital businesses will decrease and it will be more important to identify and solve problems. Becoming a solopreneur or freelancer will be incredibly easy, as the technical skills required will be significantly reduced and you may be better off aiming in that direction.&#xA;How likely do I see this scenario? The truth is that I consider it a pretty unlikely scenario.&#xA;<h3 id="devin-ai-is-just-temporary-hype-and-will-be-forgotten-soon">Devin AI is just temporary hype and will be forgotten soon.</h3>&#xA;The second possibility is that nothing happens. Yes, nothing.&#xA;It has happened multiple times in the past; every great forgotten idea starts with the promise of revolutionizing the world, as it happened with no-code or Dreamweaver (A WYSIWYG editor to create websites from 2007). Both were technologies that from one moment to the next threatened to change the world of technology forever, and failed to do so.&#xA;Remember &#xA;&#xA;<a class="markdown-link" href="https://github.com/daveshap/OpenAI_Agent_Swarm" rel="noopener" target="_blank">Agent Swarm AI</a>&#xA;? It also generated a lot of expectations but in the end it didn&rsquo;t crystallize into anything.&#xA;So far Copilot, ChatGPT and probably Devin AI have been nothing more than &ldquo;google searches&rdquo; on steroids, they can give you the information you request directly, but it&rsquo;s not necessarily real and fail-safe. The iterative process offered by this system improves quite a bit on the usual question-answer dynamic, but it is still immune to falling into loops due to problems it can&rsquo;t solve or producing something totally different from what you ask for, for now we need to test it a lot more.&#xA;In addition to the above, there is another aspect that we are missing.&#xA;<h4 id="the-financial-aspect-of-artificial-intelligence">The financial aspect of Artificial Intelligence.</h4>&#xA;Let me describe a situation:&#xA;<ol>&#xA;<li>A group of entrepreneurs come up with a novel product.</li>&#xA;<li>It goes viral and everyone talks about how it will forever change our everyday life.</li>&#xA;<li>The creators receive seed capital from many, many investors.</li>&#xA;<li>It ends up becoming just another tool and everything stays the same.</li>&#xA;</ol>&#xA;Does it sound like anything like that? Maybe they are just a group of people looking to become millionaires and we&rsquo;re in the middle of an &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/the-rise-and-fall-of-the-ai-bubble/">AI bubble</a>&#xA;.&#xA;<a href="images/its-all-about-shareholders.jpg" aria-label="Meme of omniman talking to his son about shareholders&amp;quot;">&#xA;&#xA; <img class="md-image" width="700" height="653" loading="lazy" src="images/its-all-about-shareholders.jpg" alt="Meme of omniman talking to his son about shareholders&amp;quot;"/>&#xA;&#xA;</a>&#xA;Consider that, in the world of money, appearances play a major role. Right now, only a few people who have had access to Devin AI are raving about the tool. Sounds too good, doesn&rsquo;t it? This could all be a marketing campaign to inflate expectations, attract investors and make &ldquo;easy&rdquo; money.&#xA;But didn&rsquo;t Peter Thiel just invest money? Yes, but that doesn&rsquo;t mean anything. If you are an investor, you don&rsquo;t care if the project exists for a month, two months, a decade or two, the only important thing is that it is profitable enough for you according to your own investment criteria. In other words: What does it matter if the project dies if I can turn 21 MDD into 40 MDD in less than a year?&#xA;<a href="images/meme-rapper-devin-access.jpg" aria-label="Meme of the rapper rejecting the first option applied to Cognition labs">&#xA;&#xA; <img class="md-image" width="700" height="604" loading="lazy" src="images/meme-rapper-devin-access.jpg" alt="Meme of the rapper rejecting the first option applied to Cognition labs"/>&#xA;&#xA;</a>&#xA;It strikes me that the way to request access to Devin AI is through a google form instead of using an App developed with the same model, which would be the perfect cover letter for this technology. After all, it&rsquo;s not like it&rsquo;s outside the capabilities of their model, it&rsquo;s not an application with 1000 microservices, load balancing, streaming and a recommendation engine, it&rsquo;s a plain simple and common registration form.&#xA;I consider this scenario more likely, but let&rsquo;s wait a year or two and see together if Devin AI lives up to its promise. My bet is that Devin won&rsquo;t replace programmers.&#xA;

Today this unholy news became popular, that an &ldquo;AI Software Engineer&rdquo; with the name Devin, made by Cognition Labs , will be available on the market. And, of course, it provoked a strong reaction among the software professional community. Reactions ranging from cynicism to fear to disappointment abound in the comments on the related videos.&#xA;While we are still far from having a self-aware AI , what we do have is a product with promising features that threaten to turn the technology industry upside down.

Devin AI Will this AI Replace Programmers?

It is no secret that these days software, in general, is trending towards a SAAS business model. However if you were there when the holy scriptures of the internet were written, you will know that this trend is rather recent.&#xA;<h2 id="ots-and-software-as-a-physical-product">OTS and software as a physical product</h2>&#xA;When the internet first came into use, it was common practice to sell software as if it were a regular supermarket product; you made a one-time payment and the product was yours, you owned it outright and you were free to use it until the inevitable collapse of our modern society.&#xA;Not only that, but you physically owned it outside of computers; either in the form of CDs, floppy disks and later DVDs.&#xA;But was this situation a corporate decision? Well, yes and no, let me expand on this point a bit.&#xA;<h3 id="the-lack-of-payment-methods-and-the-slow-internet-of-yesteryear">The lack of payment methods and the slow internet of yesteryear</h3>&#xA;Much of the commercial software was too heavy, in proportion to the size of the storage devices, to download without problems.&#xA;In the old days, internet connections were incredibly slow and unstable, leaving aside the strange noise that preceded every connection, old internet pirates know what I&rsquo;m talking about.&#xA;<a href="images/slow-internet-connection.jpg" aria-label="Windows downloading that states years of waiting time">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="650" height="360" loading="lazy" src="images/slow-internet-connection.jpg" alt="Windows downloading that states years of waiting time"/>&#xA; <figcaption>Windows downloading that states years of waiting time</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;As a result, many companies chose to distribute their software via CDs or other external media.&#xA;<a href="images/photoshop-code-box-and-disk.jpg" aria-label="Old Adobe Photoshop installation Floppy disks">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="789" height="369" loading="lazy" src="images/photoshop-code-box-and-disk.jpg" alt="Old Adobe Photoshop installation Floppy disks"/>&#xA; <figcaption>Old Adobe Photoshop installation Floppy disks</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;<h3 id="making-payments-over-the-internet-was-not-something-common">Making payments over the internet was not something common.</h3>&#xA;Making payments over the internet was unusual, paypal didn&rsquo;t exist and there were no other companies offering the service, plus people were wary of the world of online transactions. I don&rsquo;t blame them, HTTPS didn&rsquo;t exist, let alone strong cryptographic standards to protect your personal data.&#xA;<h2 id="the-advent-of-saas-the-recurring-payment-model-and-saas-hell">The advent of SAAS, the recurring payment model and SAAS hell</h2>&#xA;The landscape changed and the internet evolved, or maybe it&rsquo;s better to say it became corporatized.&#xA;Companies like Adobe grew and realized that they could save a lot of money by eliminating the logistics of distributing physical products and focusing solely on offering their content over the web.&#xA;Subsequently, they found that it was more lucrative to rent the software, probably because:&#xA;<ul>&#xA;<li>They dampened the variability of sales. They no longer had to worry about sudden changes in sales.</li>&#xA;<li>They guaranteed a steady cash flow that allowed them to better plan their costs given the stability.</li>&#xA;<li>The user was unable to use older versions of the software at zero cost.</li>&#xA;</ul>&#xA;Offering SAAS allowed companies to make a product or service available to the market with a rentier business model and ensure that if customers wanted to continue using a product (or service) they would have to pay month to month or forget about using it.&#xA;<a href="images/adobe-meme-saas.jpg" aria-label="Meme about Adobe and its obsession for profit">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="552" height="582" loading="lazy" src="images/adobe-meme-saas.jpg" alt="Meme about Adobe and its obsession for profit"/>&#xA; <figcaption>Meme about Adobe and its obsession for profit</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;This affected mainly those people who rarely updated their software. If they wanted to use it the following month, they now had to pay.&#xA;<a href="images/not-stonks.jpg" aria-label="Meme about the modification of the world stocks into stonks">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="600" height="338" loading="lazy" src="images/not-stonks.jpg" alt="Meme about the modification of the world stocks into stonks"/>&#xA; <figcaption>Stonks</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;At the same time, however, it allowed companies to release new versions of their software more frequently and to iterate more quickly on user feedback to improve their product, allowing them to improve their product and make it more attractive to customers.&#xA;That said, you might think that migrating to a SAAS model would make companies millionaires, but it didn&rsquo;t, at least not for Adobe.&#xA;<a href="images/adobe-stocks.png" aria-label="Adobe made obligatory monthly payments in 2017">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="741" height="610" loading="lazy" src="images/adobe-stocks.png" alt="Adobe made obligatory monthly payments in 2017"/>&#xA; <figcaption>Adobe made obligatory monthly payments in 2017</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;Although it is worth noting that if gross profits did not increase dramatically, his SAAS business allowed him to operate with a gross margin of 93%. Imagine, 93%, Jeff Bezos&rsquo; wettest dream!&#xA;<a href="images/adobe-revenue-pricing-2014.webp" aria-label="Source: https://tomtunguz.com/adobe-saas-growth">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="1280" height="960" loading="lazy" src="images/adobe-revenue-pricing-2014.webp" alt="Source: https://tomtunguz.com/adobe-saas-growth"/>&#xA; <figcaption>Source: https://tomtunguz.com/adobe-saas-growth</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;Was it a smart move? Well at least it seems so, since they have kept it up all these years, many, many companies followed the trend along with Adobe and adopted SAAS models.&#xA;<h3 id="saas-hell">SAAS Hell</h3>&#xA;As more companies adopted SAAS, we went from living in a world of CDs, DVDs and floppy disks to one with a long list of monthly payments for the software we use: netflix, slack, chatGPT, buffer, nuelink, X, Adobe, etc. Offering the companies some pretty convenient recurring revenue and us a list of bills to pay each month.&#xA;<h2 id="eleven-and-the-return-of-ots">Eleven and the return of OTS</h2>&#xA;And right in the middle of this sea of SAAS, Once appears as an island that offers refuge from the onslaught of companies that want to keep you subscribed for as long as possible.&#xA;Eleven is a company that plans to go against the current SAAS trend. Eleven claims that it is unfair that customers have to pay so much money without ever owning the product, similar to the landlord-tenant model, where the landlord will not own the real estate, even if he has paid more money than the real estate to the landlord.&#xA;In his manifesto, Eleven, with the eloquence of the best politician, promises one-time payment for his software and access to the code, waving the flag of a promising post-SAAS era.&#xA;<a href="images/once-manifesto.png" aria-label="Once Manifesto">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="1148" height="660" loading="lazy" src="images/once-manifesto.png" alt="Once Manifesto"/>&#xA; <figcaption>Once Manifesto</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;Surprisingly, their promise is not based on empty words; they have developed an application similar to Slack, called campfire, which promises to reduce operating costs by up to 99.9% and was quite well received at X.&#xA;<blockquote class="twitter-tweet">&quot;Just look at that 3-year TOC. Campfire running on Hetzner would cost you $479 for 500 users over three years ($299 + 36 * $5). Slack with the same number of seats would cost you $270,000!!! The ONCE solution is literally 99.9% cheaper. It’s crazy.&quot; <a href="https://t.co/4eZHS5Xz6s">https://t.co/4eZHS5Xz6s</a>&mdash; DHH (@dhh) <a href="https://twitter.com/dhh/status/1753131755346047307?ref_src=twsrc%5Etfw">February 1, 2024</a></blockquote>&#xA;<script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script>&#xA;&#xA;&#xA;<h2 id="some-ots-and-saas-considerations">Some OTS and SAAS considerations.</h2>&#xA;What advantages do I see? Well the most obvious one, money, paying $299 USD is much better than paying a recurring subscription of $7.25/user/month for decades. The price is incredibly cheap for a company (although a bit more significant for an individual, so I&rsquo;ll be looking forward to trying it out). Add to this the obvious advantage of total control over the data, as the database will be completely in the clients&rsquo; possession and, surprisingly, access to the code, allowing them to extend it and integrate it with other systems (license permitting).&#xA;The disadvantages? You have to be sure that campfire will not disappear leaving you with a deprecated, unsupported product. Not to mention the increased responsibility, as you will now be responsible for keeping the application running, either directly or by hiring someone else, which depending on the number of users and workload may or may not be cost effective.&#xA;From Eleven&rsquo;s point of view, I would point out that it is disadvantageous to provide the source code to your customers, because you expose yourself to the development of competing products, but I&rsquo;m not saying it, some of them will be able to develop the application for you.&#xA;<h2 id="references">References:</h2>&#xA;<ul>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://www.linkedin.com/pulse/why-adobe-shifted-subscription-model-travis-hardman" rel="noopener" target="_blank">Why Adobe Shifted to a Subscription Model</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://once.com/" rel="noopener" target="_blank">Once Manifest</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://tomtunguz.com/adobe-saas-growth" rel="noopener" target="_blank">Adobe SAAS Growth</a>&#xA;</li>&#xA;</ul>&#xA;

It is no secret that these days software, in general, is trending towards a SAAS business model. However if you were there when the holy scriptures of the internet were written, you will know that this trend is rather recent.&#xA;OTS and software as a physical product When the internet first came into use, it was common practice to sell software as if it were a regular supermarket product; you made a one-time payment and the product was yours, you owned it outright and you were free to use it until the inevitable collapse of our modern society.

SAAS and OTS as business models and my opinion on Once

The uses of artificial intelligence go beyond &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/i-test-chatgpt-with-codewars-coding-challenges/">solving coding problems</a>&#xA;, and regardless of whether this &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/chat-gpt-searles-chinese-room-and-consciousness/">artificial intelligence is conscious or not</a>&#xA;, it has endless applications. One of the most interesting applications for artificial intelligence is the development of new drugs. Bringing a new drug to market is an arduous, costly and, in most cases, unsuccessful process. Artificial intelligence can speed up the process enormously and narrow down the new drug candidates to a few, rather than dozens of them.&#xA;For this post I&rsquo;m going to take some liberties and simplify concepts and sacrifice some (or a lot) of precision for the sake of better understanding. If you have doubts about who I am to talk about these topics, and about my credentials, feel free to ask me on social networks.&#xA;First I&rsquo;m going to briefly explain the basics of how a drug works.&#xA;<h2 id="how-does-a-drug-work-in-humans-explained-for-developers">How does a drug work in humans explained for developers?</h2>&#xA;When you ingest a drug orally, it enters your digestive system, is absorbed by it and transported into your blood. Once in the blood, the circulatory system is responsible for distributing it throughout the body. The blood has contact with all your cells. When the drug reaches the right cells, it binds to cell receptors, which trigger a normal cell function; either releasing insulin into the body, or blocking the secretion of a hormone.&#xA;<a href="images/Receptor_%28Biochemistry%29.svg.png" aria-label="Representation of a cell receptor. The blue and yellow part represents the membrane of a cell. By Wyatt Pyzynski - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=69535544.">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="1920" height="1153" loading="lazy" src="images/Receptor_%28Biochemistry%29.svg.png" alt="Representation of a cell receptor. The blue and yellow part represents the membrane of a cell. By Wyatt Pyzynski - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=69535544."/>&#xA; <figcaption>Representation of a cell receptor. The blue and yellow part represents the membrane of a cell. By Wyatt Pyzynski - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=69535544.</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;At the code level, you can think of a drug as a function that calls another function that already exists in the human body:&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-javascript" data-lang="javascript">function releaseInsulin(){}&#xA;&#xA;function administerDrug(drug){&#xA; // ...&#xA; releaseInsulin()&#xA;}&#xA;</code></pre></div><h3 id="how-does-the-drug-know-which-cells-to-act-on">How does the drug know which cells to act on?</h3>&#xA;The relationship between a drug and a cell receptor follows a key-lock mechanism, where the drug (the key) will only activate the functions of those cells that have a receptor (the lock) that &ldquo;fits&rdquo; with the drug.&#xA;Whether they fit or not depends on the three-dimensional structure of the molecule and the receptor.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-javascript" data-lang="javascript">function releaseInsulin(){}&#xA;&#xA;function administerDrug(drug){&#xA; if(isReceptorCompatible(cell, drug)){&#xA; releaseInsulin()&#xA; }&#xA;}&#xA;</code></pre></div>And not only that, a drug may partially fit a receptor, which may cause an effect with less intensity than if it did fit perfectly, and furthermore, not fitting perfectly could make it activate other receptors that would trigger unwanted side effects.&#xA;<a href="images/paracetamol_key_lock.png" aria-label="Look how the molecule fits perfectly into this receptor.">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="960" height="927" loading="lazy" src="images/paracetamol_key_lock.png" alt="Look how the molecule fits perfectly into this receptor."/>&#xA; <figcaption>Look how the molecule fits perfectly into this receptor.</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;<h3 id="drugs-have-undesirable-side-effects">Drugs have undesirable side effects.</h3>&#xA;Administering a drug is not as simple as an &ldquo;A&rdquo; produces &ldquo;B&rdquo;. A drug does not usually have only one effect, but multiple ones. There are even drugs that have as a side effect the possibility of sudden death, yes, just as you are reading it, you take it and there is a possibility (tiny, yes) that you will drop dead.&#xA;An optimal drug will cause the desired effect with a minimum of side effects, both in the short and long term.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-javascript" data-lang="javascript">function releaseInsulin(){}&#xA;&#xA;function applyDrug(drug){&#xA; if(isReceptorCompatible(cell, drug)){&#xA; // desired effects&#xA; releaseInsulin()&#xA; // undesired effects&#xA; increaseDizzyness()&#xA; createRash()&#xA; }&#xA;}&#xA;</code></pre></div><h3 id="how-long-does-a-drug-last-in-the-body">How long does a drug last in the body?</h3>&#xA;Well, the answer to that is &ldquo;it depends&rdquo;. It depends on each drug, some may last for minutes, some may last for hours and of others we may find traces even weeks or months later. But, generally they all follow the same pattern, the same phases and always in this same order:&#xA;<ul>&#xA;<li>Absorption: if the route of administration is intravenous it is instantaneous.</li>&#xA;<li>Distribution: The blood is responsible for carrying it throughout the body and its physicochemical properties determine where it remains.</li>&#xA;<li>Metabolism: Generally, the liver begins to break down the drug and thus its effect ends.</li>&#xA;<li>Excretion: Mostly excreted through the kidneys, in the urine.</li>&#xA;</ul>&#xA;<a href="images/farmacocinetics.jpg" aria-label="">&#xA;&#xA; <img class="md-image" width="828" height="504" loading="lazy" src="images/farmacocinetics.jpg" alt=""/>&#xA;&#xA;</a>&#xA;<h2 id="what-does-it-depend-on-whether-a-drug-works-and-its-side-effects">What does it depend on whether a drug works and its side effects?</h2>&#xA;As I mentioned earlier, whether or not a drug activates a cell&rsquo;s receptor depends on whether it fits its &ldquo;lock&rdquo;. This is defined by its three-dimensional structure. For this reason, if two drugs look alike, they are likely to cause similar effects, but being different, one of them will cause fewer side effects.&#xA;Generally a drug maintains a base structure, without which it has no effect, and small variations in that base structure are what determine the intensity of the therapeutic effect and the side effects. The difficult part is trying to deduce which combination will be the best.&#xA;<a href="images/analogos_penicilinas.jpg" aria-label="All penicillins have the yellow structure in common. These two differ in the part highlighted in red.">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="845" height="802" loading="lazy" src="images/analogos_penicilinas.jpg" alt="All penicillins have the yellow structure in common. These two differ in the part highlighted in red."/>&#xA; <figcaption>All penicillins have the yellow structure in common. These two differ in the part highlighted in red.</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;Look at the molecules above, a single change results in different behavior in the body, can you imagine how many variants we can have for a single drug? Each with different properties, structure and thus different intensities of therapeutic effect and with a unique combination of side effects.&#xA;What if instead of an Oxygen we use a sulfur, or if we remove the large hexagon-shaped structure on the left side (benzene) and replace it with two carbons? What if instead of two carbons we use three or four?&#xA;It is very difficult to predict this manually, but this is exactly where artificial intelligence can shine.&#xA;<h2 id="artificial-intelligence-and-drug-development">Artificial intelligence and drug development</h2>&#xA;Artificial intelligence is able to recognize patterns that humans cannot, it can analyze information related to a large number of molecules and their variants; their side effects, their three-dimensional structure, bioavailability, polarity, presence of functional groups and any other information already existing about each of these molecules, and use them to train a model that predicts whether a molecule has the potential to become a good drug candidate for further analysis and testing in animals and humans.&#xA;<a href="images/fluoxetin.png" aria-label="Fluoxetine, an antidepressant that acts by blocking a receptor.">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="960" height="927" loading="lazy" src="images/fluoxetin.png" alt="Fluoxetine, an antidepressant that acts by blocking a receptor."/>&#xA; <figcaption>Fluoxetine, an antidepressant that acts by blocking a receptor.</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;Of course AI for drug development will reach its full potential once the &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/the-rise-and-fall-of-the-ai-bubble/">AI bubble crashes</a>&#xA;.&#xA;<h2 id="what-parameters-should-i-use-to-train-an-artificial-intelligence-model-to-discover-new-drugs">What parameters should I use to train an artificial intelligence model to discover new drugs?</h2>&#xA;Well, that&rsquo;s the crux of the matter, the million dollar question. If you have never worked with biological systems and drugs, I suggest you read up on the basics of pharmacokinetics, pharmacodynamics and stereochemistry.&#xA;Cells are incredibly complex systems where there are countless parts interacting with each other. There is no simple answer to this question because it depends on the type of cell, the type of drug being used, and even such trivial factors as the type of diet and the time at which a drug is administered (chronopharmacology) can introduce noise in the behavior of drugs in a patient.&#xA;In addition, there are different approaches ranging from the three-dimensional structure, taking into account the functional groups or atoms that make up a molecule, as well as its multiple physicochemical properties, among which its solubility in lipids stands out, since it indicates how easily it will cross cell membranes; the greater the solubility in lipids, the greater the distribution in the body.&#xA;Most people think that chemistry is all about mixing things and seeing how the colors change, but in reality mathematics plays a fundamental role in chemistry and there are equations for everything from how to calculate how much to add of a substance to predicting how much of a substance remains in the body according to its physicochemical properties.&#xA;<h3 id="databases-for-available-drugs">Databases for available drugs</h3>&#xA;There are many, many databases available with information collected on many, many molecules that you can use to feed your models.&#xA;<ul>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://www.ebi.ac.uk/chembl/" rel="noopener" target="_blank">ChEMBL</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="http://cdb.ics.uci.edu/" rel="noopener" target="_blank">ChemDB</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://coconut.naturalproducts.net/" rel="noopener" target="_blank">COCONUT</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="http://www.dgidb.org/" rel="noopener" target="_blank">DGIdb</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="http://www.drugbank.ca/" rel="noopener" target="_blank">DrugBank</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="http://drugtargetcommons.fimm.fi/" rel="noopener" target="_blank">DTC</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="http://cbcb.cdutcm.edu.cn/INPUT/" rel="noopener" target="_blank">INPUT</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://pubchem.ncbi.nlm.nih.gov/" rel="noopener" target="_blank">PubChem</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="http://sideeffects.embl.de/" rel="noopener" target="_blank">SIDER</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="http://stitch.embl.de/" rel="noopener" target="_blank">STIITCH</a>&#xA;</li>&#xA;</ul>&#xA;I dare say that although the process will not be perfect and will be full of stumbles, given that the human body is a highly complex system, it will be much better than blindly searching through endless options.&#xA;If you are interested in the topic, a good place to start is this article titled &#xA;&#xA;<a class="markdown-link" href="https://www.sciencedirect.com/science/article/pii/S2162253123000392" rel="noopener" target="_blank">Artificial intelligence for drug discovery: Resources, methods, and applications</a>&#xA;&#xA;

The uses of artificial intelligence go beyond solving coding problems , and regardless of whether this artificial intelligence is conscious or not , it has endless applications. One of the most interesting applications for artificial intelligence is the development of new drugs. Bringing a new drug to market is an arduous, costly and, in most cases, unsuccessful process. Artificial intelligence can speed up the process enormously and narrow down the new drug candidates to a few, rather than dozens of them.

Artificial Intelligence & Drug Design for Developers

Composition over inheritance is a recurring theme in object-oriented programming. Usually, it is explained in a very complex way, but today I will try to simplify it to the point where purists will hate me.&#xA;Let&rsquo;s start, imagine you have a giant box of LEGO bricks, yes, those little plastic blocks that cause unimaginable pain when you step on them. But, in this case, we won&rsquo;t use them to cause pain but to build different types of cars.&#xA;<h2 id="inheritance-or-composition">Inheritance or composition</h2>&#xA;To build our tiny cars, there are two ways:&#xA;<ol>&#xA;<li>&#xA;Inheritance: you can start with a basic car design, and then make changes to it to create different types of cars. But sometimes this turn into a complete disaster, since you can end up with some strange cars that won&rsquo;t work properly.&#xA;</li>&#xA;<li>&#xA;Composition: Instead of starting with a basic car and changing it, you can use smaller LEGO pieces to build the different parts of a car, such as wheels, doors, and windows. Then put those pieces together to create different types of cars. This way, you have more control and flexibility to create exactly the type of car you want without making a mess.&#xA;</li>&#xA;</ol>&#xA;So, composition over inheritance means that it&rsquo;s often better to build things by putting smaller parts together rather than changing one big thing to make something new.&#xA;<h3 id="compositing-over-inheritance">Compositing over inheritance</h3>&#xA;And put in an example using Python code we would get something like:&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">&#xA;# Inheritance &#xA;class Car:&#xA; def start_engine(self):&#xA; print(&#34;Starting engine&#34;)&#xA;&#xA;class SportsCar(Car):&#xA; def start_engine(self):&#xA; print(&#34;Rrrrrrrr! Starting engine&#34;)&#xA;&#xA;# Composition &#xA;class Engine:&#xA; def start(self):&#xA; print(&#34;Starting engine&#34;)&#xA;&#xA;class Car:&#xA; def __init__(self):&#xA; self.engine = Engine()&#xA;&#xA; def start_engine(self):&#xA; self.engine.start()&#xA;&#xA;class SportsCar:&#xA; def __init__(self):&#xA; self.engine = Engine()&#xA;&#xA; def start_engine(self):&#xA; print(&#34;Vroooooom! Starting engine&#34;)&#xA;&#xA;# Using Composition&#xA;regular_car = Car()&#xA;regular_car.start_engine()&#xA;&#xA;fast_car = SportsCar()&#xA;fast_car.start_engine()&#xA;</code></pre></div>In the inheritance example, we started with a basic &ldquo;Car&rdquo; and modified it to make a &ldquo;SportsCar&rdquo;. In the compositing example, we build an &ldquo;Automobile&rdquo; and a &ldquo;SportsCar&rdquo; by combining smaller parts, such as the engine. It&rsquo;s like using LEGO pieces to build cars, and it gives us more control and flexibility when writing our programs.&#xA;

Composition over inheritance is a recurring theme in object-oriented programming. Usually, it is explained in a very complex way, but today I will try to simplify it to the point where purists will hate me.&#xA;Let&rsquo;s start, imagine you have a giant box of LEGO bricks, yes, those little plastic blocks that cause unimaginable pain when you step on them. But, in this case, we won&rsquo;t use them to cause pain but to build different types of cars.

Composition over inheritance in OOP simple explanation

<h2 id="what-is-a-deployment-pattern">What is a deployment pattern?</h2>&#xA;A deployment pattern (Not to be confused with a &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/design-patterns-in-software/">design pattern</a>&#xA;) is an automatic method of deploying new features of an application to your users. But it doesn&rsquo;t stop there, it is possible to get extra information from a deploy of an application, but&hellip;. but how?&#xA;Imagine you want to test a feature of your web application, but you are afraid that it will not be liked by your users, or you want to see if this new feature increases or decreases the conversion rate of your application, which is invaluable, especially in the early stages of iteration of an application.&#xA;What can you do in these cases? The best thing to do would be to test it on a representative sample of your audience and, depending on how it responds, discard it or roll it out to the rest of the users.&#xA;<h2 id="common-deployment-patterns">Common deployment patterns</h2>&#xA;There are a number of widely used deployment patterns:&#xA;<ul>&#xA;<li>Monolithic deployment</li>&#xA;<li>Microservices deployment</li>&#xA;<li>Containerization</li>&#xA;<li>Serverless Deployment</li>&#xA;<li>Continuous Integration (CI) / Continuous Deployment (CD)</li>&#xA;<li>Canary</li>&#xA;<li>Features toggles</li>&#xA;<li>Blue/Green</li>&#xA;<li>A/B Testing</li>&#xA;<li>Dark launches</li>&#xA;</ul>&#xA;For this post I am going to focus on the last patterns, since they are the ones I have read the least information about on the internet. Consider that deployment patterns can be combined with each other. For example, you can perform A/B tests on your monolithic application to find the best version. Having said that, I will explain the patterns.&#xA;<h3 id="canary-deployment">Canary deployment</h3>&#xA;This pattern consists of showing new features to a small group of users. After analyzing and correcting the performance of the new features and, if appropriate, the deploy is extended to all users.&#xA;<div class="mermaid">graph LR;&#xA; LoadBalancer-->Ver-1;&#xA; LoadBalancer-->Ver-2-Canary;&#xA;</div>&#xA; &#xA; &#xA; <h3 id="features-toggles-deployment">Features toggles deployment</h3>&#xA;Instead of releasing all changes at the same time, this pattern hides new features behind a switch, which can be turned on or off without modifying the code. This allows changes to be released gradually or only to certain users, making it easy to test and manage. This method has the advantage that if a problem occurs, you can turn the switch off without the need to return the code to a previous state.&#xA;<div class="mermaid">graph LR;&#xA; Server-- on/off --> Feature1;&#xA; Server-- on/off --> Feature2;&#xA;</div>&#xA; &#xA; &#xA; <h3 id="bluegreen-deployment">Blue/Green deployment</h3>&#xA;In the blue/green deployment we have two similar environments simultaneously. These environments will be known as blue and green. At any time only one of the two environments will be active, while load balancing from one environment to the other. If we find any errors we simply adjust the load balancing to the opposite side.&#xA;<div class="mermaid">graph LR;&#xA; LoadBalancer-->Stagging;&#xA; LoadBalancer-.->Production;&#xA;</div>&#xA; &#xA; &#xA; <h3 id="ab-testing-deployment">A/B testing deployment</h3>&#xA;A/B testing is the classic A/B testing; a random set of our users will receive version A of the application, while the rest will receive version B. We will then use statistics, specifically the two-sample t-test, to determine which version (A or B) is more effective.&#xA;The distribution percentage does not necessarily have to be 50-50.&#xA;<div class="mermaid">graph LR;&#xA; LoadBalancer-->VersionA-->30["30%"]-->Analysis;&#xA; LoadBalancer-->VersionB-->70["70%"]-->Analysis-->Statistics;&#xA;</div>&#xA; &#xA; &#xA; <h3 id="dark-launches-deployment">Dark launches deployment</h3>&#xA;This type of deployment pattern is quite similar to the Canary deployment, however in this case users must be aware that they are receiving a test version and must be aware of the new functionality being tested. With this knowledge the users will be able to provide feedback on the new functionality.&#xA;<div class="mermaid">graph LR;&#xA; LoadBalancer-->Normal;&#xA; LoadBalancer---|Inform the users|DarkLaunch;&#xA;</div>&#xA; &#xA; &#xA; Consider that many projects do not reach the necessary size for a deploy pattern to be useful, and that if your application has few users it may even be counterproductive. However, if this is not the case, you can use one or several of them to extract valuable information for your application.&#xA;

What is a deployment pattern? A deployment pattern (Not to be confused with a design pattern ) is an automatic method of deploying new features of an application to your users. But it doesn&rsquo;t stop there, it is possible to get extra information from a deploy of an application, but&hellip;. but how?&#xA;Imagine you want to test a feature of your web application, but you are afraid that it will not be liked by your users, or you want to see if this new feature increases or decreases the conversion rate of your application, which is invaluable, especially in the early stages of iteration of an application.

Common and Useful Deployment Patterns

This entry is about a design pattern of which, at the time, I found little to none information in Spanish. Imagine that you have a number of concurrent tasks that you want to perform, either crawling many websites, or perhaps processing information from each of the pixels of an image or anything else you can think of.&#xA;The simplistic option is to create a series of workers and use them concurrently, something like this pseudocode:&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">for job in jobs:&#xA; async process_concurrent_job()&#xA;</code></pre></div>This may look pretty good, at first, but it has multiple disadvantages; first, you will be creating workers without control, which can increase your program&rsquo;s memory usage incredibly fast; second, you are constantly creating and destroying workers, which can be costly for your program.&#xA;<a href="images/workers-vs-memoria.jpg" aria-label="If there is no worker limit, workers will continue to be created to match the tasks">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="605" height="340" loading="lazy" src="images/workers-vs-memoria.jpg" alt="If there is no worker limit, workers will continue to be created to match the tasks"/>&#xA; <figcaption>If there is no worker limit, workers will continue to be created to match the tasks</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;It would be best to keep memory usage constant and avoid creating and destroying workers frequently. For this, the worker pool pattern works perfect.&#xA;Worker pool is a &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/design-patterns-in-software/">design pattern</a>&#xA; that comes to make up for these shortcomings.&#xA;There are developers who have used this pattern to &#xA;&#xA;<a class="markdown-link" href="http://marcio.io/2015/07/handling-1-million-requests-per-minute-with-golang" rel="noopener" target="_blank">handle a million requests per minute on go.</a>&#xA;&#xA;<h2 id="how-does-the-worker-pool-design-pattern-work">How does the worker pool design pattern work?</h2>&#xA;Let&rsquo;s take a tail of a task by running, these can be fixed or dynamically created. Then, instead of creating and destroying multiple workers (&#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-introduction-to-goroutines-and-concurrency/">goroutines in the case of go</a>&#xA;) constantly, we create a fixed number of workers and put them in a cycle, in which they will be constantly listening for information from the queue (through a &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-use-of-channels-to-communicate-goroutines/">channel in the case of languages like Go</a>&#xA;). This way we will keep our memory management much more stable and predictable, in addition to limiting the impact of constant creation and destruction of workers.&#xA;Finally, we can optionally save the results of these tasks in a queue from which they can be read later.&#xA;<div class="mermaid">flowchart TD&#xA; Job_1-->JobQueue&#xA; Job_2-->JobQueue&#xA; Job_3-->JobQueue&#xA; subgraph WorkerPool&#xA; JobQueue-->|job|Worker_1&#xA; JobQueue-->|job|Worker_2&#xA; JobQueue-->|job|Worker_n&#xA; end&#xA;</div>&#xA; &#xA; &#xA; <h3 id="job-queue">Job queue</h3>&#xA;The tasks or jobs that we want to be executed by the workers will go to a task queue or job queue. A normal queue, like any other. This can be fixed, or created on the fly by means of user interactions or other systems.&#xA;<div class="mermaid">classDiagram&#xA;class JobQueue{&#xA; job 1&#xA; job 2&#xA; job 3&#xA; ...&#xA; job n&#xA;}&#xA;</div>&#xA; &#xA; &#xA; <h3 id="the-pool">The pool</h3>&#xA;The pool initializes and hosts the number of workers we set up, generally you will want to use a configuration file, environment variables or other means. Each of these workers will take a task, run it, and when it becomes available again, it will again look for a task from the job queue to run and repeat the cycle.&#xA;<div class="mermaid">flowchart TD&#xA; subgraph Pool&#xA; JobQueue-->|job|Worker_1&#xA; JobQueue-->|job|Worker_2&#xA; JobQueue-->|job|Worker_3&#xA; JobQueue-->|job|Worker_4&#xA; JobQueue-->|job|Worker_n&#xA; end&#xA;</div>&#xA; &#xA; &#xA; <h3 id="the-worker">The worker</h3>&#xA;The worker is in charge of executing the tasks and, as I mentioned, it will be listening for new tasks or jobs permanently or until a certain limit that we indicate, such as the job queue runs out, a given number of tasks are executed or any other condition that we declare.&#xA;<div class="mermaid">flowchart TD&#xA; A[The worker is initiliazed] --> B{Are pending jobs in the queue?}&#xA; B -->|yes| C[Get a new job]&#xA; C --> B&#xA; B ---->|No| E[End the worker]&#xA;</div>&#xA; &#xA; &#xA; The fixed number of workers will ensure that, during the entire program execution, there will be a maximum number of tasks running, which will limit the memory impact of our concurrent tasks.&#xA;<h3 id="the-worker-pools-results-queue-optional">The worker pool&rsquo;s results queue (optional)</h3>&#xA;Optionally, we can send the result of each task executed by a worker to a second queue; the result queue, which we can process later.&#xA;<div class="mermaid">classDiagram&#xA;class ResultsQueue{&#xA; result 1&#xA; result 2&#xA; result 3&#xA; ...&#xA; result n&#xA;}&#xA;</div>&#xA; &#xA; &#xA; This design pattern is very useful when huge amounts of tasks have to be processed and when we do not want to overload the system. And, as you can guess it is quite popular and useful in programming languages that heavily use concurrency, such as &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-programming-language-introduction-to-variables-and-data-types/">the Go programming language</a>&#xA;.&#xA;

This entry is about a design pattern of which, at the time, I found little to none information in Spanish. Imagine that you have a number of concurrent tasks that you want to perform, either crawling many websites, or perhaps processing information from each of the pixels of an image or anything else you can think of.&#xA;The simplistic option is to create a series of workers and use them concurrently, something like this pseudocode:

Worker Pool Design Pattern Explanation

Chat GPT is on everyone&rsquo;s lips, some are afraid of it, because of its &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/i-test-chatgpt-with-codewars-coding-challenges/">ability to solve code problems</a>&#xA; others are excited about its potential to change the world of work. Today I leave aside the economic consequences of AI and the question about whether &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/the-rise-and-fall-of-the-ai-bubble/">we&rsquo;re in an AI bubble or not</a>&#xA;, to focus on the philosophical aspect of Chat GPT and reflect a bit on the question: does Chat GPT really understand the language, is Chat GPT conscious?&#xA;<blockquote>&#xA;What a typical “learning machine” does, is finding a mathematical formula, which, when applied to a collection of inputs (called “training data”), produces the desired outputs. Adriy Burkov&#xA;</blockquote>&#xA;<h2 id="john-searles-the-chinese-room">John Searle&rsquo;s The Chinese Room</h2>&#xA;John Searle, was a scientist who wondered whether a computer can really understand language. And for this he designed a riveting thought experiment:&#xA;<a href="images/la-habitacion-china-de-searle.jpg" aria-label="Image of Searle&amp;rsquo;s Chinese Room generated with Dall-E">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="1024" height="1024" loading="lazy" src="images/la-habitacion-china-de-searle.jpg" alt="Image of Searle&amp;rsquo;s Chinese Room generated with Dall-E"/>&#xA; <figcaption>Image of Searle&#39;s Chinese Room generated with Dall-E</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;A human, inside a room completely isolated from the outside world, with a set of instructions to process symbols in Chinese and return a response. It should be noted that the person inside the room does not know the Chinese language and simply follows the set of instructions given to him, i.e., he does not understand the text coming in, nor the text going out.&#xA;<div class="mermaid">graph TD;&#xA; 沙悟淨-->Room;&#xA; Room-->西遊記;&#xA;</div>&#xA; &#xA; &#xA; Can you notice the similarities with a computer? They are quite obvious; there is an input, an output and a black box or computer program, the details of which would escape those outside this simplified little system.&#xA;<div class="mermaid">graph TD;&#xA; Input-->Program;&#xA; Program-->output;&#xA;</div>&#xA; &#xA; &#xA; According to Searle, to the people outside the room, whatever is inside seems to understand Chinese perfectly. However, we know that the person inside is just following a set of instructions, as complex as we like, but which does not involve an understanding of language, but a mechanical process. According to Searle, this situation is analogous to the operation of a computer.&#xA;<h3 id="is-chatgpt-conscious">Is ChatGPT conscious?</h3>&#xA;Extrapolating the above to ChatGPT; although a language model may produce responses that appear coherent and relevant, there is no evidence that it actually understands the language or is aware of its meaning.&#xA;According to Searle, ChatGPT may be following the most complex algorithm in existence but, according to Searle, there is no more awareness of the process there than we would find in the most sophisticated mechanical clock.&#xA;But then what makes the difference between a real intelligence and a mechanical process? is there such a difference?&#xA;<h2 id="are-consciousness-and-artificial-intelligence-related">Are consciousness and artificial intelligence related?</h2>&#xA;The highest representative of intelligence on earth is the human being (or at least our inflated ego tells us that), and it also happens that the human being is a living entity with consciousness. This leads us to the inevitable question: is a living being with consciousness necessary to have intelligence, or perhaps it is the other way around?&#xA;<h3 id="signs-of-intelligence-with-consciousness">Signs of Intelligence with consciousness</h3>&#xA;Some argue that consciousness and intelligence are related and that we would even have &#xA;&#xA;<a class="markdown-link" href="http://writing.rochester.edu/celebrating/2017/NAShonorable.pdf" rel="noopener" target="_blank">a gradient of consciousness as we advance in the complexity and intelligence of organisms</a>&#xA;. They give the label &ldquo;conscious&rdquo; to higher animals such as dolphins, orangutans, crows and other organisms that show traits of intelligence.&#xA;While others go further by saying that a system becomes more conscious the more intelligent it becomes, perhaps we could consider the example of &#xA;&#xA;<a class="markdown-link" href="https://www.bbc.com/mundo/noticias-61787944" rel="noopener" target="_blank">Blake Lemoine, who claimed that Google&rsquo;s artificial intelligence model had become conscious</a>&#xA;, or Giulio Tononi&rsquo;s integrated information theory, which proposes that consciousness is generated when a system is able to incorporate information and unify it, and that this level of consciousness (called Φ) can be calculated for any system.&#xA;<h4 id="the-problem-of-determining-whether-something-is-conscious-or-not">The problem of determining whether something is conscious or not</h4>&#xA;We also face the problem that consciousness can only be experienced by the conscious entity, there is no experiment that allows us to say for certain whether an entity is conscious or not. Without falling into an absolutist solipsism, we consider that the rest of human beings are conscious only because we know that we are conscious, not because we have irrefutable proof of it.&#xA;As Ludwig Wittgenstein stated in his book Philosophical Investigations:&#xA;<blockquote>&#xA;Imagine that at birth you are given a box with a beetle in it. It is a very valuable and extremely personal object, so much so that no one can see inside the box except oneself. Thus, there is no objective way to confirm that all boxes contain the same thing. In the best of cases they could contain a real beetle, but nothing guarantees one hundred percent that instead of the beetle there are not other insects, such as an ant or a spider, or that there is nothing at all, but whatever it is, it will always be considered under the term “beetle”.&#xA;</blockquote>&#xA;As long as we do not understand what consciousness is exactly, we cannot know that we have to “measure” to know if another entity is conscious, as long as it makes sense to talk about “measuring” when we talk about consciousness.&#xA;Translated with DeepL.com (free version)&#xA;<h3 id="signs-of-intelligence-without-consciousness">Signs of Intelligence without consciousness</h3>&#xA;Likewise, there are positions that defend that intelligence does not necessarily depend on consciousness, but that it can exist in systems that do not have subjective experience. For example, it is sufficient to cite Alpha Go and other computer programs that are capable of responding to complex stimuli, without existing beyond the game for which they were programmed, or &#xA;&#xA;<a class="markdown-link" href="https://publications.aap.org/pediatrics/article-abstract/111/1/e17/28494/Sleepwalking-and-Sleep-Terrors-in-Prepubertal?redirectedFrom=fulltext" rel="noopener" target="_blank">sleepwalkers, who can show signs of intelligence even when they are not conscious</a>&#xA;.&#xA;But even if human beings have unconscious processes capable of existing without the manifestation of consciousness&hellip; there must be something more than simple mechanical action, after all animals are much more complex than machines aren&rsquo;t they?&#xA;<h2 id="biological-automatons">Biological automatons</h2>&#xA;Sometimes we believe that only machines have a mechanical behavior and that any living being would be able to respond in a very different way than a machine would, with more versatility and adapting to changes, but is this always the case?&#xA;In the book &ldquo;Godel, Escher, Bach: An Eternal Golden Braid&rdquo; by Douglas R. Hofstader. The author cites an &#xA;&#xA;<a class="markdown-link" href="https://jhjeong.mindconnect.cc/Texts/sphex.html" rel="noopener" target="_blank">experiment in which a sphex wasp is tricked into bringing a cricket within the confines of a burrow up to 40 times</a>&#xA;. Just as if it were a computer program, this wasp gets stuck in an infinite loop from which it cannot escape, how different is this from a computer program that, after the same input, generates the same output?&#xA;As Hofstader rightly speculates, a human would have “stepped out” of the loop to stop for a few moments and investigate what was happening.&#xA;<a href="images/avisa-sphex.jpg" aria-label="Sphex wasp from the experiment mentioned in the book Godel, Escher, Bach: An Eternal Golden Braid">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="640" height="480" loading="lazy" src="images/avisa-sphex.jpg" alt="Sphex wasp from the experiment mentioned in the book Godel, Escher, Bach: An Eternal Golden Braid"/>&#xA; <figcaption>Sphex wasp from the experiment mentioned in the book Godel, Escher, Bach: An Eternal Golden Braid</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;This experiment made me question whether some living beings are nothing more than biological automatons and also where is the turning point at which a living being ceases to be an automaton and becomes conscious, are there gradients of consciousness? And, if so, what does consciousness look like beyond what we humans experience? If consciousness exists as a macroscopic manifestation, is it deterministic, or does it belong to the quantum world of indeterminacy? I don&rsquo;t know and I don&rsquo;t think the truth has yet to pick a winner.&#xA;<h2 id="what-to-read-or-watch-to-learn-more-about-artificial-intelligence-and-consciousness">What to read or watch to learn more about artificial intelligence and consciousness?</h2>&#xA;Consciousness is a complex subject that cannot be addressed in a few lines, not for nothing is it known as the &ldquo;hard problem&rdquo;, but if these brushstrokes left you wanting more, I leave you with my list of favorite resources to delve into this complex subject.&#xA;<ul>&#xA;<li>Godel, Escher, Bach: An Eternal Golden Braid by Douglas R. Hofstader: the author delves into the subject of self-reference and develops the question: can a system understand itself?</li>&#xA;<li>The Emperor&rsquo;s New Mind by Sir Roger Penrose: the author sets the context of the laws of the universe and analyzes whether consciousness and intelligence are related and whether they have a deterministic or non-deterministic character.</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://infinite.mit.edu/video/brains-minds-and-machines-consciousness-and-intelligence" rel="noopener" target="_blank">Brains, Minds, and Machines: Consciousness and Intelligence</a>&#xA;: MIT talk, where the topics of brains, consciousness, intelligence and machines are developed. Radically underrated; 7000 views on youtube alone? really?</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://www.youtube.com/watch?v=mC_KQC1gtWQ" rel="noopener" target="_blank">Can a program be alive?</a>&#xA; small video essay where one of my favorite youtubers develops the issue of whether a computer program can be alive.</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="http://writing.rochester.edu/celebrating/2017/NAShonorable.pdf" rel="noopener" target="_blank">The connection between intelligence and conciousness</a>&#xA;</li>&#xA;</ul>&#xA;

Chat GPT is on everyone&rsquo;s lips, some are afraid of it, because of its ability to solve code problems others are excited about its potential to change the world of work. Today I leave aside the economic consequences of AI and the question about whether we&rsquo;re in an AI bubble or not , to focus on the philosophical aspect of Chat GPT and reflect a bit on the question: does Chat GPT really understand the language, is Chat GPT conscious?

Chat Gpt, Searle's Chinese Room and consciousness

The &ldquo;reflect&rdquo; package is a useful library in the Go programming language that provides functions for working with reflection.&#xA;Hey! did you know that I wrote a completely Free Go programming language tutorial?, you can find it directly in the top menu bar or clicking this box. What is reflection in programming? Reflection is the ability of a program to inspect its own structure at runtime. This includes the ability to examine: types, values and metadata of objects in memory.

Go with Reflect: Boost Your Code's Flexibility

Almost all modern web applications perform some form of streaming, from video platforms to live streaming. In this post I explain how streaming works with HLS in such a simplified way that it will bring out your inner purist.&#xA;I leave you a minimal example of streaming in Go here in &#xA;&#xA;<a class="markdown-link" href="https://github.com/EduardoZepeda/go-hls-streaming-example" rel="noopener" target="_blank">my github repository</a>&#xA;, in case you want to see the code.&#xA;<h2 id="introduction-to-streaming">Introduction to streaming</h2>&#xA;Videos and audios contain a lot of encoded information, so their handling and downloading strongly impacts the bandwidth and usage of any server.&#xA;Streaming is a process that allows us to continuously send small amounts of information, in the case of audio or video, which can be stored or generated by a webcam or microphone in real time.&#xA;<h3 id="whats-wrong-with-the-http-protocol-for-playing-videos-and-audios">What&rsquo;s wrong with the HTTP protocol for playing videos and audios?</h3>&#xA;Normal users don&rsquo;t watch the complete audiovisual materials, yes, even you skip the paid advertising of your favorite influencers and sometimes you only watch 10 seconds of the video of some internet tutorials. If we were to use the HTTP protocol, the normal user would download a huge file, only to see a fraction of it. And he would have to wait for the download to complete before he could start playing it.&#xA;As you probably already know, sending the full video to all users would be pointless and consume huge amounts of bandwidth and I bet you don&rsquo;t want to make your cloud providers richer.&#xA;The solution? Streaming; an on-demand model, where each user receives only what they consume of the audio visual material, a little at a time, and if the user closes the video we do not send them the rest.&#xA;<h2 id="streaming-protocols">Streaming protocols</h2>&#xA;Before you start, you should know that there are quite a few streaming protocols, each with its own particularities that you can delve into on your own:&#xA;<ul>&#xA;<li>RTSP</li>&#xA;<li>RTP</li>&#xA;<li>RTCP</li>&#xA;<li>HLS</li>&#xA;<li>MPEG-DASH</li>&#xA;<li>HDS</li>&#xA;</ul>&#xA;I will explain HLS, why? Because HLS uses the HTTP protocol, so it does not require specialized servers, and it is compatible with any device that connects to the Internet. Finally, we add that lately it is a popular protocol for video streaming.&#xA;<h2 id="the-hls-protocol">The HLS protocol</h2>&#xA;The HLS protocol is a protocol based on HTTP, developed by Apple (yes, the same Apple), so any device that can connect to the Internet will be compatible with this protocol. HLS uses TCP underneath to send the information, avoiding the potential packet loss of its counterpart, UDP. And, as icing on the cake, HLS reacts to changes in internet speed and prioritizes the sending of lighter versions of our files (with lower quality, of course). The player in conjunction with the HLS library takes care of this automatically and you don&rsquo;t have to worry about the details.&#xA;<h2 id="preparation-of-the-files-for-hls-on-the-server">Preparation of the files for HLS on the server</h2>&#xA;Video transmission using HLS is carried out in several steps. First, the video is encoded and divided into segments of fixed duration. Then, these segments are uploaded to an HTTP server and provided to the user&rsquo;s media player via a playback index, a file with extension M3U8, which is a simple text file containing information about the available video segments. The segments can be uploaded to a CDN for higher performance, and some CDNs can even handle the entire process of encoding and segmenting your video.&#xA;To implement the protocol on the server side we need two steps:&#xA;<ul>&#xA;<li>Coding</li>&#xA;<li>Partitioning</li>&#xA;</ul>&#xA;<h3 id="coding">Coding</h3>&#xA;HLS requires our files to be in a specific encoding, so first we need to encode our media file to H.264 or H.265 (quite popular nowadays), so that any device can read them.&#xA;<div class="mermaid">flowchart LR&#xA; Video-->h.264&#xA; Video-->h.265&#xA;</div>&#xA; &#xA; &#xA; If your original file is not in that encoding, you can use tools like &#xA;&#xA;<a class="markdown-link" href="https://ffmpeg.org/" rel="noopener" target="_blank">ffmpeg</a>&#xA; to convert it.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">ffmpeg -i &lt;input&gt; -vcodec libx264 -acodec aac &lt;output.mp4&gt;&#xA;</code></pre></div><h3 id="partitioning-and-creating-an-index-for-hls">Partitioning and creating an index for HLS</h3>&#xA;Then, the video or audio that we need to place in streaming is divided into several parts, generally with a few seconds of duration and, in order to know in which order each part goes, an index will also be created.&#xA;<div class="mermaid">flowchart LR&#xA; Video-->index.m3u8&#xA; Video-->index0.ts&#xA; Video-->index1.ts&#xA; Video-->index2.ts&#xA; Video-->indexn.ts&#xA;</div>&#xA; &#xA; &#xA; Partitioning for HLS can also be performed with ffmpeg.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">ffmpeg -i &lt;tu-video&gt;.mp4 -profile:v baseline -level 3.0 -start_number 0 -hls_time 10 -hls_list_size 0 -f hls index.m3u8&#xA;</code></pre></div>The index that stores the order of each generated segment is a file with ending m3u8, whose content looks something like this:&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">#EXTM3U&#xA;#EXT-X-VERSION:3&#xA;#EXT-X-TARGETDURATION:13&#xA;#EXT-X-MEDIA-SEQUENCE:0&#xA;#EXTINF:10.333333,&#xA;index0.ts&#xA;#EXTINF:9.750000,&#xA;index1.ts&#xA;#EXTINF:13.458333,&#xA;index2.ts&#xA;#EXTINF:9.083333,&#xA;index3.ts&#xA;#EXTINF:9.208333,&#xA;index4.ts&#xA;#EXTINF:8.333333,&#xA;# ... RESTO DE FRAGMENTOS ...&#xA;#EXTINF:2.416667,&#xA;index24.ts&#xA;#EXT-X-ENDLIST&#xA;</code></pre></div>Each segment of the video is numbered in ascending order, each with a ts extension so that you know where it belongs.&#xA;<h2 id="hls-at-the-customer">HLS at the customer</h2>&#xA;That was the hardest part, now we just need to pass the index to our client and the client device will do the following:&#xA;<ol>&#xA;<li>Download the index,</li>&#xA;<li>Read the table of contents</li>&#xA;<li>Obtain the segment you require for the video according to the table of contents.</li>&#xA;<li>Add it to the playback queue</li>&#xA;<li>Read the index again to get the next segment and repeat the process.</li>&#xA;</ol>&#xA;All of the above with Javascript, the HLS player library is already developed and takes care of all this automatically.&#xA;<div class="mermaid">sequenceDiagram&#xA; participant Client&#xA; participant Server&#xA; Client->>Server: GET index.m3u8&#xA; Server->>Client: index.m3u8&#xA; Client->>Server: GET index0.ts&#xA; Server->>Client: index0.ts&#xA; Client->>Server: GET index1.ts&#xA; Server->>Client: index1.ts&#xA;</div>&#xA; &#xA; &#xA; <h3 id="example-of-hls-at-the-client">Example of HLS at the client</h3>&#xA;Look at this super simple example:&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-html" data-lang="html">&lt;script src=&#34;https://cdn.jsdelivr.net/npm/hls.js@latest&#34;&gt;&lt;/script&gt;&#xA;&lt;!-- Cargamos la librería mediante un CDN o tu propio servidor --&gt;&#xA;&lt;video controls id=&#34;video&#34;&gt;&lt;/video&gt;&#xA;&lt;!-- Cargamos la etiqueta de video --&gt;&#xA;</code></pre></div>And now we proceed to load the index, or in another way, the file&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-javascript" data-lang="javascript">var video = document.getElementById(&#39;video&#39;);&#xA; if(Hls.isSupported()) {&#xA; // Si soporta HlS &#xA; var hls = new Hls();&#xA; hls.loadSource(&#39;http://tuservidor.com/ruta/index.m3u8&#39;);&#xA; // carga el índice&#xA; hls.attachMedia(video);&#xA; //Una vez cargado el índice reproduce el video&#xA; hls.on(Hls.Events.MANIFEST_PARSED,function() {&#xA; video.play();&#xA; });&#xA; } else if (video.canPlayType(&#39;application/vnd.apple.mpegurl&#39;)) {&#xA; video.src = &#39;http://tuservidor.com/ruta/stream&#39;;&#xA; video.addEventListener(&#39;loadedmetadata&#39;,function() {&#xA; video.play();&#xA; });&#xA; }&#xA;</code></pre></div>If you were to examine the browser you would see that the video is loaded bit by bit, and as it is needed, the browser requests the next video segment and automatically adds it to the playback.&#xA;<a href="images/hls.jpg" aria-label="Download HLS index and video snippets in browser">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="1000" height="535" loading="lazy" src="images/hls.jpg" alt="Download HLS index and video snippets in browser"/>&#xA; <figcaption>Download HLS index and video snippets in browser</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;<h2 id="preprocessing-of-videos-for-hls-on-the-server">Preprocessing of videos for HLS on the server</h2>&#xA;If you will be in charge of processing the videos yourself, you may want to implement a service that will take care of encoding the videos to h.264 or h.265 and then split them into segments. After that you may want to link them to a notification system that lets your application know that the video processing is finished and can be played.&#xA;You may also want to have variants of the video with different quality, to be used in case of a slower connection on the client.&#xA;Of course, all of the above already depends on your architectural needs.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">#EXTM3U&#xA;#EXT-X-VERSION:6&#xA;#EXT-X-STREAM-INF:BANDWIDTH=1210000,RESOLUTION=480x360,CODECS=&#34;avc1.640015,mp4a.40.2&#34;&#xA;index-360p.m3u8&#xA;&#xA;#EXT-X-STREAM-INF:BANDWIDTH=2283600,RESOLUTION=640x480,CODECS=&#34;avc1.64001e,mp4a.40.2&#34;&#xA;index-480p.m3u8&#xA;&#xA;#EXT-X-STREAM-INF:BANDWIDTH=3933600,RESOLUTION=1280x720,CODECS=&#34;avc1.64001f,mp4a.40.2&#34;&#xA;index-720p.m3u8&#xA;</code></pre></div>With this you have the minimum to create a basic example and go from there on your own.&#xA;

Almost all modern web applications perform some form of streaming, from video platforms to live streaming. In this post I explain how streaming works with HLS in such a simplified way that it will bring out your inner purist.&#xA;I leave you a minimal example of streaming in Go here in my github repository , in case you want to see the code.&#xA;Introduction to streaming Videos and audios contain a lot of encoded information, so their handling and downloading strongly impacts the bandwidth and usage of any server.

Stream your videos and audios: HLS for your applications

In my post about &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/basic-characteristics-of-an-api-rest-api/">the basic features about a REST API</a>&#xA; I mentioned to you that, besides REST, there were other types of APIS, one of them is gRPC, which is derived from RPC, so let&rsquo;s start the post talking about the latter.&#xA;<h2 id="what-is-rpc">What is RPC?</h2>&#xA;RPC stands for Remote Procedure Call, which, in simple words, refers to invoking code execution on one machine from another machine, usually a server, in such a way that, to the programmer, it appears that the execution was performed locally.&#xA;<h3 id="how-does-rpc-work">How does RPC work?</h3>&#xA;The more detailed process is as follows:&#xA;<ol>&#xA;<li>The client makes the call by sending a message to the network.</li>&#xA;<li>The call includes a procedure to encode the methods, request types, and response type in the appropriate format.&#xA;request and response type in the appropriate format.&#xA;(&#xA;&#xA;<a class="markdown-link" href="https://es.wikipedia.org/wiki/Marshalling" rel="noopener" target="_blank">marshalling</a>&#xA;). This procedure is called the stub.</li>&#xA;<li>The server receives the request and uses the stub to decode the data into the appropriate format of the RPC environment and to know what to execute and with what information.</li>&#xA;<li>The task is executed on the server and a response is generated as a result.</li>&#xA;<li>The response from the server is encoded using the stub and sent to the client.</li>&#xA;<li>The client receives the response and decodes it in the appropriate format.</li>&#xA;</ol>&#xA;<a href="images/rpc-esquema.jpg" aria-label="Schematic diagram of gRPC operation">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="1080" height="669" loading="lazy" src="images/rpc-esquema.jpg" alt="Schematic diagram of gRPC operation"/>&#xA; <figcaption>Schematic diagram of gRPC operation</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;Did you notice I mentioned data encryption? Well, one aspect of RPC to note is that it requires both client and server to use the same programming language, which makes it a disadvantage in environments where multiple programming languages can be mixed.&#xA;Now, let&rsquo;s go to gRPC.&#xA;<h2 id="what-is-grpc">What is gRPC?</h2>&#xA;Google took into account the shortcomings of RPC and decided to improve it by creating gRPC.&#xA;gRPC emulates RPC with the advantage that it does not need to use the same programming language to perform machine-to-machine communication.&#xA;And what happened to data encryption? Well, Google developed Protocol Buffers (or protobuffers) to use them as the default format for gRPC in the exchange of information between machines and achieve better performance than other formats such as JSON or XML.&#xA;<h2 id="what-are-protobuffers">What are protobuffers?</h2>&#xA;You have probably worked with APIs and have noticed that, when communicating with an API, there is an exchange of information; you send information to the API and it returns a response. This exchange of information can take place in different formats, plain text, XML (if you are old school) or JSON (the most popular today).&#xA;For this exchange to occur, the information must be serialized when it is sent and then deserialized.&#xA;<div class="mermaid">graph TD;&#xA; JSON-- serialización -->data;&#xA; data-- deserialización -->JSON;&#xA;</div>&#xA; &#xA; &#xA; Protocol Buffers (protobuffers from now on) are a completely language and platform agnostic format, which gRPC uses to serialize and deserialize structured data only that, instead of using JSON, XML or another format, it is done directly in binary. This, as you know, makes it much more efficient than using a more human-friendly format like JSON.&#xA;<a href="images/protobuffers-grpc.jpg" aria-label="The compilation of the .proto file is unidirectional, while the serialization deserialization is bidirectional.">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="1400" height="800" loading="lazy" src="images/protobuffers-grpc.jpg" alt="The compilation of the .proto file is unidirectional, while the serialization deserialization is bidirectional."/>&#xA; <figcaption>The compilation of the .proto file is unidirectional, while the serialization deserialization is bidirectional.</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;<h3 id="how-to-convert-information-with-protobuffers">How to convert information with protobuffers?</h3>&#xA;Simplifying, to create the necessary code to serialize and deserialize in the protobuffers format we start from a file with extension .proto, this will be in charge of modeling the information that we will use to communicate, as well as the services that will be available for our API. Basically it is to tell you how our information is structured and what changes we are going to make on this information along with what they will receive as input and return as response.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">message DataResponse {&#xA; int32 id = 1;&#xA; string info = 2;&#xA; string result = 3;&#xA;}&#xA;&#xA;message DataRequest {&#xA; int32 id = 1;&#xA; string info = 2;&#xA;}&#xA;&#xA;service Publisher {&#xA; rpc ProcessData (DataRequest) returns (DataResponse) {}&#xA;}&#xA;</code></pre></div>After defining our models and services, these files are compiled, and will generate the necessary code to serialize and deserialize the information in the language we want, both on the client and server side. We do not have to worry about the details in this regard.&#xA;Currently the &#xA;&#xA;<a class="markdown-link" href="https://developers.google.com/protocol-buffers" rel="noopener" target="_blank">protobuffers format is available for C#, C++, Go, Objective-C, Java, Python and Ruby.</a>&#xA; Check the documentation for your particular language.&#xA;<h2 id="rest-vs-grpc">REST vs gRPC</h2>&#xA;But how efficient is gRPC compared to REST? Check out this comparison by &#xA;&#xA;<a class="markdown-link" href="https://laptrinhx.com/grpc-vs-rest-performance-comparison-2418648833/" rel="noopener" target="_blank">Matthew Leung</a>&#xA;.&#xA;<table>&#xA;<thead>&#xA;<tr>&#xA;<th></th>&#xA;<th>gRPC</th>&#xA;<th>REST</th>&#xA;</tr>&#xA;</thead>&#xA;<tbody>&#xA;<tr>&#xA;<td>Peticiones/Segundo</td>&#xA;<td>48.00</td>&#xA;<td>4.00</td>&#xA;</tr>&#xA;<tr>&#xA;<td>Latencia de la petición</td>&#xA;<td>6.15</td>&#xA;<td>8.00</td>&#xA;</tr>&#xA;<tr>&#xA;<td>CPU ms/s</td>&#xA;<td>832.00</td>&#xA;<td>404.00</td>&#xA;</tr>&#xA;<tr>&#xA;<td>CPU/petición</td>&#xA;<td>17.33</td>&#xA;<td>101.11</td>&#xA;</tr>&#xA;</tbody>&#xA;</table>&#xA;As you can see gRPC is much faster than REST plus JSON when processing requests, performance tests vary from 5 to 10 times.&#xA;<h3 id="why-is-grpc-so-efficient">Why is gRPC so efficient?</h3>&#xA;There are several factors that make gRPCs extremely efficient for exchanging information:&#xA;<ul>&#xA;<li>Uses protobuffers as a structure for data exchange.</li>&#xA;<li>The use of HTTP2 and multiplexing.</li>&#xA;<li>Compression of headers.</li>&#xA;</ul>&#xA;The binary format of the protobuffers translates into a smaller amount of information to be transported and easier and more efficient handling by computers.&#xA;On the other hand, the use of HTTP/2 allows gRPC to send multiple streams of information over a single TCP connection (multiplexing) in a bidirectional and asynchronous manner.&#xA;<h2 id="types-of-grpc-and-streaming">Types of gRPC and streaming</h2>&#xA;The HTTP/2 protocol is versatile and allows gRPC to support four types of client-server communications:&#xA;<ul>&#xA;<li>Unary. The client and server communicate using a simple request and response, as in REST.&#xA;response, as in REST.</li>&#xA;</ul>&#xA;<div class="mermaid">graph TD;&#xA; Client-->Server;&#xA; Server-->Client;&#xA;</div>&#xA; &#xA; &#xA; Server-side streaming. The server sends multiple responses to&#xA;a request from the client.&#xA;<div class="mermaid">graph TD;&#xA; Client-->Server;&#xA; Server-->Client;&#xA; Server-->Client;&#xA; Server-->Client;&#xA;</div>&#xA; &#xA; &#xA; <ul>&#xA;<li>Client-side streaming. The client sends multiple requests to the server&#xA;The client sends multiple requests to the server and the server responds with a single response.</li>&#xA;</ul>&#xA;<div class="mermaid">graph TD;&#xA; Client-->Server;&#xA; Client-->Server;&#xA; Client-->Server;&#xA; Server-->Client;&#xA;</div>&#xA; &#xA; &#xA; <ul>&#xA;<li>Two-way streaming**. Both the client and the server send multiple requests and&#xA;multiple requests and responses, respectively.</li>&#xA;</ul>&#xA;<div class="mermaid">graph TD;&#xA; Server-->Client;&#xA; Server-->Client;&#xA; Server-->Client;&#xA; Client-->Server;&#xA; Client-->Server;&#xA; Client-->Server;&#xA;</div>&#xA; &#xA; &#xA; As you can see this is super useful for services that require constant exchanges of large amounts of information, such as microservices.&#xA;<h2 id="other-grpc-capabilities">Other gRPC capabilities</h2>&#xA;<h3 id="interceptors">Interceptors</h3>&#xA;gRPC has a mechanism to intercept messages and modify them to your liking, you can think of it as a kind of middleware.&#xA;<h3 id="load-balancing">Load balancing</h3>&#xA;gRPC provides load balancing capabilities natively.&#xA;<h2 id="reference-resources">Reference resources</h2>&#xA;<ul>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://learn.microsoft.com/en-us/windows/win32/rpc/how-rpc-works" rel="noopener" target="_blank">How RPC works?</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://www.youtube.com/watch?v=gnchfOojMk4" rel="noopener" target="_blank">What&rsquo;s RPC an introduction guide</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://itnext.io/a-minimalist-guide-to-grpc-e4d556293422" rel="noopener" target="_blank">RPC minimalist guide</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://devopedia.org/grpc" rel="noopener" target="_blank">Devopedia</a>&#xA;</li>&#xA;</ul>&#xA;

In my post about the basic features about a REST API I mentioned to you that, besides REST, there were other types of APIS, one of them is gRPC, which is derived from RPC, so let&rsquo;s start the post talking about the latter.&#xA;What is RPC? RPC stands for Remote Procedure Call, which, in simple words, refers to invoking code execution on one machine from another machine, usually a server, in such a way that, to the programmer, it appears that the execution was performed locally.

Unleash Your API's Potential With gRPC and Protobuffers

ChatGPT is breaking with everything previously known in artificial intelligence, some developers are worried that it may replace them in their jobs, just as Github Copilot threatened at the time. In this post I test ChatGPT&rsquo;s supposed intelligence against three codewars challenges.&#xA;How does Codewars work? Before we start you need to understand that Codewars is a social network for programmers where code challenges written by the same users are shared.

I Test ChatGPT With Codewars Coding Challenges

In frameworks like &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/why-should-you-use-django-framework/">Django, migrations are created automatically</a>&#xA;, from the models. However, in languages like go, as long as we are not using an ORM, migrations will be done manually.&#xA;&#xA;&#xA;&#xA; <img width="60" height="60" src="https://res.cloudinary.com/dwrscezd2/image/upload/v1717959563/Go_gopher_favicon_uzxa20.svg" alt="">&#xA; <a target="_blank" rel=”nofollow” href="https://coffeebytes.dev/en/pages/go-programming-language-tutorial/">&#xA; Hey! did you know that I wrote a completely Free Go programming language tutorial?, you can find it directly in the top menu bar or clicking this box.</a>&#xA;&#xA;&#xA;<h2 id="what-is-a-database-migration">What is a database migration?</h2>&#xA;A migration is an abstraction to manage the state and changes that occur in a database. Instead of executing SQL statements one by one manually, we automate the process by writing all the necessary SQL and running it automatically.&#xA;A migration consists of two files with SQL statements:&#xA;<ul>&#xA;<li>file up: To make changes in the database.</li>&#xA;<li>down file: To revert changes in the database.</li>&#xA;</ul>&#xA;For this case they are called up and down, but you could give them any other names; such as forward and backward, or next and previous.&#xA;For example:&#xA;<a href="images/migrations.jpg" aria-label="Manually generated migration files">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="1200" height="700" loading="lazy" src="images/migrations.jpg" alt="Manually generated migration files"/>&#xA; <figcaption>Manually generated migration files</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;<h3 id="migrations-are-complementary">Migrations are complementary</h3>&#xA;Notice how the migrations are reversible and complementary; one performs an action and the other reverts it.&#xA;Following this logic we can make changes to the database and then revert them.&#xA;These two files can be generated automatically (as in the case of Django, from the models) or we can write them directly in SQL, as in the case of go.&#xA;<h2 id="migrate-installation">Migrate installation</h2>&#xA;To handle migrations we are going to use a tool called migrate, written in go.&#xA;Migrate can be downloaded directly from their &#xA;&#xA;<a class="markdown-link" href="https://github.com/golang-migrate/migrate/releases" rel="noopener" target="_blank">github releases section</a>&#xA;.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">curl -L https://github.com/golang-migrate/migrate/releases/download/v4.15.2/migrate.linux-amd64.tar.gz | tar xvz&#xA;mv migrate.linux-amd64 $GOPATH/bin/migrate&#xA;</code></pre></div>You should then be able to see which version you have installed.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">migrate -version&#xA;4.15.2&#xA;</code></pre></div><h2 id="migration-files-creation-with-migrate-in-go">Migration files creation with migrate in Go</h2>&#xA;To create the pair of migration files, which I told you about earlier, we run the following command:&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">migrate create -seq -ext=.sql -dir=./migrations &lt;nombre_de_la_migración&gt;&#xA;</code></pre></div>I explain what each flag does:&#xA;<ul>&#xA;<li>seq: indicates that it will be sequential, so that it begins with 000001 and continues until 00000n; the total of migrations that we have.</li>&#xA;<li>dir: will indicate the directory</li>&#xA;<li>ext: the extension of the file, in this case sql.</li>&#xA;<li>At the end the name we want the migration to have. I will use create_first_table for this example.</li>&#xA;</ul>&#xA;After executing the command, you will have two migration files, one with extension .up.sql and the other with extension .down.sql inside the migrations folder.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">ls&#xA;000001_create_first_table.up.sql 000001_create_first_table.down.sql&#xA;</code></pre></div>These files must be edited manually and the SQL statements must be placed inside them.&#xA;<h3 id="example-of-migrations-in-go-with-postgres">Example of migrations in go with postgres</h3>&#xA;For example, to create a hypothetical table users in a postgres database:&#xA;For the up:&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-sql" data-lang="sql">CREATE TABLE &#34;users&#34; (&#34;id&#34; serial NOT NULL PRIMARY KEY, &#34;name&#34; varchar(50) NOT NULL);&#xA;</code></pre></div>And, to reverse the above, there is the down file:&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-sql" data-lang="sql">DROP TABLE &#34;users&#34;;&#xA;</code></pre></div>Again, notice how both SQL statements are complementary; one creates a table and the other deletes it. But you can put more than one statement and they can be anything you want, an index, a constraint, a routine, etc.&#xA;<h2 id="execute-migrations-with-migrate-in-go">Execute migrations with migrate in Go</h2>&#xA;So far we have only created the migration files, but we have not let the program know where the database is.&#xA;Before making any changes to the database, we will need to indicate the access address to the database in the following format [engine]://[user]:[password]@[domain]/[database].&#xA;And, obviously, the most convenient and safest thing to do is to save this address in &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/linux-basic-commands-passwd-du-useradd-usermod-fdisk-lscpu-apt-which/">an environment variable</a>&#xA;.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">DATABASE=[engine]://[user]:[password]@[domain]/[database]&#xA;</code></pre></div>Now we have a database to connect to.&#xA;<h3 id="apply-migrations">Apply migrations</h3>&#xA;To apply all migrations we will use the up command. Migrate will automatically detect the numbering and run all migrations up in ascending order.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">migrate -path=./migrations -database=$DATABASE up&#xA;</code></pre></div><h3 id="remove-migrations">Remove migrations</h3>&#xA;On the other hand, to revert all migrations we will use the down command. Migrate will automatically detect the numbering and run all migrations down in descending order.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">migrate -path=./migrations -database=$DATABASE down&#xA;</code></pre></div><h3 id="go-to-a-specific-migration">Go to a specific migration</h3>&#xA;Whereas, if we want to go to a specific migration, we will use the goto command followed by the migration number to which we want to take the database.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">migrate -path=./migrations -database=$DATABASE goto &lt;migration number&gt;&#xA;</code></pre></div>Migrate will detect the active migration and run the corresponding up or down migrations to bring the database to that state.&#xA;<h2 id="the-migration-table">The migration table</h2>&#xA;And how does the tool know which migration it is in? After each change we make to the database, the migrate tool will store the state of our database in a table called schema_migrations that looks like this:&#xA;<a href="images/schema_migrations.png" aria-label="schema_migrations table in postgres&amp;quot;">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="219" height="71" loading="lazy" src="images/schema_migrations.png" alt="schema_migrations table in postgres&amp;quot;"/>&#xA; <figcaption>Migrations table where the current state is 1, selected in blue</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;<h3 id="column-version">Column version</h3>&#xA;Notice how the version column stores the status of the current migration. This way migrate records which version of the migrations it is in.&#xA;<h3 id="dirty-column">Dirty column</h3>&#xA;In addition, this table also contains a column called dirty that indicates if there was any conflict in the migration. In the latter case it will be necessary to repair it manually and force a new state in the table.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">migrate -path=./migrations -database=$DATABASE force 1&#xA;</code></pre></div><h2 id="migrations-to-remote-databases">Migrations to remote databases</h2>&#xA;The Migrate tool also supports remote migrations such as:&#xA;<ul>&#xA;<li>Filesystem</li>&#xA;<li>io/fs</li>&#xA;<li>Go-Bindata</li>&#xA;<li>pkger</li>&#xA;<li>GitHub</li>&#xA;<li>GitHub Enterprise</li>&#xA;<li>Bitbucket</li>&#xA;<li>Gitlab</li>&#xA;<li>AWS S3</li>&#xA;<li>Google Cloud Storage</li>&#xA;</ul>&#xA;Each of these endpoints requires a specific syntax. For example, the Amazon S3 endpoint looks like this:&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">migrate -source=&#34;s3://&lt;bucket&gt;/&lt;path&gt;&#34; -database=$DATABASE up&#xA;</code></pre></div>With this you already know the basics about migrations and you probably also value a lot more tools that take care of this automatically, such as Django, Ruby on Rails, South, etc.&#xA;

In frameworks like Django, migrations are created automatically , from the models. However, in languages like go, as long as we are not using an ORM, migrations will be done manually.&#xA;Hey! did you know that I wrote a completely Free Go programming language tutorial?, you can find it directly in the top menu bar or clicking this box. What is a database migration? A migration is an abstraction to manage the state and changes that occur in a database.

Go Migration Tutorial with migrate

Today I&rsquo;m going to talk about a topic that is often overlooked in most tutorials: handling application closing. What do I mean? To those times when you have to close an application, but there may be pending tasks running, open connections or you simply want to leave a record, in the form of a log, that the application was closed.&#xA;&#xA;&#xA;&#xA; <img width="60" height="60" src="https://res.cloudinary.com/dwrscezd2/image/upload/v1717959563/Go_gopher_favicon_uzxa20.svg" alt="">&#xA; <a target="_blank" rel=”nofollow” href="https://coffeebytes.dev/en/pages/go-programming-language-tutorial/">&#xA; Hey! did you know that I wrote a completely Free Go programming language tutorial?, you can find it directly in the top menu bar or clicking this box.</a>&#xA;&#xA;&#xA;<h2 id="signals-in-linux">Signals in Linux</h2>&#xA;As you probably already know, the Linux kernel is in charge of &ldquo;lending&rdquo; resources to go applications (or any other application) to run.&#xA;Because linux is the kernel of the system, it is able to call back those resources at any time and close the application.&#xA;Linux can &ldquo;nicely&rdquo; ask applications for the resources it lent them or &ldquo;take them away&rdquo; by force. To do this, Linux sends a series of signals to the application, some of which can be captured and handled by the application itself, with code in Go.&#xA;<h3 id="main-linux-signals">Main Linux signals</h3>&#xA;There are quite a few Linux signals, but here are the most important ones for this example:&#xA;<table>&#xA;<thead>&#xA;<tr>&#xA;<th>Signal</th>&#xA;<th>Value</th>&#xA;<th>Action</th>&#xA;<th>Comment</th>&#xA;<th>Command</th>&#xA;<th>Keyboard Shortcut</th>&#xA;</tr>&#xA;</thead>&#xA;<tbody>&#xA;<tr>&#xA;<td>SIGINT</td>&#xA;<td>2</td>&#xA;<td>Term</td>&#xA;<td>Interrupt from keyboard</td>&#xA;<td>kill -2 pid</td>&#xA;<td>CTRL+C</td>&#xA;</tr>&#xA;<tr>&#xA;<td>SIGTERM</td>&#xA;<td>15</td>&#xA;<td>Term</td>&#xA;<td>Terminate a process in a controlled manner</td>&#xA;<td>kill -15 pid</td>&#xA;<td>CTRL+C</td>&#xA;</tr>&#xA;<tr>&#xA;<td>SIGKILL</td>&#xA;<td>9</td>&#xA;<td>Term</td>&#xA;<td>Terminate a process in a forced manner, cannot be handled by</td>&#xA;<td>kill -9 pid</td>&#xA;<td></td>&#xA;</tr>&#xA;</tbody>&#xA;</table>&#xA;In Linux, these signals can be sent to an application via the &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/linux-basic-commands-passwd-du-useradd-usermod-fdisk-lscpu-apt-which/">kill command</a>&#xA;, specifying the value of the signal and the pid of the application.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">kill -&lt;valor&gt; &lt;pid&gt;&#xA;// kill -2 1234&#xA;</code></pre></div><h2 id="signal-handling-in-go">Signal handling in Go</h2>&#xA;In go, when we want to listen to the signals sent by the Linux kernel, we use the Notify method of the signal package. The Notify method will send our signal on a channel, which it will receive as the first argument. The second and third arguments are the signals that our method will listen for.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">func gracefulShutdown() {&#xA; quit := make(chan os.Signal, 1)&#xA; signal.Notify(quit, syscall.SIGINT, syscall.SIGTERM)&#xA; // ...&#xA;}&#xA;</code></pre></div><h3 id="managing-signals-with-channels">Managing signals with channels</h3>&#xA;Now we have a channel that receives our signal, but&hellip; what do we do with it?&#xA;Remember that, in go, &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-channels-understanding-the-goroutines-deadlocks/">operations that send or receive channel values are blocking inside their own goroutine</a>&#xA;, i.e., they keep code execution on hold?&#xA;In this case we are going to leave a variable expected by the value of the channel that we have just created, blocking the code at that point.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">func gracefulShutdown() {&#xA; quit := make(chan os.Signal, 1)&#xA; signal.Notify(quit, syscall.SIGINT, syscall.SIGTERM)&#xA; s := &lt;-quit&#xA; fmt.Println(&#34;Cerrando aplicación&#34;, s)&#xA; // ...&#xA;}&#xA;</code></pre></div>This way the application will wait until it receives any signal (SIGINT or SIGTERM) from Linux and, once it receives it, it will execute the rest of the function code.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">func gracefulShutdown() {&#xA; quit := make(chan os.Signal, 1)&#xA; signal.Notify(quit, syscall.SIGINT, syscall.SIGTERM)&#xA; s := &lt;-quit&#xA; fmt.Println(&#34;Cerrando aplicación&#34;, s)&#xA; // ... resto del código&#xA;}&#xA;</code></pre></div>Finally, for this function to run correctly, we need it to run inside its &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-introduction-to-goroutines-and-concurrency/">own goroutine</a>&#xA;. To do this, simply prefix the function call with the keyword go.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">func main() {&#xA; // ...&#xA; go gracefulShutdown()&#xA; // ...&#xA;}&#xA;</code></pre></div><h3 id="capturing-a-signit-signal">Capturing a SIGNIT signal</h3>&#xA;If we run a web server or any other permanent process and then issue a SIGNIT signal by pressing CTRL + C in the terminal or with the kill command, linux will receive the signal and notify our application to shut down.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">go run main.go&#xA;Empezando el servidor. Pid: 8830&#xA;&#xA;kill -2 8830&#xA;Cerrando el servidor: interrupt&#xA;</code></pre></div>Consider that the Pid may be different for you.&#xA;<h3 id="capturing-a-sigterm-signal">Capturing a SIGTERM signal</h3>&#xA;To emit a SIGTERM signal, we execute the GNU/Linux kill command, which will terminate the application. Our application will receive the signal through the channel and execute the rest of the code.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">go run main.go&#xA;Empezando el servidor. Pid: 9619&#xA;&#xA;kill -15 9616&#xA;Cerrando el servidor: terminated&#xA;</code></pre></div>Of course, ideally, you should go beyond printing a message and take care of all those tasks you want that require a more orderly completion process.&#xA;<h2 id="example-of-graceful-shutdown-with-a-web-server">Example of graceful shutdown with a web server</h2>&#xA;I leave you the complete example with a web server written entirely in go.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">package main&#xA;&#xA;import (&#xA; &#34;fmt&#34;&#xA; &#34;log&#34;&#xA; &#34;net/http&#34;&#xA; &#34;os&#34;&#xA; &#34;os/signal&#34;&#xA; &#34;syscall&#34;&#xA;)&#xA;&#xA;func getRoot(w http.ResponseWriter, r *http.Request) {&#xA; //io.WriteString(w, &#34;This is my website!\n&#34;)&#xA; w.Write([]byte(&#34;Este es mi sitio web!\n&#34;))&#xA;}&#xA;&#xA;func gracefulShutdown() {&#xA; quit := make(chan os.Signal, 1)&#xA; signal.Notify(quit, syscall.SIGINT, syscall.SIGTERM)&#xA; s := &lt;-quit&#xA; fmt.Println(&#34;Cerrando el servidor:&#34;, s)&#xA; os.Exit(0)&#xA;}&#xA;&#xA;func main() {&#xA; pid := os.Getpid() &#xA; fmt.Println(&#34;Empezando el servidor. Pid:&#34;, pid)&#xA; go gracefulShutdown()&#xA; http.HandleFunc(&#34;/&#34;, getRoot)&#xA; if err := http.ListenAndServe(&#34;:8000&#34;, nil); err != nil {&#xA; &#x9;log.Fatalf(&#34;El servidor fallo al iniciar. Error: %v&#34;, err.Error())&#xA; }&#xA;}&#xA;</code></pre></div>After running it, try to cancel the application with CTRL + C or with the terminal with the kill command, and see how the message is printed and the application is terminated in a more orderly and controlled manner.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">go run main.go&#xA;&#xA;CTRL + C&#xA;Empezando el servidor. Pid: 8830&#xA;Cerrando el servidor: interrupt&#xA;</code></pre></div>

Today I&rsquo;m going to talk about a topic that is often overlooked in most tutorials: handling application closing. What do I mean? To those times when you have to close an application, but there may be pending tasks running, open connections or you simply want to leave a record, in the form of a log, that the application was closed.&#xA;Hey! did you know that I wrote a completely Free Go programming language tutorial?

Go: Handling Signals for Closing Applications

With django and reportlab we can generate PDFs dynamically, using information from our database, user input or any other business logic we want.&#xA;Installation of reportlab The first thing will be to install reportlab, we can use pip, pipenv or any other package manager you want.&#xA;pip install reportlab # pip install reportlab Define PDF response type in Django Once installed, the first lines we will write will be to make sure that the browser knows that we will return a pdf, we will do it through an HTTP header, the Content-Type header, through the content_type variable.

Generating PDFs with Django and Reportlab

On Saturday, August 6, 2022 I sat for and approved my Microsoft Azure AZ-900 certification exam.&#xA;<h2 id="what-does-az-900-certification-consist-of">What does AZ-900 certification consist of?</h2>&#xA;The AZ-900 Fundamentals certification ensures that a person knows all the basic services that Microsoft&rsquo;s cloud, Azure, and its enterprise applications have.&#xA;For practical purposes, it prepares you to serve as an intermediary who recommends Microsoft Azure services to a company or third party, according to their needs. Or, as a software professional, you can take advantage of all the services that Azure has to offer. It often reads like a no-brainer, but Azure has a wealth of services.&#xA;To achieve the above you need to know the basic architecture of Azure, its different services: compute, storage, artificial intelligence, etc., their special features, differences, and their respective use cases.&#xA;<h2 id="my-examination-process">My examination process</h2>&#xA;The exam was conducted through the &#xA;&#xA;<a class="markdown-link" href="https://www.evaluaasi.com/" rel="noopener" target="_blank">Evaluaasi platform</a>&#xA;, through which you download a program that connects to a remote desktop to take the exam. This program will monitor your computer and connected devices, probably to prevent a user from cheating in some way; I have heard that some evaluation processes are so strict that they ask to see the room in which you will take the exam before starting. That wasn&rsquo;t my case though.&#xA;<a href="images/evaluaasi-plataforma.jpg" aria-label="Evaluaasi platform">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="1672" height="576" loading="lazy" src="images/evaluaasi-plataforma.jpg" alt="Evaluaasi platform"/>&#xA; <figcaption>Evaluaasi platform home screen</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;When it is time for the exam, and once connected to the remote desktop, an evaluator will enter his or her username and password to give you access to the exam.&#xA;According to what I was told in one of their emails, the application of the exam can be postponed and they are quite flexible.&#xA;<h2 id="az-900-examination-format">AZ-900 Examination format</h2>&#xA;The duration of the exam is approximately 60 minutes and has 45 questions, there are multiple choice questions, true or false, matching columns and even some where you have to choose an option from the Microsoft marketplace directly, just as if you were in the browser.&#xA;<a href="images/portal-azure.png" aria-label="Azure Portal screenshot">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="1051" height="209" loading="lazy" src="images/portal-azure.png" alt="Azure Portal screenshot"/>&#xA; <figcaption>Azure Portal</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;You can skip questions and mark them to come back to them later, which I highly recommend because time is tight, I had 10 minutes left over, but there were some questions I couldn&rsquo;t answer in the first round.&#xA;The test is divided into different sections, each with a different value, generally fluctuating around 20%.&#xA;At the end of the exam, the system automatically calculates your score and informs you if you approved. You need a minimum of 700 points out of a maximum of 1000 points to pass.&#xA;<h3 id="contents-of-the-az-900-exam">Contents of the AZ-900 exam</h3>&#xA;The exam is strongly oriented towards practical applications of cloud services. With questions focused on practical cases, where a fictitious company needs to decide which cloud service can best meet their needs, so it is not enough to know definitions, but to have a clear understanding of concepts, to be able to apply them in an environment a little more similar to the real one.&#xA;<h3 id="what-language-is-the-test-in">What language is the test in?</h3>&#xA;At the time of taking the exam it is possible to select from several languages, including English and Spanish, so don&rsquo;t worry if you think that language will be another barrier in this exam.&#xA;<h2 id="where-to-study-for-the-az-900-certification-exam">Where to study for the AZ-900 certification exam?</h2>&#xA;To study I used the following resources, here is a brief description of each one.&#xA;<h3 id="microsoft-learn">Microsoft Learn</h3>&#xA;The &#xA;&#xA;<a class="markdown-link" href="https://docs.microsoft.com/en-us/learn/" rel="noopener" target="_blank">microsoft Learn platform</a>&#xA; is the default resource, as there is no one better than microsoft to start reading the basic features of the Azure cloud. However, being a text-only solution it can become somewhat tedious. In addition, the large amount of information can make people who have their first approach to new technologies feel lost.&#xA;<a href="images/plataforma-microsoft-learn.jpg" aria-label="microsoft learn platform">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="951" height="914" loading="lazy" src="images/plataforma-microsoft-learn.jpg" alt="microsoft learn platform"/>&#xA; <figcaption>microsoft learning platform</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;The e-learning platform is also available in Spanish, just select the language.&#xA;See below for details on the content of this platform.&#xA;<h3 id="learnbigdata">Learnbigdata</h3>&#xA;Aprenderbigdata has a &#xA;&#xA;<a class="markdown-link" href="https://aprenderbigdata.com/az-900-azure-fundamentals/" rel="noopener" target="_blank">exam guide in 5 PDF files</a>&#xA; quite complete with questions in Spanish, which you can use as a review quiz, it is almost at the bottom of the page.&#xA;<a href="images/aprender-big-data.jpg" aria-label="Learn big data">&#xA;&#xA; <img class="md-image" width="1194" height="666" loading="lazy" src="images/aprender-big-data.jpg" alt="Learn big data"/>&#xA;&#xA;</a>&#xA;<h3 id="adam-marczacs-website">Adam Marczac&rsquo;s website</h3>&#xA;The &#xA;&#xA;<a class="markdown-link" href="https://marczak.io/az-900/" rel="noopener" target="_blank">Marczac website</a>&#xA; has a complete review of the AZ-900 certification content, organized into sections, along with an interactive form where you can test your knowledge on the spot, plus links to their youtube videos. I highly recommend it.&#xA;&#xA;&#xA; &#xA; <div style="position: relative; padding-bottom: 56.25%; height: 0; overflow: hidden;">&#xA; <iframe allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" allowfullscreen="allowfullscreen" loading="eager" referrerpolicy="strict-origin-when-cross-origin" src="https://www.youtube.com/embed/NPEsD6n9A_I?autoplay=0&controls=1&end=0&loop=0&mute=0&start=0" style="position: absolute; top: 0; left: 0; width: 100%; height: 100%; border:0;" title="AZ-900 | Microsoft Azure Fundamentals Full Course, Free Practice Tests, Website and Study Guides"&#xA; ></iframe>&#xA; </div>&#xA;&#xA;<h3 id="technical-preparation-from-john-savill">Technical preparation from John Savill</h3>&#xA;Among the resources I used to study I would like to highlight the following video by John Savill, as I found it to be the most complete and best explained:&#xA;&#xA;&#xA; &#xA; <div style="position: relative; padding-bottom: 56.25%; height: 0; overflow: hidden;">&#xA; <iframe allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" allowfullscreen="allowfullscreen" loading="eager" referrerpolicy="strict-origin-when-cross-origin" src="https://www.youtube.com/embed/tQp1YkB2Tgs?autoplay=0&controls=1&end=0&loop=0&mute=0&start=0" style="position: absolute; top: 0; left: 0; width: 100%; height: 100%; border:0;" title="AZ-900 Azure Fundamentals Study Cram - 2022 Edition! - OVER ONE MILLION VIEWS!"&#xA; ></iframe>&#xA; </div>&#xA;&#xA;It is a 3-hour review in English, in which they explain the basics of the Azure cloud, in a more structured and visual way. Like a giant blueprint of the cloud, in which they explain each part and how it relates to the others.&#xA;<h2 id="how-much-does-az-900-certification-cost-is-it-free">How much does AZ-900 certification cost? Is it free?</h2>&#xA;The certification costs about $90 USD directly with microsoft, but I got it for free as part of a &#xA;&#xA;<a class="markdown-link" href="https://platzi.com/r/eduardo-zepeda" rel="noopener" target="_blank">Platzi learning platform certification challenge</a>&#xA;.&#xA;I understand that if you sign up for the Microsoft Learn e-learning platform, they usually give away coupons from time to time.&#xA;With so many coupons and other free options, I don&rsquo;t recommend that you shell out the money out of pocket but wait for an opportunity to get it for free or much cheaper.&#xA;<h2 id="free-platzi-az-900-certification-process">Free Platzi AZ-900 certification process</h2>&#xA;A couple of months ago Platzi offered a challenge in which they give you the opportunity to certify yourself completely free of charge, through their platform, with two requirements: pass a series of courses on their platform, with their respective exams, and complete a Microsoft Learn practice lab.&#xA;<h3 id="required-platzi-courses">Required Platzi Courses</h3>&#xA;The process consists of completing the following 4 courses:&#xA;<ul>&#xA;<li>Fundamentals of Software Engineering</li>&#xA;<li>Introduction to the Terminal and Command Line Course</li>&#xA;<li>Linux Server Administration Course</li>&#xA;<li>Introduction to the Cloud with Azure Course</li>&#xA;</ul>&#xA;In general the first two are fairly easy, especially if you already have experience working with the &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/linux-basic-commands-grep-ls-cd-cat-cp-rm-scp/">usual linux commands from the terminal</a>&#xA;, the last two do require some experience or a lot of practice on your part to pass them.&#xA;<a href="images/administracion-servidores-linux.jpg" aria-label="Platzi&amp;rsquo;s Linux Server Administration Course">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="1283" height="801" loading="lazy" src="images/administracion-servidores-linux.jpg" alt="Platzi&amp;rsquo;s Linux Server Administration Course"/>&#xA; <figcaption>Linux Server Administration Course</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;<h3 id="microsoft-learn-practices">Microsoft Learn Practices</h3>&#xA;The practical laboratory is a series of 20 courses in which each course is subdivided into theory and practice. In the theoretical part you are shown the basics of the subject in written form, while the practical part consists of a short form of 3-4 questions in which the previous content is evaluated, but as a practical application.&#xA;For example, &ldquo;A company wants to implement a voting box where security is at its highest, which Microsoft Azure service would you recommend using.&rdquo;&#xA;<h2 id="azure-fundamentals-badge">Azure Fundamentals Badge</h2>&#xA;If you pass the exam, you will have access to the Microsoft AZ-900 Fundamentals badge, which you can register on Credly, or directly place your badge on a website, your LinkedIn profile or other medium.&#xA;This is mine, hosted on credly.&#xA;<figure><a href="https://www.credly.com/badges/17608a52-2cb7-4268-a907-613459559911/public_url"><img src="images%20microsoft-certified-azure-fundamentals.png"&#xA; alt="Azure AZ-900 certification badge by Eduardo Zepeda"></a>&#xA;</figure>&#xA;&#xA;

On Saturday, August 6, 2022 I sat for and approved my Microsoft Azure AZ-900 certification exam.&#xA;What does AZ-900 certification consist of? The AZ-900 Fundamentals certification ensures that a person knows all the basic services that Microsoft&rsquo;s cloud, Azure, and its enterprise applications have.&#xA;For practical purposes, it prepares you to serve as an intermediary who recommends Microsoft Azure services to a company or third party, according to their needs. Or, as a software professional, you can take advantage of all the services that Azure has to offer.

Azure AZ-900 Certification Exam: My Experience

A sitemap is an xml file that functions as a map to navigate your site. Hence the name; Site-map. Search engines, such as google, bing, yahoo and others, use the sitemap of a site as a starting point to analyze its content and include it in their search results.&#xA;A sitemap is &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/my-mistakes-regarding-the-tech-seo-optimization-of-my-website/">crucial in SEO and a sitemap with errors can plummet your site views</a>&#xA;, as it happened to me.&#xA;<h2 id="structure-of-a-sitemap">Structure of a sitemap</h2>&#xA;A sitemap is an xml file, which has an element called urlset, which is a collection of url elements. Each url element has a location, in this case its url address, a frequency of change, a priority and other optional elements, such as images.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-xml" data-lang="xml">&lt;?xml version=&#34;1.0&#34; encoding=&#34;UTF-8&#34;?&gt;&#xA;&lt;urlset xmlns=&#34;http://www.sitemaps.org/schemas/sitemap/0.9&#34; xmlns:xhtml=&#34;http://www.w3.org/1999/xhtml&#34;&gt;&#xA; &lt;url&gt;&#xA; &lt;loc&gt;http://example.com/objecto/1&lt;/loc&gt;&#xA; &lt;lastmod&gt;1970-01-01&lt;/lastmod&gt;&#xA; &lt;changefreq&gt;monthly&lt;/changefreq&gt;&#xA; &lt;priority&gt;0.8&lt;/priority&gt;&#xA; &lt;/url&gt;&#xA;&lt;/urlset&gt;&#xA;</code></pre></div><h3 id="split-sitemaps-for-simplicity">Split Sitemaps for simplicity</h3>&#xA;When a sitemap is very large it is possible to divide it into smaller sitemaps, using a sitemapindex element and sitemap sub elements, each with its respective location.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-xml" data-lang="xml">&lt;?xml version=&#34;1.0&#34; encoding=&#34;UTF-8&#34;?&gt;&#xA;&lt;sitemapindex xmlns=&#34;http://www.sitemaps.org/schemas/sitemap/0.9&#34;&gt;&#xA; &lt;sitemap&gt;&#xA; &lt;loc&gt;http://www.example.com/sitemap1.xml&lt;/loc&gt;&#xA; &lt;/sitemap&gt;&#xA; &lt;sitemap&gt;&#xA; &lt;loc&gt;http://www.example.com/sitemap2.xml&lt;/loc&gt;&#xA; &lt;/sitemap&gt;&#xA;&lt;/sitemapindex&gt;&#xA;</code></pre></div>But that&rsquo;s not all, you can divide it by category, by language or whatever fits the best for you.&#xA;<h2 id="framework-of-sitemaps-in-django">Framework of sitemaps in Django</h2>&#xA;Django already has an internal framework for sitemap generation, django.contrib.sitemaps, which allows us to create sitemaps dynamically in conjunction with django.contrib.sites.&#xA;django.contrib.sites is a framework included in django that allows you to manage different websites with the same django application.&#xA;To use the sitemaps framework, we need to add the two packages to the INSTALLED_APPS variable and also add the site identifier.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python"># settings.py&#xA;SITE_ID = 1&#xA;&#xA;INSTALLED_APPS = (&#xA; &#39;django.contrib.sites&#39;,&#xA; &#39;django.contrib.sitemaps&#39;,&#xA;)&#xA;</code></pre></div>Since Django keeps track of the sites that are managed by the application in the database, you will need to run migrations to update the database.&#xA;<h2 id="defining-a-sitemap-in-django">Defining a sitemap in Django</h2>&#xA;Now redirect to your application, at the same level as your models.py file and create a file called sitemaps.py.&#xA;Inside this file we are going to inherit a class from the Sitemap class provided by Django.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python"># app/sitemaps.py&#xA;from django.contrib.sitemaps import Sitemap&#xA;from .models import Videogame&#xA;&#xA;class VideogameSitemap(Sitemap):&#xA; changefreq = &#39;monthly&#39;&#xA; priority = 0.8&#xA;&#xA; def items(self):&#xA; return Videogame.objects.filter(published=True)&#xA;&#xA; def lastmod(self, obj):&#xA; return obj.modified&#xA;</code></pre></div><h3 id="items">items</h3>&#xA;By overwriting the items function we will define the queryset that will be used as a base, you can modify it as much as you want: partition it, limit it to attributes of your objects or as you prefer.&#xA;<h3 id="location">location</h3>&#xA;Location refers to the url of the resource. If we do not define a location method, Django will use the get_absolute_url method of our model to generate it.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python"># sitemaps.py&#xA;class VideogameSitemap(Sitemap):&#xA; # ...&#xA;&#xA; def location(self, obj):&#xA; return obj.customized_method()&#xA;</code></pre></div><h3 id="changefreq">changefreq</h3>&#xA;Refers to the frequency with which the content changes. You can use a function to generate it dynamically according to attributes of the object itself or leave it as a fixed value.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python"># app/sitemaps.py&#xA;class VideogameSitemap(Sitemap):&#xA;&#xA; def changefreq(self, obj):&#xA; # ...&#xA; return &#39;monthly&#39;&#xA;</code></pre></div><h3 id="priority">priority</h3>&#xA;It dictates the priority of the resource. It is possible to use a function to generate the priority dynamically through attributes or any other logic that you prefer.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python"># app/sitemaps.py&#xA;class VideogameSitemap(Sitemap):&#xA;&#xA; def priority(self, obj):&#xA; # ...&#xA; return 0.8&#xA;</code></pre></div><h2 id="adding-a-sitemap-to-django-urls">Adding a sitemap to Django urls</h2>&#xA;Now we have the sitemap, but we need to add it to the url in our project&rsquo;s urls.py file.&#xA;The view we will use, called sitemap, is provided by django and we just pass it a dictionary that relates to the sitemap we just created and pass it as a parameter.&#xA;Within the sitemaps variable you can add other sitemaps for other applications.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">from django.contrib.sitemaps.views import sitemap&#xA;from videogame.sitemaps import VideogameSitemap&#xA;&#xA;sitemaps = {&#xA; &#39;videogames&#39;: VideogameSitemap,&#xA;}&#xA;&#xA;urlpatterns = [&#xA; # ...&#xA; path(&#39;sitemap.xml&#39;, sitemap, {&#39;sitemaps&#39;: sitemaps},&#xA; name=&#39;django.contrib.sitemaps.views.sitemap&#39;),&#xA;]&#xA;</code></pre></div><h2 id="setting-the-domain-name-for-the-sitemap-in-django-admin">Setting the domain name for the sitemap in Django admin</h2>&#xA;If we access the sitemap, you will notice that the base url of the urls is example.org, to define another one we need to modify the base from the administrator. The form is located at /admin/sites/site/&#xA;<a href="images/Django-sitio-sitemap.png" aria-label="Add a domain to the Django sitemap">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="1291" height="528" loading="lazy" src="images/Django-sitio-sitemap.png" alt="Add a domain to the Django sitemap"/>&#xA; <figcaption>Modify the default domain of the sitemap in /admin/sites/site/</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;<h2 id="sitemap-cache">Sitemap cache</h2>&#xA;Remember that, generally, when you are creating a sitemap dynamically, from each of the objects in your database, you are going through it completely every time you access it. If your database is colossal, this may not be convenient because every access to the sitemap will hit the database, and trust me there are bots crawling the web several times a day.&#xA;Depending on the type of site you manage, you may want to store the sitemap in the &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/caching-in-django-rest-framework-using-memcached/">Django cache</a>&#xA;.&#xA;

A sitemap is an xml file that functions as a map to navigate your site. Hence the name; Site-map. Search engines, such as google, bing, yahoo and others, use the sitemap of a site as a starting point to analyze its content and include it in their search results.&#xA;A sitemap is crucial in SEO and a sitemap with errors can plummet your site views , as it happened to me.

Dynamic sitemap with django

As you probably already know, you should not use prints for debugging. The standard go logging library is much more versatile, it adds dates, filenames and other information, plus you can redirect the logs to standard output, to a file or wherever you want. This can make your debugging process more enjoyable and &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-basic-testing-and-coverage/">your go testing</a>&#xA; easier.&#xA;&#xA;&#xA;&#xA; <img width="60" height="60" src="https://res.cloudinary.com/dwrscezd2/image/upload/v1717959563/Go_gopher_favicon_uzxa20.svg" alt="">&#xA; <a target="_blank" rel=”nofollow” href="https://coffeebytes.dev/en/pages/go-programming-language-tutorial/">&#xA; Hey! did you know that I wrote a completely Free Go programming language tutorial?, you can find it directly in the top menu bar or clicking this box.</a>&#xA;&#xA;&#xA;<h2 id="log-println">Log Println</h2>&#xA;The log package is integrated into the standard logging library and its simplest function is Println which, for practical purposes, is like the standard Println but with some built-in benefits.&#xA;By default when logging something with go it will return the date and time, followed by the message we pass as an argument.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">log.Println(&#34;Mensaje&#34;)&#xA;// 2022/06/28 13:38:25 Mensaje&#xA;</code></pre></div>The Println method of log behaves exactly like the &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-functions-arguments-and-the-fmt-package/">fmt library</a>&#xA; method, so you can pass it multiple parameters and it will print them one by one.&#xA;<h2 id="flags-in-logging">Flags in logging</h2>&#xA;It is possible to change the default format in which the messages are displayed, change the order of the elements or add more information by calling the SetFlags method and passing it as arguments any of the flags provided by go.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">log.SetFlags(log.Ldate | log.Lshortfile)&#xA;log.Println(&#34;Mensaje&#34;)&#xA;// 2022/06/28 main.go:10: Mensaje&#xA;</code></pre></div>There are more flags available in addition to the above two.&#xA;<h3 id="flags-available">Flags available</h3>&#xA;Flags are available to show the full path to our file, the line number or to move the prefix and place it before the message. I leave them below.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">const (&#xA; Ldate = 1 &lt;&lt; iota &#xA; // Fecha en el tiempo local: 2009/01/23&#xA; Ltime &#xA; // Hora en el tiempo local: 01:23:23&#xA; Lmicroseconds &#xA; // Resolución en microsegundos: 01:23:23.123123. Asume Ltime.&#xA; Llongfile &#xA; // Ruta completa del archivo y número de linea: /a/b/c/d.go:23&#xA; Lshortfile &#xA; // Archivo y número de linea: d.go:23. Sobreescribe a Llongfile&#xA; LUTC &#xA; // Si ya están Ldate o Ltime usa UTC en lugar del tiempo local&#xA; Lmsgprefix &#xA; // Mueve el prefijo del principio de la linea y lo coloca antes del mensaje. &#xA; LstdFlags = Ldate | Ltime &#xA; // Los valores iniciales son Ldate y Ltime&#xA;)&#xA;</code></pre></div><h2 id="handling-errors-with-logging">Handling errors with logging</h2>&#xA;In addition to displaying information, it is possible to use methods, such as Panic and Fatal, to handle errors in our code.&#xA;<h3 id="logging-panic">Logging Panic</h3>&#xA;The log method has a Panic method that prints a message and calls the panic function.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">log.Panic(&#34;El sistema se paniquea&#34;)&#xA;</code></pre></div>Panic has two variants:&#xA;<ul>&#xA;<li>Panicf: The equivalent of Printf, for formatting with position operators.</li>&#xA;<li>Panicln: The equivalent of Println</li>&#xA;</ul>&#xA;<h3 id="logging-fatal">Logging Fatal</h3>&#xA;If we want to terminate the execution of our program immediately, without allowing the system to recover, we have at our disposal the Fatal method.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">log.Fatal(&#34;Error fatal ha ocurrido&#34;)&#xA;</code></pre></div>Like Panic, Fatal has two variants:&#xA;<ul>&#xA;<li>Fatalf: The equivalent of Printf, for formatting with position operators.</li>&#xA;<li>Fatalln: The equivalent of Println</li>&#xA;</ul>&#xA;<h2 id="redirecting-logging-output">Redirecting logging output</h2>&#xA;As I mentioned before, the library allows us to redirect, through its SetOutput method, the output of our logging to a destination; either the Stdout, the Stderr, the Stdin or even a file.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">log.SetOutput(os.Stdout)&#xA;</code></pre></div>In the example above we are redirecting it to the standard output.&#xA;<h3 id="redirecting-to-a-file">Redirecting to a file</h3>&#xA;To redirect our logs to a file, we first need to create it and then pass it as an argument to the SetOutput method, after that, all our logs will be written to our file and we will be able to retrieve them later.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">file, _ := os.Create(name: &#34;programa.log&#34;)&#xA;log.SetOutput(file)&#xA;log.Println(&#34;Mensaje a archivo&#34;)&#xA;file.Close()&#xA;</code></pre></div><h2 id="customized-loggers">Customized loggers</h2>&#xA;The log package allows us to create different types of loggers, using the New method, this method receives the following arguments; first, the destination of our logs, as you saw, this can be to the Stdout, the Stderr, the Stdin or a file; second, the prefix to show in each message; third, the flags with which we want to format our logs.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">infoLogger := log.New(os.Stdout, prefix: &#34;INFO: &#34;, flags)&#xA;</code></pre></div>Once our log is created, we can call its Println method to display it in the standard output.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">infoLogger.Println(&#34;Este es un mensaje de info&#34;)&#xA;</code></pre></div>

As you probably already know, you should not use prints for debugging. The standard go logging library is much more versatile, it adds dates, filenames and other information, plus you can redirect the logs to standard output, to a file or wherever you want. This can make your debugging process more enjoyable and your go testing easier.&#xA;Hey! did you know that I wrote a completely Free Go programming language tutorial?

Logging with the standard library in Go

Containers, especially Docker containers, are used everywhere, we tend to see them as small isolated operating systems that are inside our system. Using the Docker commands we can modify them, create them, delete them and even get inside them and run commands, but have you ever wondered how they work internally?&#xA;We know that a container is a linux process with several characteristics:&#xA;A linux process, or group of processes, executed by a user.

How Does a Docker Container Work Internally?

Solr, together with Lucene, is an outstanding search engine that allows you to perform searches with advanced features. In this post I bring you a summary of some of the most interesting features of Solr and Django Haystack.&#xA;I assume you already have a configured django app with Solr , in case you don&rsquo;t, check my previous post.&#xA;Behavior of default AND and OR searches Haystack allows us to define a default behavior for all searches, either by joining terms with AND or OR operators.

Autocomplete, Suggestions and Related Content: Solr and Django

Previously I explained you how to implement full text search in Django and trigrams-and-search-rank using Postgres. Solr comes to offer us something better, a robust, stable and feature-rich search engine, ready to use, in exchange for a little more complexity, more dependencies and having to include Java (yes, Java) in our project.&#xA;How does Solr work? Internally Solr uses Lucene, which is the search engine that is in charge of generating an index to make the queries and all the options related to the searches, Solr adds some extra functions and gives us a friendly interface to work with.

How to implement Solr for searches or queries in Django?

A git submodule is a record within a git repository that points to a commit in an external repository. They are handled exactly as you would with a repository, they even have a .git file that points to the location where a changelog is kept.&#xA;<a href="images/git-submodulo-esquema-basico.jpg" aria-label="Simplified outline of git submodules">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="1200" height="900" loading="lazy" src="images/git-submodulo-esquema-basico.jpg" alt="Simplified outline of git submodules"/>&#xA; <figcaption>Simplified outline of git submodules</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;git submodules are useful when we want to incorporate third-party code into a project and at the same time we want to keep strict control of the updates of that code through git. For example:&#xA;<ul>&#xA;<li>A shared repository for a theme or styles (As in SSG, Hugo).</li>&#xA;<li>A third-party library.</li>&#xA;<li>A repository that you want to use to create a &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/linux-basic-commands-grep-ls-cd-cat-cp-rm-scp/">Dockerfile in Docker</a>&#xA;.</li>&#xA;</ul>&#xA;On the other hand, using git submodules makes repository management quite complicated if you are not careful or if you work with many submodules, you have to pay attention to the context you are in and remember all the time the repository you are in.&#xA;<h2 id="adding-a-git-submodule-to-a-git-repository">Adding a git submodule to a git repository</h2>&#xA;To start using a submodule in an existing repository (our main repository) we use the command git submodule add, placing first the url of the submodule and then the folder where we want the submodule to be located.&#xA;If the directory does not exist it will be created.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">git submodule add &lt;url&gt; &lt;destination&gt;&#xA;</code></pre></div>The above command will copy the url <code>&lt;url&gt;</code> code into the specified <code>&lt;destination&gt;</code> directory.&#xA;<h3 id="structure-of-a-git-submodule">Structure of a git submodule</h3>&#xA;After adding a submodule to a repository a new file (not a directory) named .git will be created inside the submodule folder of our repository.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">.&#xA;├── .gitignore&#xA;├── .gitmodules&#xA;├── &lt;destination&gt;&#xA;│   ├── .git&#xA;│   ├── .gitignore&#xA;│   ├── app&#xA;│   │   ├── files.js&#xA;</code></pre></div>Depending on the repository you choose as a submodule, you will also see its own .gitignore file.&#xA;<h3 id="the-gitmodules-file">The .gitmodules file</h3>&#xA;In addition to copying the code from the remote repository into the target folder, git will create a .gitmodules file in the root of our main repository. This file stores the references to the submodule(s) of our repository.&#xA;Each of these submodules specifies its path, relative to the repository root, the url and the branch (optional).&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">[submodule &lt;destination&gt;]&#xA; path = &lt;destination&gt;&#xA; url = &lt;repository-url&gt;&#xA; [branch = &lt;rama&gt;]&#xA;</code></pre></div>This file is important because it is a reference to the submodules that our project needs to work.&#xA;<a href="images/funcionamiento-git-submodules.jpg" aria-label="git submodules operation schematic">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="1200" height="900" loading="lazy" src="images/funcionamiento-git-submodules.jpg" alt="git submodules operation schematic"/>&#xA; <figcaption>Schematic of git submodules operation</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;<h3 id="the-contents-of-a-submodules-git-file">The contents of a submodule&rsquo;s .git file</h3>&#xA;What does the submodule contain? If you go into any submodule, you will see that it has a file named .git.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">cd &lt;destination&gt;&#xA;ls -la &#xA;.rw-r--r-- 31 user 14 may 09:49 .git&#xA;# ...&#xA;</code></pre></div>If you check the contents of this file with the &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/linux-basic-commands-grep-ls-cd-cat-cp-rm-scp/">cat command</a>&#xA;, you will see that it is a path pointing to the .git/modules folder in our main repository. This is how git can keep track of submodules directly in the main repository.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">cat .git&#xA;gitdir: ../.git/modules/&lt;submodule&gt;&#xA;</code></pre></div>And what&rsquo;s at that location? In that location are the files with which git manages a repository internally, they keep the same structure as the ones inside the .git folder of your main repository.&#xA;<h3 id="git-treats-submodules-as-individual-repositories">Git treats submodules as individual repositories.</h3>&#xA;A submodule is handled in exactly the same way as a normal repository.&#xA;If you run the git status command inside a submodule, you will see that we are inside a different repository than the main one.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">git status&#xA;on main branch&#xA;Your branch is updated with &#39;origin/main&#39;&#xA;# ...&#xA;</code></pre></div>Within the submodule you can perform checkouts, create branches, even commits and pushes. All these changes will be made in the submodule repository, not in the main repository.&#xA;Git treats each submodule as if it were a separate repository, so each version of your main repository corresponds to a version of the submodule.&#xA;<a href="images/git-submodules-correspondencia.jpg" aria-label="Git submodules-correspondence">&#xA;&#xA; <img class="md-image" width="1200" height="630" loading="lazy" src="images/git-submodules-correspondencia.jpg" alt="Git submodules-correspondence"/>&#xA;&#xA;</a>&#xA;<h2 id="workflow-of-git-submodules">Workflow of git submodules</h2>&#xA;Every time you make a change within your submodule you must push the changes and then update the reference from the main repository to the submodules.&#xA;What happens if you don&rsquo;t? Well this is where the nightmare of all the people who hate submodules begins, you will be working on the latest version of the submodule, while your colleagues will be working on the old version.&#xA;<h3 id="steps-to-save-changes-in-a-git-submodule">Steps to save changes in a git submodule</h3>&#xA;How to solve it? With these three steps&#xA;<ol>&#xA;<li>Save the changes (commit) and push them to your submodule.</li>&#xA;<li>Return to your main repository.</li>&#xA;<li>Save the changes (commit) and push to your main repository.</li>&#xA;</ol>&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash"># Modifying submodule&#xA;git add &lt;files&gt;&#xA;git commit -m &#34;submodule&#39;s commit message&#34;&#xA;git push&#xA;&#xA;# Returning to your main repository.&#xA;cd &lt;main-repository&gt;&#xA;&#xA;# Save the changes (commit) and push to your main repository.&#xA;git add .gitmodules &lt;files&gt;&#xA;git commit -m &#34;Update to new submodule version&#34;&#xA;git push&#xA;</code></pre></div>The important thing to remember here is that we must always update changes to both the submodule and the main repository.&#xA;<h3 id="initializing-a-repository-with-a-git-submodule-in-git">Initializing a repository with a git submodule in git</h3>&#xA;What if instead of adding a submodule with git add submodule, we clone a project that has a .gitmodules file?&#xA;When cloning a repository that has submodules, git clones only the main repository, without including the content of the submodules.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">git clone &lt;repo-with-submodules&gt;&#xA;</code></pre></div>Check it, navigate inside the submodule folders and you will see that they are empty.&#xA;For git to download the content of the submodules we need to initialize, with &ndash;init the submodules with the following command:&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">git submodule update --init --recursive&#xA;</code></pre></div>The &ndash;recursive option will take care of initializing all the submodules of the main repository.&#xA;<h3 id="updating-a-repository-with-submodules-in-git">Updating a repository with submodules in git</h3>&#xA;What if we do a pull of our main project?&#xA;As I mentioned to you earlier, each version of your main project corresponds to a version of the submodule, so if the version of your project changed, the submodule it points to may have changed.&#xA;Also, in git, submodules are not automatically updated when you update the main repository.&#xA;If there were changes in your main repository and you do a git pull it is your obligation to update the submodules up to the most recent commit of the remote submodule code:&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">git submodule update --recursive --remote&#xA;</code></pre></div>With the above I conclude the article, if you found it useful you can share it in your favorite social networks.&#xA;

A git submodule is a record within a git repository that points to a commit in an external repository. They are handled exactly as you would with a repository, they even have a .git file that points to the location where a changelog is kept.&#xA;Simplified outline of git submodules git submodules are useful when we want to incorporate third-party code into a project and at the same time we want to keep strict control of the updates of that code through git.

Understand How Git Submodules Works and its Workflow

<h2 id="what-is-codewars">What is codewars?</h2>&#xA;Codewars is a social network of programmers who get together to challenge each other to solve code challenges. Codewars is one of the best websites for practicing algorithms and solving Katas. Katas? Yes, as in Karate.&#xA;<h3 id="what-are-katas-in-codewars">What are katas in codewars?</h3>&#xA;In the spirit of martial arts, more specifically Karate, these code problems are called katas. The katas are divided, ascendingly, according to their difficulty. There are katas from 8th kyu to 1st kyu, with 1st kyu being the most difficult type of kata of all.&#xA;There are katas on many, many topics: algorithm development, efficiency, regex, mathematics, cryptography, etc.&#xA;Collectively, the katas encompass a variety of languages: C, C++, Go, Python, Javascript, Elixir, Haskell, Rust, even languages as esoteric as Brainfuck. While, individually, each Kata has one or more languages.&#xA;Without further ado, here are my top 5 katas. These katas are not necessarily the most difficult ones, but the ones that I consider to have the ideal balance between creativity and difficulty. I choose those that give that feeling of a good puzzle, one of those that you can&rsquo;t stop until you solve it.&#xA;By the way, no, I&rsquo;m not going to post the answers, those are up to you.&#xA;<h2 id="multi-line-task-hello-world">Multi Line Task++: Hello World</h2>&#xA;You need to write a function that returns the string &ldquo;Hello, world!&rdquo; in Javascript.&#xA;Requirement: Each line must have at most 2 characters, and the total number of lines must be less than 40.&#xA;Hint: It is possible to complete it in only 28 lines of code.&#xA;Original Kata: &#xA;&#xA;<a class="markdown-link" href="https://www.codewars.com/kata/59a421985eb5d4bb41000031" rel="noopener" target="_blank">Multi Line Task++: Hello World</a>&#xA;&#xA;<h3 id="note-on-kata">Note on Kata</h3>&#xA;The difficult part is the two characters per line maximum. Give it a try.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-javascript" data-lang="javascript">12&#xA;34&#xA;56&#xA;78&#xA;//&#xA;</code></pre></div>There is a more complicated version where the limit is one character per line, in case you find this one too easy.&#xA;<h2 id="make-a-spiral">Make a spiral</h2>&#xA;Your task is to create a spiral of NxN with the given size.&#xA;For example, a spiral with 5 sides should look like this:&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-javascript" data-lang="javascript">00000&#xA;....0&#xA;000.0&#xA;0...0&#xA;00000&#xA;</code></pre></div>And size 10&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-javascript" data-lang="javascript">0000000000&#xA;.........0&#xA;00000000.0&#xA;0......0.0&#xA;0.0000.0.0&#xA;0.0..0.0.0&#xA;0.0....0.0&#xA;0.000000.0&#xA;0........0&#xA;0000000000&#xA;</code></pre></div>The return value should contain an array of arrays, 0&rsquo;s and 1&rsquo;s, with the first row consisting of 1&rsquo;s. For example, for the given size of 5, it should be:&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">[[1,1,1,1,1],[0,0,0,0,1],[1,1,1,0,1],[1,0,0,0,1],[1,1,1,1,1]]&#xA;</code></pre></div>For extreme cases of small spirals, the size will be at least 5.&#xA;As a general rule, the snake made of 1s cannot touch itself.&#xA;Original Kata: &#xA;&#xA;<a class="markdown-link" href="https://www.codewars.com/kata/534e01fbbb17187c7e0000c6" rel="noopener" target="_blank">Make a spiral</a>&#xA;&#xA;<h3 id="note-on-kata-1">Note on Kata</h3>&#xA;It looks easy, but I assure you it won&rsquo;t be so easy on your first try.&#xA;<h2 id="the-soul-of-wit-reverse-an-array">The soul of wit: reverse an array</h2>&#xA;No time for stories, invert an array (in Javascript), return the result. Do whatever you want with the original array. Don&rsquo;t use Array.prototype.reverse.&#xA;You have 30 bytes to spend.&#xA;Example: [1, 2, 3] → [3, 2, 1].&#xA;This time you won&rsquo;t be able to do the other Kata thing.&#xA;Nor can you use require.&#xA;Kata original: &#xA;&#xA;<a class="markdown-link" href="https://www.codewars.com/kata/59b81886460387d8fc000043" rel="noopener" target="_blank">The soul of wit: reverse an array</a>&#xA;&#xA;<h3 id="note-on-kata-2">Note on Kata</h3>&#xA;By 30 bytes it means that you have the equivalent in characters to use in your code. For example: the solution below has 33 characters, it exceeds the limit and also cannot be used reverse.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-javascript" data-lang="javascript">const reverse = a =&gt; a.reverse();&#xA;</code></pre></div><h2 id="last-digit-of-a-huge-number">Last digit of a huge number</h2>&#xA;Given a list [x1, x2, x3, &hellip;, xn] compute the last digit (decimal) of x1 ^ (x2 ^ (x3 ^ (&hellip; ^ xn))).&#xA;Example:&#xA;lastDigit([3, 4, 2]) === 1&#xA;because 3 ^ (4 ^ 2) = 3 ^ 16 = 43046721.&#xA;Beware: powers grow incredibly fast. For example, 9 ^ (9 ^ 9) has more than 369 million digits. Your lastDigit function has to deal with those numbers efficiently.&#xA;Unusual cases: we assume that 0 ^ 0 = 1 and that the last digit of an empty list is equal to 1.&#xA;Kata original: &#xA;&#xA;<a class="markdown-link" href="https://www.codewars.com/kata/5518a860a73e708c0a000027" rel="noopener" target="_blank">Last digit of a huge number</a>&#xA;&#xA;<h3 id="note-on-kata-3">Note on Kata</h3>&#xA;If you are thinking of writing something like:&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">def lastDigit(arr):&#xA; # Esta función NO es la correcta&#xA; total = 1&#xA; for element in arr[::-1]:&#xA; total = element ** total&#xA;&#xA; return str(total)[-1]&#xA;&#xA;last_digit([528374,27415,789392,462589,166837,699678,866982])&#xA;</code></pre></div>Solutions like this will get you nowhere, the Kata has to run incredibly fast.&#xA;See how long it takes to run in Python with the correct lastDigit function.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">time python script.py &#xA;&#xA;real 0m0.122s&#xA;user 0m0.073s&#xA;sys&#x9; 0m0.044s&#xA;</code></pre></div>If you try to run the above code you can probably go make a cup of coffee before it finishes executing.&#xA;<h2 id="escape-the-maze">Escape the maze</h2>&#xA;You are provided with a complete labyrinth, like a 2-dimensional grid, more specifically in your language: an array of strings.&#xA;maze[0][0] is the upper left corner&#xA;maze[maze[maze.length - 1][maze[0].length - 1] is the lower right corner&#xA;Within this 2D grid:&#xA;<pre tabindex="0"><code>&#39; &#39; Espacio que puedes recorrer&#xA;&#39;#&#39; Es un arbusto de espinas (No puedes cruzarlo)&#xA;&#39;^&#39;, &#39;&lt;&#39;, &#39;v&#39; or &#39;&gt;&#39; Tu cuerpo mirando hacía la parte superior, izquierda, inferior, o derecha, respectivamente, del mapa.&#xA;</code></pre>Original Kata: &#xA;&#xA;<a class="markdown-link" href="https://www.codewars.com/kata/5877027d885d4f6144000404" rel="noopener" target="_blank">Escape the maze</a>&#xA;&#xA;<h3 id="note-on-kata-4">Note on Kata</h3>&#xA;You are given a series of mazes, your position and you must provide an array of moves to get out. It&rsquo;s incredibly entertaining!&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">[ &#39;##########&#39;,&#xA; &#39;# #&#39;,&#xA; &#39;# ##### #&#39;,&#xA; &#39;# # # #&#39;,&#xA; &#39;# #^# # #&#39;,&#xA; &#39;# ### # #&#39;,&#xA; &#39;# # #&#39;,&#xA; &#39;######## #&#39; ]&#xA;</code></pre></div><h2 id="katas-with-honorable-mention">Katas with honorable mention</h2>&#xA;There are other Katas that I like very much but they were left out of this top. Check them out.&#xA;<ul>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://www.codewars.com/kata/53d40c1e2f13e331fc000c26" rel="noopener" target="_blank">The Millionth Fibonacci Kata</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://www.codewars.com/kata/59122604e5bc240817000016" rel="noopener" target="_blank">Prime Streaming [NC-17]</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://www.codewars.com/kata/544e5d75908f2d5eb700052b" rel="noopener" target="_blank">Breaking the Vigenère Cipher</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://www.codewars.com/kata/5877027d885d4f6144000404" rel="noopener" target="_blank">Escape the Maze</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://www.codewars.com/kata/56bb9b7838dd34d7d8001b3c" rel="noopener" target="_blank">Simple Maze</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://www.codewars.com/kata/5324945e2ece5e1f32000370" rel="noopener" target="_blank">Sum strings as numbers</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://www.codewars.com/kata/56fa9cd6da8ca623f9001233" rel="noopener" target="_blank">Elemental words</a>&#xA;</li>&#xA;</ul>&#xA;

What is codewars? Codewars is a social network of programmers who get together to challenge each other to solve code challenges. Codewars is one of the best websites for practicing algorithms and solving Katas. Katas? Yes, as in Karate.&#xA;What are katas in codewars? In the spirit of martial arts, more specifically Karate, these code problems are called katas. The katas are divided, ascendingly, according to their difficulty. There are katas from 8th kyu to 1st kyu, with 1st kyu being the most difficult type of kata of all.

REST API: Best practices and design

This publication is a minimal guide of practical tips on REST API design, I don&rsquo;t go too deep into the theory. On top of that, I may oversimplify many concepts in order to keep the text as short and simple as possible.&#xA;In the next post I will talk about some more subjective questions such as: how to return JSON correctly, how much to nest an API, what are the ways to version a REST API, and what are some of the ways to version a REST API.

REST API basic characteristics and recommendations

Grouping by categories is quite common in web applications, from movies, courses or any other resource that presents a hierarchical relationship to another object. In Django there are different ways to model these relationships. Probably, the first that will come to your mind will be to create a category object, and then relate it by means of a ForeignKey with a subcategory.&#xA;<h2 id="one-subcategory-or-level-per-model">One subcategory or level per model</h2>&#xA;What I meant by one category or level per model is something like this:&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python"># app/models.py&#xA;from django.db import models&#xA;&#xA;class Category(models.Model):&#xA; name = models.CharField(max_length=256)&#xA; # other properties&#xA;&#xA;class SubCategory(models.Model):&#xA; name = models.CharField(max_length=256)&#xA; # other properties&#xA; category = models.ForeignKey(Category, related_name=&#34;subcategories&#34;, blank=True, null=True, on_delete=models.CASCADE)&#xA;</code></pre></div>This approach to the hierarchy problem in Django looks good at first glance. The resulting structure will look something like this:&#xA;<a href="images/CategoriaDjango-1.jpg" aria-label="Subcategory model schema with ForeignKey made Category in Django">&#xA;&#xA; <img class="md-image" width="1000" height="400" loading="lazy" src="images/CategoriaDjango-1.jpg" alt="Subcategory model schema with ForeignKey made Category in Django"/>&#xA;&#xA;</a>&#xA;<h3 id="the-problem-of-using-a-model-by-category">The problem of using a model by category</h3>&#xA;This scheme will work in situations where the hierarchies do not nest very deep, but what if those subcategories have subcategories?&#xA;Imagine a horror movie category, with a ghost subcategory that, in turn, has a home ghost subcategory and this, in turn, a subcategory of type of ending.&#xA;Well, we add a SubSubCategory class, don&rsquo;t we? But&hellip; what if those SubSubCategories have in turn subcategories. See what I&rsquo;m trying to get at?&#xA;<a href="images/ProblemaCategoriasDjango.jpg" aria-label="Infinite subcategories problem scheme">&#xA;&#xA; <img class="md-image" width="1000" height="850" loading="lazy" src="images/ProblemaCategoriasDjango.jpg" alt="Infinite subcategories problem scheme"/>&#xA;&#xA;</a>&#xA;Every time you need to create a new subcategory you will have to create a new model in the models.py file of your application. And not only that, but a new table that probably only has a few records. Is there a better approach to the problem? The &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/why-should-you-use-django-framework/">versatile Django Framework&rsquo;s ORM</a>&#xA; offers a pretty clean solution.&#xA;<h2 id="foreignkey-to-the-same-model-in-django">ForeignKey to the same model in Django</h2>&#xA;To simplify the problem of categories in Django, we create a single model, with a property of type ForeignKey or foreign key pointing to the same object; that is, to self.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python"># app/models.py&#xA;from django.db import models&#xA;&#xA;class Category(models.Model):&#xA; name = models.CharField(max_length=256)&#xA; parent = models.ForeignKey(&#xA; &#34;self&#34;,&#xA; related_name=&#34;subcategories&#34;,&#xA; on_delete=models.CASCADE,&#xA; blank=True,&#xA; null=True,&#xA; )&#xA;</code></pre></div>In this way we will have a structure similar to a graph, where each node points to another.&#xA;<a href="images/ForeignKeyASelfEsquemaDjango.jpg" aria-label="Schematic diagram of how ForeignKey made self(the same model) works in Django">&#xA;&#xA; <img class="md-image" width="1000" height="850" loading="lazy" src="images/ForeignKeyASelfEsquemaDjango.jpg" alt="Schematic diagram of how ForeignKey made self(the same model) works in Django"/>&#xA;&#xA;</a>&#xA;This new arrangement allows us to create as many subcategories as we want, without the need to create new models. To do so, we simply assign the parent property to the Category class instance we want it to belong to.&#xA;<h3 id="accessing-the-same-model-in-django">Accessing the same model in Django</h3>&#xA;See how the ForeignKey does self in practice:&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">from my_app.models import Category&#xA;parent = Category.objects.create(name=&#34;Programming languages&#34;)&#xA;subcategory = Category.objects.create(name=&#34;Python&#34;)&#xA;subcategory.parent = parent&#xA;# save it in the database&#xA;subcategory.save()&#xA;</code></pre></div>I explain what happens. First we create a main category, and a subcategory. Later, we assign the property parent, of this last one, to the main category. And ready, we save.&#xA;Finally, let&rsquo;s create a sub-subcategory for our subcategory&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">subsubcategory = Category.objects.create(name=&#34;Django&#34;)&#xA;subsubcategory.parent = subcategory&#xA;subsubcategory.save()&#xA;</code></pre></div>Notice how we have created another sub-subcategory (called Django), which comes from the same model we used in the other two. To assign it to a category, we match its parent property to the subcategory we created (named Python).&#xA;As you have already seen, a single model allows us to add as many subcategories as we want.&#xA;<h3 id="access-to-subcategories">Access to subcategories</h3>&#xA;If we examine the parent category, which we created previously, we will notice that it has a list of subcategories, among which our subcategory (Call Python) is already included.&#xA;We can access it as we would any other many-to-one relationship.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">parent.subcategories.all()&#xA;&lt;QuerySet [&lt;Category: Category object (2)&gt;]&gt;&#xA;parent.subcategories.all()[0].name&#xA;&#39;Python&#39;&#xA;</code></pre></div><h3 id="go-from-subcategories-to-categories">Go from subcategories to categories</h3>&#xA;On the other hand, if we want to go &ldquo;in reverse&rdquo; from the most nested category to the least nested, we simply go through it; we access the parent, and then the parent of the next instance, and so on as many nestings as we need.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">subcategory.name&#xA;&#39;Django&#39;&#xA;subcategory.parent.name&#xA;&#39;Python&#39;&#xA;subcategory.parent.parent.name&#xA;&#39;Programming languages&#39;&#xA;</code></pre></div><h2 id="other-resources">Other resources</h2>&#xA;<ul>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://docs.djangoproject.com/en/4.0/ref/models/fields/" rel="noopener" target="_blank">Official documentation on the ForeignKey to self</a>&#xA;</li>&#xA;</ul>&#xA;

Grouping by categories is quite common in web applications, from movies, courses or any other resource that presents a hierarchical relationship to another object. In Django there are different ways to model these relationships. Probably, the first that will come to your mind will be to create a category object, and then relate it by means of a ForeignKey with a subcategory.&#xA;One subcategory or level per model What I meant by one category or level per model is something like this:

Categories in Django using ForeignKey to self

Debounce and throttle are &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/design-patterns-in-software/">design patterns</a>&#xA; used to limit the execution of functions, generally they are used to restrict the amount of times an event is fired: click, scroll, resize or other events. Patterns are not exclusive to Javascript; in a previous post I explained how to use throttle to &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/throttling-on-nginx/">limit the number of requests received by the nginx server</a>&#xA;.&#xA;Both patterns generate a function that receives a callback and a timeout or delay.&#xA;<h2 id="debounce-pattern">Debounce Pattern</h2>&#xA;The debounce pattern postpones the execution of a function until a certain waiting time has elapsed.&#xA;Further attempts to execute the function will cancel the pending execution and restart the timeout.&#xA;<a href="images/Bounce-design-pattern-programming.png" aria-label="Simplified debounce pattern schematic">&#xA;&#xA; <img class="md-image" width="1200" height="1200" loading="lazy" src="images/Bounce-design-pattern-programming.png" alt="Simplified debounce pattern schematic"/>&#xA;&#xA;</a>&#xA;<h3 id="debounce-pattern-explanation">Debounce pattern explanation</h3>&#xA;The code for debounce in javascript looks like this:&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-javascript" data-lang="javascript">const debounce = (callback, waitTimeInMs) =&gt; {&#xA; let timeout &#xA; return (...args) =&gt; {&#xA; clearTimeout(timeout)&#xA; timeout = setTimeout(()=&gt; callback(...args), waitTimeInMs)&#xA; }&#xA;}&#xA;</code></pre></div>Our debounce function returns a function, which will receive any number of arguments (&hellip;args).&#xA;This function uses a closure to access the variable timeout. What is timeout? timeout is a setTimeout function, which schedules the execution of our callback for later execution.&#xA;But now pay attention to the clearTimeout. Every time we call the debounce function it will clear any scheduled function, so the only way for our callback to run is to wait for the time we passed as an argument.&#xA;<h2 id="throttling-pattern">Throttling pattern</h2>&#xA;The throttling pattern sets a waiting time during which no more functions can be called again. Unlike the bounce pattern, the timeout is not reset if we try to call the function again.&#xA;<a href="images/throttling-eng.jpg" aria-label="Simplified diagram of the throttling pattern">&#xA;&#xA; <img class="md-image" width="1200" height="1200" loading="lazy" src="images/throttling-eng.jpg" alt="Simplified diagram of the throttling pattern"/>&#xA;&#xA;</a>&#xA;<h3 id="explanation-of-throttling-pattern">Explanation of throttling pattern</h3>&#xA;The code for throttling in javascript looks like this.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-javascript" data-lang="javascript">const throttling = (callback, delay) =&gt; {&#xA; let timeout&#xA; return (...args) =&gt; {&#xA; if (timeout !== undefined) {&#xA; return&#xA; }&#xA;&#xA; timeout = setTimeout(() =&gt; {&#xA; timeout = undefined&#xA; }, delay)&#xA;&#xA; return callback(...args)&#xA; }&#xA;}&#xA;</code></pre></div>The throttling function returns a function that will have two sides depending on the timeout status:&#xA;<ul>&#xA;<li>timeout is defined: this means that a function is already scheduled for execution, in this case the function does nothing, i.e. it blocks the execution of new functions by means of an empty return.</li>&#xA;<li>timeout is not defined: if timeout is not defined, we create a setTimeout and assign it to the timeout variable. This function, once its execution time has elapsed, will remove itself from the timeout variable. Subsequently, and to finish, we execute the callback function.</li>&#xA;</ul>&#xA;<h2 id="other-resources-on-debounce-and-throttling">Other resources on debounce and throttling</h2>&#xA;<ul>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://charliesbot.dev/blog/debounce-and-throttle" rel="noopener" target="_blank">Debounce and throttling in Typescript</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://webdesign.tutsplus.com/es/tutorials/javascript-debounce-and-throttle--cms-36783" rel="noopener" target="_blank">Debounce y throttling applied to the DOM</a>&#xA;</li>&#xA;</ul>&#xA;

Debounce and throttle are design patterns used to limit the execution of functions, generally they are used to restrict the amount of times an event is fired: click, scroll, resize or other events. Patterns are not exclusive to Javascript; in a previous post I explained how to use throttle to limit the number of requests received by the nginx server .&#xA;Both patterns generate a function that receives a callback and a timeout or delay.

Debounce and Throttle in Javascript

In this post I explain three methods to extend or customize Django&rsquo;s User model, without having to rewrite it from scratch, and keeping all &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/why-should-you-use-django-framework/">Django&rsquo;s user management features</a>&#xA;&#xA;But, before we start, let&rsquo;s see where Django&rsquo;s User model comes from.&#xA;<h2 id="where-does-the-django-user-model-come-from">Where does the Django User model come from?</h2>&#xA;Django&rsquo;s User model inherits from AbstractUser which, in turn, inherits from the AbstractBaseUser class.&#xA;<div class="mermaid">graph TD;&#xA; AbstractBaseUser-->AbstractUser;&#xA; AbstractUser-->User;&#xA;</div>&#xA; &#xA; &#xA; If you look at the Django source code, you will see that the User model you normally use has virtually no functionality of its own, but inherits all of its functionality from AbstractUser.&#xA;<a href="images/UserDjango.png" aria-label="Screenshot of Django User model code">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="985" height="201" loading="lazy" src="images/UserDjango.png" alt="Screenshot of Django User model code"/>&#xA; <figcaption>Screenshot of Django version 4.0 code</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;Now that we know the above, we can use the AbstractUser and AbstractBaseUser classes to create our custom User models.&#xA;<h2 id="inherit-from-subclass-abstractuser">Inherit from subclass AbstractUser</h2>&#xA;This method is probably the most popular method for extending Django&rsquo;s User model. This is because it retains almost all the functionality of the original User model.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python"># users/models.py&#xA;from django.contrib.auth.models import AbstractUser&#xA;from django.db import models&#xA;&#xA;class CustomUser(AbstractUser):&#xA; # Other properties defined by you&#xA; credits = models.PositiveIntegerField(verbose_name=&#39;credits&#39;,&#xA; default=0, &#xA; blank=True)&#xA;</code></pre></div>After creating a new class that inherits from AbstractUser, we need to tell Django that we want to use this new model instead of the default user model.&#xA;We set this behavior in our configuration file.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python"># settings.py&#xA;AUTH_USER_MODEL = &#39;users.CustomUser&#39;&#xA;</code></pre></div><h3 id="using-the-custom-model-in-djangos-account-views">Using the custom model in Django&rsquo;s account views</h3>&#xA;If we want to use the Django template system to automatically generate a registration form, we will need to tell Django to use the new user model, for this we inherit a new form from the UserCreationForm class, and pass it our custom model, which we can with the get_user_model method.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">from django.contrib.auth import get_user_model&#xA;from django.contrib.auth.forms import UserCreationForm&#xA;&#xA;User = get_user_model()&#xA;&#xA;class RegisterFormForCustomUser(UserCreationForm):&#xA; class Meta:&#xA; model = User&#xA; fields = [&#39;username&#39;, &#39;email&#39;]&#xA;</code></pre></div>And that&rsquo;s it, we can use it exactly as if we were using the User model included in Django.&#xA;<h3 id="django-admin-does-not-hashed-passwords">django admin does not hashed passwords</h3>&#xA;When we use a custom user model, we need to tell Django to handle passwords with the default user functionality&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">from django.contrib import admin&#xA;from django.contrib.auth.admin import UserAdmin&#xA;from django.contrib.auth import get_user_model&#xA;&#xA;user = get_user_model()&#xA;&#xA;class CustomUserAdmin(UserAdmin):&#xA; pass&#xA;&#xA;admin.site.register(user, CustomUserAdmin)&#xA;</code></pre></div>Now the admin panel will behave exactly as it would with the default Django user.&#xA;<h3 id="what-does-abstractuser-look-like-internally">What does AbstractUser look like internally?</h3>&#xA;Notice how the AbstractUser class inherits from _AbstractBaseUse_r and has multiple fields available to profile a user. Also, it cannot be instantiated directly, as it is an abstract class.&#xA;<a href="images/AbstractUserDjango-1.png" aria-label="Django AbstractUser class source code">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="1079" height="911" loading="lazy" src="images/AbstractUserDjango-1.png" alt="Django AbstractUser class source code"/>&#xA; <figcaption>Screenshot of Django version 4.0 AbstractUser code</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;Let&rsquo;s move on to the second method.&#xA;<h3 id="how-to-change-the-user-field-for-authentication">How to change the user field for authentication?</h3>&#xA;If you look at the code above, there is an uppercase property called USERNAME_FIELD, there you can specify another field to work as the user.&#xA;As you don&rsquo;t want two users to identify themselves in the same way that field has to be marked as unique. Besides that you have to modify the object manager, the code is a bit long so I won&rsquo;t put it here&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">class CustomUser(AbstractUser):&#xA; custom_id = models.CharField(max_length=40, unique=True)&#xA; # ...&#xA; USERNAME_FIELD = &#39;custom_id&#39;&#xA;</code></pre></div><h2 id="inherit-from-subclass-abstractbaseuser">Inherit from subclass AbstractBaseUser</h2>&#xA;This class, as you can see in the previous image, is the base class used to create the AbstractUser. Its operation is the minimum and it only has 3 fields:&#xA;<ul>&#xA;<li>password</li>&#xA;<li>last_login</li>&#xA;<li>is_active</li>&#xA;</ul>&#xA;It only has the authentication function. And you have to indicate which field will be used as username, to authenticate the user.&#xA;This method is usually used to fully customize the User model or when we need almost no extra fields.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python"># users/models.py&#xA;from django.contrib.auth.base_user import AbstractBaseUser&#xA;from django.db import models&#xA;&#xA;class CustomUser(AbstractBaseUser):&#xA; email = models.EmailField(verbose_name=&#39;emails&#39;, unique=True, max_length=255)&#xA; credits = models.PositiveIntegerField(verbose_name=&#39;credits&#39;,&#xA; default=0, &#xA; blank=True)&#xA; USERNAME_FIELD=&#39;email&#39;&#xA; REQUIRED_FIELDS = []&#xA;</code></pre></div>Remember to tell Django to use your custom model instead of the default one.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python"># settings.py&#xA;AUTH_USER_MODEL = &#39;users.CustomUser&#39;&#xA;</code></pre></div><h3 id="what-does-abstractbaseuser-look-like-internally">What does AbstractBaseUser look like internally?</h3>&#xA;The following image is a direct screenshot of the Django code in version 4.0&#xA;As you can see, it only has the 3 fields mentioned, it inherits directly from models.Model and its Meta class tells Python that it is an abstract model; you cannot create instances directly from it.&#xA;<a href="images/AbstractBaseUserDjango-1.png" aria-label="Django AbstractBaseUser class source code">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="1200" height="287" loading="lazy" src="images/AbstractBaseUserDjango-1.png" alt="Django AbstractBaseUser class source code"/>&#xA; <figcaption>Screenshot of Django AbstractBaseUser version 4.0</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;Now let&rsquo;s look at the third way to extend Django&rsquo;s User model.&#xA;<h2 id="create-a-profile-to-extend-the-model-user">Create a profile to extend the model User</h2>&#xA;Another way to extend the user model is to create another model that serves as a container for the extra fields and then relate it by an OneToOneField field to the model that the Django configuration receives by default.&#xA;This approach is ideal if we are the creator of a package that needs to customize the User model of the project to work, but without modifying it directly.&#xA;It is also useful when we need several types of users or different profiles, with different fields between them.&#xA;To create a profile in this way it is enough to declare a field that relates our new model to the User model, by means of an OneToOneField.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">from django.conf import settings&#xA;class Profile(models.Model):&#xA; # other fields&#xA; user = models.OneToOneField(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)&#xA;</code></pre></div>And to access our user, we access the field that relates it to the model we created.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">user = User.objects.get(username=&#39;user&#39;)&#xA;user.Profile&#xA;</code></pre></div><h2 id="other-resources">Other resources</h2>&#xA;<ul>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://github.com/django/django/tree/main/django/contrib/auth" rel="noopener" target="_blank">Original source code of the Django User model</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://docs.djangoproject.com/en/4.0/topics/auth/customizing/" rel="noopener" target="_blank">Django User model documentation</a>&#xA;</li>&#xA;</ul>&#xA;

In this post I explain three methods to extend or customize Django&rsquo;s User model, without having to rewrite it from scratch, and keeping all Django&rsquo;s user management features But, before we start, let&rsquo;s see where Django&rsquo;s User model comes from.&#xA;Where does the Django User model come from? Django&rsquo;s User model inherits from AbstractUser which, in turn, inherits from the AbstractBaseUser class.&#xA;graph TD; AbstractBaseUser-->AbstractUser; AbstractUser-->User; If you look at the Django source code, you will see that the User model you normally use has virtually no functionality of its own, but inherits all of its functionality from AbstractUser.

How to customize the User model in Django?

The select_related and prefetch_related methods are used to reduce the number of queries made to the database. This translates into response time for each view. In addition, using these methods is one of the actions to implement to improve the performance of a Django application select_related The select_related method is used to follow a relationship of type ForeignKey or OneToOneField to the respective objects it points to and obtain them..

Differences between select_related and prefetch_related in Django

When we use Typescript with React and we want to &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/types-for-react-components-with-children/">pass a children as prop to one of our components</a>&#xA;, we need to indicate the type. Generally we use the type React.FC, which is short for React.FunctionComponent. With this the Typescript message warning us of a children with type any will disappear.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-jsx" data-lang="jsx">const Component: React.FC = ({ children }) =&gt; {&#xA; return (&lt;div&gt;{children}&lt;/div&gt;)&#xA;}&#xA;</code></pre></div>In addition to allowing us to work with children, React.FC also causes an error if we try to return undefined from our component.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-jsx" data-lang="jsx">const Component: React.FC = ({ children }) =&gt; {&#xA; // Type &#39;() =&gt; undefined&#39; can&#39;t be assigned to type &#39;FC&lt;{}&gt;&#39;.&#xA; return undefined&#xA;}&#xA;&#xA;export default Component&#xA;</code></pre></div>As you can see, it is quite comfortable to use, but some people do not agree with its use.&#xA;<h2 id="reactfc-more-disadvantages-than-advantages">React.FC, more disadvantages than advantages?</h2>&#xA;What&rsquo;s the problem? Well, some developers claim that React.FC can bring more disadvantages than advantages, there is even a discussion on github (link at the end), in which it is debated whether it is convenient to remove one of the examples in the documentation that uses it.&#xA;The user who started this discussion believes that **the fact that React.FC is so popular is because its presence in the documentation positions it as the default way to handle React components with Typescript.&#xA;Here are some of the reasons why React.FC has more disadvantages than advantages.&#xA;<h3 id="reactfc-does-not-warn-us-about-unused-children">React.FC does not warn us about unused children</h3>&#xA;React.FC is not always the most explicit way to tell typescript that a component receives children as part of its props.&#xA;Imagine that we pass a children to the component, but we don&rsquo;t use it.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-jsx" data-lang="jsx">import Component from &#39;./Component&#39;;&#xA;&#xA;function App() {&#xA; return (&#xA; &lt;Component&gt;I&#39;m the children component&lt;/Component&gt;&#xA; );&#xA;}&#xA;&#xA;export default App;&#xA;</code></pre></div>Our component does receive the children as a prop, but the React.FC type appeases Typescript and prevents it from returning an error, even if we are not using it.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-jsx" data-lang="jsx">const Component: React.FC = () =&gt; {&#xA; return (&#xA; &lt;div&gt;I&#39;m not the children which receives the component&lt;/div&gt;&#xA; )&#xA;}&#xA;&#xA;export default Component&#xA;</code></pre></div>Or, for an opposite case; imagine that we do not want our component to receive a children as one of its props, however, as we are using React.FC we will not get any error.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-javascript" data-lang="javascript">import Component from &#39;./Component&#39;;&#xA;&#xA;function App() {&#xA; return (&#xA; &lt;Component&gt;&lt;div&gt;I shouldn&#39;t be here&lt;/div&gt;&lt;/Component&gt;&#xA; );&#xA;}&#xA;&#xA;export default App;&#xA;</code></pre></div><h3 id="subcomponent-pattern-in-react-gets-more-complicated">Subcomponent pattern in React gets more complicated</h3>&#xA;The &#xA;&#xA;<a class="markdown-link" href="https://medium.com/@kunukn_95852/react-components-with-namespace-f3d169feaf91" rel="noopener" target="_blank">component pattern as namespace</a>&#xA; is fairly simple to create without using React.FC, but with React.FC it can get quite complicated.&#xA;Don&rsquo;t know what it is? Think of a pattern that allows you to group components within a certain parent, which functions as a namespace for our child components; similar to how the C++ namespace std would work.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-jsx" data-lang="jsx">&lt;Namespace&gt;&#xA; &lt;Namespace.Component /&gt;&#xA;&lt;/Namespace&gt;&#xA;</code></pre></div>In its simplest form, omitting React.FC would look something like this:&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-jsx" data-lang="jsx">const Namespace = (props: NamespaceProps) =&gt; {/* ... */}&#xA;Namespace.Component = (props: ComponentProps) =&gt; { /*...*/ }&#xA;</code></pre></div>But if we choose to use React.FC the code would become more complicated and the readability would decrease a bit.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-jsx" data-lang="jsx">const Namespace: React.FC&lt;NamespaceProps&gt; &amp; { Component: React.FC&lt;ComponentProps&gt; } = (props) =&gt; {/* ... */ }&#xA;Namespace.Component = (props) =&gt; { /*...*/ }&#xA;</code></pre></div><h2 id="what-should-we-use-instead-of-reactfc">What should we use instead of React.FC?</h2>&#xA;The core of the criticism is that React.FC adds the children implicitly, going against the explicit nature of typescript.&#xA;However, the discussion I am talking about is just that, a discussion, it is not written in stone, you may consider that it is better to sacrifice a bit of readability in favor of convenience or, on the contrary, you may believe that it is important to be explicit when working with typescript.&#xA;If this is the case, consider that you can always declare the children as a prop explicitly, just as you would any other prop. And in the same way, you can declare the return value of your component as a JSX type element.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-jsx" data-lang="jsx">interface propsWithChildren {&#xA; children: React.ReactNode&#xA;}&#xA;&#xA;const Component = ({ children }: propsWithChildren): JSX.Element =&gt; {&#xA; return (&#xA; &lt;div&gt;{children}&lt;/div&gt;&#xA; )&#xA;}&#xA;&#xA;export default Component&#xA;</code></pre></div>Typescript should not warn you about any errors with this approach to the problem.&#xA;<h2 id="other-resources-on-the-subject">Other resources on the subject</h2>&#xA;Below are links to the original discussion and some posts on this topic.&#xA;<ul>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://github.com/facebook/create-react-app/pull/8177" rel="noopener" target="_blank">Eliminate React.FC from typescript template</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://medium.com/raccoons-group/why-you-probably-shouldnt-use-react-fc-to-type-your-react-components-37ca1243dd13" rel="noopener" target="_blank">Why you probably shouldn&rsquo;t use react fc to type your react components</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://www.harrymt.com/blog/2020/05/20/react-typescript-react-fc.html" rel="noopener" target="_blank">React Typescript&rsquo; React.FC</a>&#xA;</li>&#xA;</ul>&#xA;

When we use Typescript with React and we want to pass a children as prop to one of our components , we need to indicate the type. Generally we use the type React.FC, which is short for React.FunctionComponent. With this the Typescript message warning us of a children with type any will disappear.&#xA;const Component: React.FC = ({ children }) =&gt; { return (&lt;div&gt;{children}&lt;/div&gt;) } In addition to allowing us to work with children, React.

Why using React.FC could be a bad practice?

In addition to unit test testing and coverage measurement in go , this programming language is capable of profiling the efficiency of the code by analyzing it in a very detailed way. This is quite useful to find bottlenecks or very expensive parts of the code, which are called numerous times or whose performance can be improved.&#xA;How does Go profiling work internally in GNU/Linux? GNU/Linux, more specifically GNU, has an alarm signal called SIGPROF , this signal warns when a timer finishes measuring CPU usage and interrupts code execution.

Go: profiling or basic profiling of CPU usage

Go already has a testing module in its standard library that is ready for our use, we just need to import it and use it.&#xA;&#xA;&#xA;&#xA; <img width="60" height="60" src="https://res.cloudinary.com/dwrscezd2/image/upload/v1717959563/Go_gopher_favicon_uzxa20.svg" alt="">&#xA; <a target="_blank" rel=”nofollow” href="https://coffeebytes.dev/en/pages/go-programming-language-tutorial/">&#xA; Hey! did you know that I wrote a completely Free Go programming language tutorial?, you can find it directly in the top menu bar or clicking this box.</a>&#xA;&#xA;&#xA;<h2 id="testing-preparation-in-go">Testing preparation in go</h2>&#xA;For the tests to be carried out we need:&#xA;A file ending in _test.go * A file ending in _test.go * Run the command go test.&#xA;<ul>&#xA;<li>Run the go test command</li>&#xA;</ul>&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">├── go.mod&#xA;├── main.go&#xA;└── testing&#xA; ├── main.go&#xA; └── main_test.go&#xA;&#xA;1 directory, 5 files&#xA;</code></pre></div>Consider that, if you are going to &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-package-import-and-module-management/">assign a name to your package</a>&#xA;, you should never name it testing. Why? If you do, go will confuse its testing package with yours, returning those incorrect results.&#xA;To create the tests, inside the testing/main_test.go file, we need a function that receives as argument our testing package with the destructuring character.&#xA;We will compare the result using an if, or whatever we want and, if the test fails, we will call the Errorf method of the testing module.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">package main&#xA;&#xA;import &#34;testing&#34;&#xA;&#xA;func TestDivision(t *testing.T) {&#xA; total := Division(10, 2)&#xA; if total != 5 {&#xA; t.Errorf(&#34;División incorrecta, obtuvimos %d pero se esperaba %d&#34;, total, 5)&#xA; }&#xA;}&#xA;</code></pre></div>It is not necessary that the functions to be tested are inside the testing file, in this case I placed them inside testing/main.go.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">package main&#xA;&#xA;func Division(a int, b int) int {&#xA; return a / b&#xA;}&#xA;</code></pre></div><h2 id="execute-tests">Execute tests</h2>&#xA;To run the tests we need to find ourselves inside the directory where our files ending in _test.go are located and run the go test command. If the test passes we will get the PASS message.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">cd testing/&#xA;go test&#xA;&#xA;PASS&#xA;ok main/testing 0.001s&#xA;</code></pre></div>On the other hand, if the tests fail, the word FAIL will be printed on the screen:&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">--- FAIL: TestDivision (0.00s)&#xA; main_test.go:14: División incorrecta, obtuvimos 12 pero se esperaba 5&#xA;FAIL&#xA;exit status 1&#xA;FAIL main/testing 0.001s&#xA;</code></pre></div><h2 id="case-management-with-tables">Case management with tables</h2>&#xA;In the above example we used one function to test one case, however, if we needed to test multiple cases, we would need a function for each test, quite tedious, right?&#xA;To avoid filling up with functions, developers use an array composed of structs, where each struct represents a case to be tested. You can think of the array of structs as a table, where each row is a case and each column is a data type to be tested.&#xA;In this case, each struct in our array consists of three integers; the first two represent the arguments, while the last one is the result.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">tables := []struct {&#xA; &#x9;x int&#xA; &#x9;y int&#xA; &#x9;r int&#xA; }{&#xA; &#x9;{100, 10, 10}, // 100 / 10 = 10&#xA; &#x9;{200, 20, 10}, // 200 / 20 = 10&#xA; &#x9;{300, 30, 10},&#xA; &#x9;{1000, 100, 10},&#xA; }&#xA;</code></pre></div>I&rsquo;m sure you&rsquo;ve noticed that we&rsquo;re not covering division by zero, but leave it at that for now.&#xA;Now that we have our array of structs, we will iterate over each of its elements using &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-slices-y-arrays-characteristicas-and-basic-uses/">go&rsquo;s range function</a>&#xA;. This way we will cover each case.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">for _, table := range tables {&#xA; &#x9;total := Division(table.x, table.y)&#xA; &#x9;if total != table.r {&#xA; &#x9;&#x9;t.Errorf(&#34;División de %d entre %d incorrecta, obtuvimos: %d, pero el resultado es: %d.&#34;, table.x, table.y, total, table.r)&#xA; &#x9;}&#xA; }&#xA;</code></pre></div>If everything went well, we will pass all the tests.&#xA;<h2 id="coverage">Coverage</h2>&#xA;Coverage is already part of the code in go, so we do not need external libraries. If you don&rsquo;t know what Coverage is, think of it as the percentage of your code that is tested. If all your code goes through the tests you will have a coverage of 100%, if only half of it goes through the tests the coverage will be 50%. Previously I talked about coverage in my entry &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/unittest-python-are-python-tests-worthwhile/">unittest in Python</a>&#xA;&#xA;To calculate the coverage, simply add the -cover flag to the go test command.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">go test -cover&#xA;&#xA;PASS&#xA;coverage: 100.0% of statements&#xA;ok _/home/eduardo/Programacion/goTesting/testing 0.002s&#xA;</code></pre></div>As our function is tiny, we obtain a result of 100%, without breaking down, from coverage&#xA;<h3 id="export-coverage-results">Export coverage results</h3>&#xA;We can send all the raw data from our coverage test to an external file with the -coverprofile flag.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">go test -coverprofile=coverage.out&#xA;&#xA;mode: set&#xA;/home/eduardo/Programacion/goTesting/testing/main.go:3.33,5.2 1 1&#xA;</code></pre></div>This file, named coverage.out, which was generated, is a file containing raw data and will be needed to visualize the results in a more detailed way.&#xA;<h3 id="viewing-results-with-go-tool">Viewing results with go tool</h3>&#xA;To summarize in a more readable way the information of the file containing our coverage test, we will use the tool command, accompanied by the -func flag, followed by the file name. This will return a broken down coverage result.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">go tool cover -func=coverage.out&#xA;&#xA;/home/eduardo/Programacion/goTesting/testing/main.go:3: Division 100.0%&#xA;total: (statements) 100.0%&#xA;</code></pre></div>Go also allows us to visualize the coverage in HTML format, with colors, directly in our browser. For this we use the -html option, followed by the file with the coverage data.&#xA;When the command is executed, a browser tab will open and show the tested results in green and the untested results in red.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">go tool cover -html=coverage.out&#xA;</code></pre></div><a href="images/Captura-de-pantalla-de-2022-02-09-12-35-57.png" aria-label="Coverage en go">&#xA;&#xA; <img class="md-image" width="822" height="238" loading="lazy" src="images/Captura-de-pantalla-de-2022-02-09-12-35-57.png" alt="Coverage en go"/>&#xA;&#xA;</a>&#xA;Full html coverage in go&#xA;If we decide to modify our function to handle the division by zero cases, and run the coverage tests again, we will get a different scheme than before. Now a section of code not covered by the tests appears in red and our coverage dropped to 50%.&#xA;<a href="images/coverage-en-go.png" aria-label="Screenshot of coverage en go">&#xA;&#xA; <img class="md-image" width="1260" height="417" loading="lazy" src="images/coverage-en-go.png" alt="Screenshot of coverage en go"/>&#xA;&#xA;</a>&#xA;Incomplete html coverage in go&#xA;This is the end of this super short entry about go testing. For the next entry I will talk a little bit about profiling and I will finish the basic go entries to write again about Python.&#xA;<h2 id="other-resources-on-testing">Other resources on testing</h2>&#xA;<ul>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://blog.friendsofgo.tech/posts/empezando-con-los-tests-automatizados-en-go/" rel="noopener" target="_blank">Started with Friends of go automated tests</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://pkg.go.dev/testing" rel="noopener" target="_blank">Official Go documentation</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://github.com/stretchr/testify#assert-package" rel="noopener" target="_blank">Testify, to emulate Javascript testing syntax</a>&#xA;</li>&#xA;</ul>&#xA;

Go already has a testing module in its standard library that is ready for our use, we just need to import it and use it.&#xA;Hey! did you know that I wrote a completely Free Go programming language tutorial?, you can find it directly in the top menu bar or clicking this box. Testing preparation in go For the tests to be carried out we need:&#xA;A file ending in _test.

Go: basic testing and coverage

In past posts I talked a bit about goroutines, deadlocks and channels . But there is another quite interesting issue about goroutines that stands out when we use asynchrony and there are many functions accessing data at the same time and. Multiple functions reading and writing the same information can lead to chaotic situations where very strange things can happen.&#xA;Hey! did you know that I wrote a completely Free Go programming language tutorial?

Go: race conditions on goroutines and mutexes

When working with channels there is a quite common error that occurs when you are not familiar with the concepts, the error is &ldquo;fatal error: all goroutines are asleep - deadlock!&rdquo;, translated means something like &ldquo;fatal error: all goroutines are asleep - deadlocked&rdquo;. The first time I saw this error I was perplexed and, although I knew how to fix it, I didn&rsquo;t understand why it happened, so in this post I explain why it happens as I would have liked to have read it at the time.&#xA;&#xA;&#xA;&#xA; <img width="60" height="60" src="https://res.cloudinary.com/dwrscezd2/image/upload/v1717959563/Go_gopher_favicon_uzxa20.svg" alt="">&#xA; <a target="_blank" rel=”nofollow” href="https://coffeebytes.dev/en/pages/go-programming-language-tutorial/">&#xA; Hey! did you know that I wrote a completely Free Go programming language tutorial?, you can find it directly in the top menu bar or clicking this box.</a>&#xA;&#xA;&#xA;<h2 id="blocking-operations">Blocking operations</h2>&#xA;In go, operations that send or receive channel values are blocking inside their own goroutine (remember that the main function is a goroutine), i.e., they keep code execution waiting:&#xA;<ul>&#xA;<li>If an operation receives information from a channel, it will be blocked until it receives it.</li>&#xA;<li>If an operation sends information to a channel, it will be blocked until the sent information is received.</li>&#xA;</ul>&#xA;Knowing the two previous situations we will have two main cases:&#xA;<h3 id="blocking-or-deadlock-due-to-lack-of-sender">Blocking or deadlock due to lack of sender</h3>&#xA;What if an operation is waiting to receive information from a channel, but that channel is never going to send anything?&#xA;It happens when there is a channel that receives information, but not one that sends it.&#xA;<a href="images/deadlock-sender-go.jpg" aria-label="Deadlock due to lack of input channel">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="1200" height="1200" loading="lazy" src="images/deadlock-sender-go.jpg" alt="Deadlock due to lack of input channel"/>&#xA; <figcaption>There is no operation that sends data through a channel.</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">package main&#xA;&#xA;import (&#xA; &#34;fmt&#34;&#xA;)&#xA;&#xA;func main() {&#xA;&#xA; c := make(chan string)&#xA; fmt.Println(&lt;-c)&#xA;}&#xA;// fatal error: all goroutines are asleep - deadlock!&#xA;</code></pre></div><h3 id="blocking-or-deadlock-for-lack-of-recipient">Blocking or deadlock for lack of recipient</h3>&#xA;What if an operation sends information to a channel but there is no longer any other goroutine receiving information from that channel?&#xA;It happens when there is a channel that sends information, but not one that receives it.&#xA;<a href="images/deadlock-receiver-go.jpg" aria-label="Deadlock due to lack of output channel">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="1200" height="1200" loading="lazy" src="images/deadlock-receiver-go.jpg" alt="Deadlock due to lack of output channel"/>&#xA; <figcaption>In a deaclock due to lack of output channel there is no operation that receives text through a channel.</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">package main&#xA;&#xA;func main() {&#xA;&#xA; c := make(chan string)&#xA; c &lt;- &#34;text&#34;&#xA;}&#xA;// fatal error: all goroutines are asleep - deadlock!&#xA;</code></pre></div><h3 id="blocking-by-absence-of-goroutine">Blocking by absence of goroutine</h3>&#xA;There is a third case: if there is an operation that writes to and reads from a channel, as in the example below, but it is not inside another goroutine (different from the main goroutine) that reads the value, we will get a deadlock error.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">package main&#xA;&#xA;import &#34;fmt&#34;&#xA;&#xA;func main() {&#xA; var channel = make(chan string)&#xA; channel &lt;- &#34;forty two&#34;&#xA; fmt.Println(&lt;-channel) // This should be in other goroutine&#xA; fmt.Println(&#34;Finished&#34;)&#xA;}&#xA;// fatal error: all goroutines are asleep - deadlock!&#xA;</code></pre></div>In the three previous cases the program would be waiting and, as you know, it makes no sense to keep the program waiting for something that will never happen, so the execution is aborted and the fatal error &ldquo;fatal error: all goroutines are asleep - deadlock!&rdquo; is generated.&#xA;The above situation is referred to as a deadlock or deadlock.&#xA;<h2 id="deadlocks-or-dead-spots">Deadlocks or dead spots</h2>&#xA;In a deadlock there is a goroutine waiting to read or write to a channel, however there is no goroutine running because they are waiting for each other; they are in a deadlock from which no progress can be made.&#xA;<h3 id="prevent-deadlocks-on-go-with-goroutines">Prevent deadlocks on go with goroutines</h3>&#xA;In the &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-use-of-channels-to-communicate-goroutines/">introduction to channels in go post</a>&#xA;, I told you that the default capacity of a channel is 0, this causes that we cannot store data in the channels by default. If we try to store a data in a channel, we will get an error from the compiler, because there is no other goroutine to receive the value immediately.&#xA;To prevent a deadlock, we can immediately use the channel data by creating a goroutine that uses the channel value.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">package main&#xA;&#xA;import &#34;fmt&#34;&#xA;&#xA;func main() {&#xA; var channel = make(chan int)&#xA; go func(channel chan int) {&#xA; channel &lt;- 42&#xA; }(channel)&#xA; fmt.Println(&lt;-channel)&#xA; fmt.Println(&#34;Finished&#34;)&#xA;}&#xA;// No ocurre el error de deadlock&#xA;</code></pre></div>In this case I have created a goroutine with an anonymous function that reads from the channel.&#xA;<h3 id="how-to-prevent-deadlocks-in-go-using-buffered-channels">How to prevent deadlocks in go using buffered channels</h3>&#xA;If a channel does not have buffer, the value remains &ldquo;retained&rdquo; until it is received, blocking the execution while it happens, causing the deadlock or deadlock if no one receives it.&#xA;On the other hand, if the channel is buffered, then execution is blocked until the value has been copied to the buffer, so we will not get an error, even if no goroutine receives it.&#xA;<a href="images/deadlocks-prevencion-go-1.jpg" aria-label="Schematic of deadlock prevention in go">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="1200" height="1200" loading="lazy" src="images/deadlocks-prevencion-go-1.jpg" alt="Schematic of deadlock prevention in go"/>&#xA; <figcaption>In a buffered channel it does not matter if the value is not read because it has already been copied to the buffer.</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">package main&#xA;&#xA;import &#34;fmt&#34;&#xA;&#xA;func main() {&#xA; var channel = make(chan int, 1)&#xA; channel &lt;- 42&#xA; fmt.Println(&lt;-channel)&#xA; fmt.Println(&#34;Finished&#34;)&#xA;}&#xA;// No deadlock error&#xA;</code></pre></div><h2 id="resources-on-deadlocks-in-go">Resources on deadlocks in go</h2>&#xA;To conclude the article, I will share with you some interesting resources about deadlocks that I consider worth mentioning.&#xA;<ul>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://gist.github.com/YumaInaura/8d52e73dac7dc361745bf568c3c4ba37" rel="noopener" target="_blank">Golang - Understanding channel, buffer, blocks, deadlocks and gorotuines</a>&#xA;.</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://stackoverflow.com/questions/61759204/why-a-go-routine-block-on-channel-is-considered-as-deadlock" rel="noopener" target="_blank">Why a goroutine block on channel is considered as deadlock?</a>&#xA;.</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://go.dev/doc/effective_go#channels" rel="noopener" target="_blank">Effective go, channels</a>&#xA;</li>&#xA;</ul>&#xA;

When working with channels there is a quite common error that occurs when you are not familiar with the concepts, the error is &ldquo;fatal error: all goroutines are asleep - deadlock!&rdquo;, translated means something like &ldquo;fatal error: all goroutines are asleep - deadlocked&rdquo;. The first time I saw this error I was perplexed and, although I knew how to fix it, I didn&rsquo;t understand why it happened, so in this post I explain why it happens as I would have liked to have read it at the time.

Go: channels, understanding the goroutines deadlocks

So far I have explained how to run a goroutine, execute code concurrently with the goroutines and wait for them to finish executing but our goroutines can&rsquo;t do anything else, they can&rsquo;t cooperate with each other to speed up the processes.&#xA;Imagine you have a web scrapper that gets data from the internet concurrently; we get the data with goroutines and process it with goroutines. do we have to wait for all the goroutines to finish to use it? Ideally, the goroutines should communicate with each other the data and continue processing.&#xA;&#xA;&#xA;&#xA; <img width="60" height="60" src="https://res.cloudinary.com/dwrscezd2/image/upload/v1717959563/Go_gopher_favicon_uzxa20.svg" alt="">&#xA; <a target="_blank" rel=”nofollow” href="https://coffeebytes.dev/en/pages/go-programming-language-tutorial/">&#xA; Hey! did you know that I wrote a completely Free Go programming language tutorial?, you can find it directly in the top menu bar or clicking this box.</a>&#xA;&#xA;&#xA;<h2 id="communicating-goroutines-with-channels">Communicating goroutines with channels</h2>&#xA;Channels are &ldquo;conduits&rdquo; that accept a single type of data. Through these channels we &ldquo;introduce&rdquo; information that we can later &ldquo;take out&rdquo;.&#xA;The goroutines can send data to the channels and also read data from them, thus communicating with each other.&#xA;<a href="images/channels-en-go.jpg" aria-label="Schematic diagram of how a channel works in go">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="1200" height="800" loading="lazy" src="images/channels-en-go.jpg" alt="Schematic diagram of how a channel works in go"/>&#xA; <figcaption>Basic diagram of how channels work in Go</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;A channel in go is declared with make and the word chan, which refers to the word channel.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">c := make(chan string)&#xA;</code></pre></div>Channels are used to communicate goroutines, as in the &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/worker-pool-design-pattern-explanation/">worker-pool design pattern</a>&#xA;&#xA;<h3 id="channels-or-buffered-channels">Channels or buffered channels</h3>&#xA;The make function allows you to pass as an extra argument the limit amount of simultaneous data to be handled by that channel. **This is known as a buffered channel.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">c := make(chan string, 1)&#xA;</code></pre></div><h3 id="channels-or-unbuffered-channels">Channels or unbuffered channels</h3>&#xA;If we do not specify a buffer size the channel:&#xA;<ul>&#xA;<li>It will block the sender until the recipient is ready to receive the information.</li>&#xA;<li>Block the recipient until the sender is ready to send the information</li>&#xA;</ul>&#xA;Or to put it another way, if you try to send data to an unbuffered channel, the operation will block until the data is received. If you try to receive data it will block until the data is sent.&#xA;These channels are useful when you want to ensure that the sender and recipient are in sync and that the information is transmitted immediately, but they can lead to deadlocks if the sender and recipient are not in sync.&#xA;<h3 id="accessing-a-channel-in-a-function">Accessing a channel in a function</h3>&#xA;When we want to refer to the channel as an argument of a function, it is necessary to indicate the data type of the channel.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">func say(text string, c chan string) {}&#xA;</code></pre></div>The data type of a channel can also be one defined using a struct.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">func say(text string, c chan MiStruct) {}&#xA;</code></pre></div><h3 id="putting-data-into-a-channel">Putting data into a channel</h3>&#xA;To indicate data input through the channel, we use the character pair &lt;-&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">func say(text string, c chan string) {&#xA; c &lt;- text&#xA;}&#xA;</code></pre></div><h3 id="pulling-data-from-a-channel">Pulling data from a channel</h3>&#xA;To obtain the channel response we reverse the order between the channel and the &lt;- symbol.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">fmt.Println(&lt;-c)&#xA;</code></pre></div><h3 id="entering-and-retrieving-data-from-a-channel-in-go">Entering and retrieving data from a channel in go</h3>&#xA;The complete process of entering and extracting data from a channel in go would look something like this:&#xA;Create a channel of a data type using make.&#xA;2. We introduce a data (in this case string) to the channel using a&#xA;goroutine&#xA;3. Extract the text from the channel and use it (in this case just print it).&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">package main&#xA;&#xA;import &#34;fmt&#34;&#xA;&#xA;func escribirEnCanal(texto string, c chan string) {&#xA; c &lt;- texto&#xA;}&#xA;&#xA;func main() {&#xA; c := make(chan string)&#xA; go escribirEnCanal(&#34;Dato de un canal&#34;, c)&#xA; fmt.Println(&lt;-c)&#xA;}&#xA;</code></pre></div><h3 id="input-and-output-channels">Input and output channels</h3>&#xA;There are channels that receive information and channels that output information, by default a channel is bidirectional, but we can declare input and output channels.&#xA;To identify them, observe the flow of the arrow around the word chan; one enters (or goes to) chan and the other leaves chan.&#xA;This is an input channel.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">func say(text string, c chan&lt;- string) {}&#xA;</code></pre></div>While this is an output channel.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">func say(text string, c &lt;-chan string) {}&#xA;</code></pre></div>It is important to define the type of channel because, with bidirectional channels, we run the risk of causing a &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-channels-understanding-the-goroutines-deadlocks/">deadlock in our go program</a>&#xA;.&#xA;<h2 id="channel-capacity">Channel capacity</h2>&#xA;Remember I told you that the make function could set the maximum number of data a channel can work with? Well, it is possible to retrieve that information using the len function.&#xA;The len function tells us how much data there is in a channel, while cap returns the maximum capacity, respectively.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">c := make(chan string, 3)&#xA;c &lt;- &#34;dato1&#34;&#xA;c &lt;- &#34;dato2&#34;&#xA;fmt.Println(len(c), cap(c))&#xA;// 2 3&#xA;</code></pre></div>In the above example, the channel has two slots occupied, but has a total capacity of 3, even though not all of its slots are occupied.&#xA;<h2 id="close-a-channel-in-go">Close a channel in go</h2>&#xA;If we want to disable a channel, even if it has available capacity to store more data, the close function allows us to do so.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">c :=make(chan string, 3) &#xA;c &lt;- &#34;dato1&#34; &#xA;c &lt;- &#34;dato2&#34; &#xA;close(c)&#xA;c &lt;- &#34;dato3&#34;&#xA;//panic: send on closed channel&#xA;</code></pre></div><h2 id="iterate-on-a-channel">Iterate on a channel</h2>&#xA;Range is ideal for iterating over channel data. However, it is important to note that, there is no certainty about what data we will receive since the channel content can come from multiple goroutines.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">c := make(chan string, 3)&#xA;c &lt;- &#34;dato1&#34;&#xA;c &lt;- &#34;dato2&#34;&#xA;close(c)&#xA;for message := range c {&#xA; fmt.Println(message)&#xA;}&#xA;</code></pre></div>With that you know the basic information about the channels and how you can use them to communicate goroutines.&#xA;

So far I have explained how to run a goroutine, execute code concurrently with the goroutines and wait for them to finish executing but our goroutines can&rsquo;t do anything else, they can&rsquo;t cooperate with each other to speed up the processes.&#xA;Imagine you have a web scrapper that gets data from the internet concurrently; we get the data with goroutines and process it with goroutines. do we have to wait for all the goroutines to finish to use it?

Go: use of channels to communicate goroutines

As I mentioned in the introduction to the go programming language: &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-programming-language-introduction-to-variables-and-data-types/">go is a specialized concurrency language</a>&#xA;. It is a language that was designed to handle multiple tasks asynchronously. This entry is about go channels.&#xA;&#xA;&#xA;&#xA; <img width="60" height="60" src="https://res.cloudinary.com/dwrscezd2/image/upload/v1717959563/Go_gopher_favicon_uzxa20.svg" alt="">&#xA; <a target="_blank" rel=”nofollow” href="https://coffeebytes.dev/en/pages/go-programming-language-tutorial/">&#xA; Hey! did you know that I wrote a completely Free Go programming language tutorial?, you can find it directly in the top menu bar or clicking this box.</a>&#xA;&#xA;&#xA;<h2 id="concurrency-is-not-parallelism">Concurrency is not parallelism</h2>&#xA;Before we begin, remember that parallelism and concurrency are different. This post is too small to deal with such a broad topic, however there are two resources I want to highlight:&#xA;<ul>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="http://ferestrepoca.github.io/paradigmas-de-programacion/progconcurrente/concurrente_teoria/index.html" rel="noopener" target="_blank">Concurrent Programming by Felipe Restrepo Street</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://blog.thedojo.mx/2019/04/17/la-diferencia-entre-concurrencia-y-paralelismo.html" rel="noopener" target="_blank">Concurrency vs parallelism by Hector Patricio in The dojo blog</a>&#xA;</li>&#xA;</ul>&#xA;I quote a sentence from the first resource that, in my opinion, sums up the difference quite well:&#xA;<blockquote>&#xA;A program is concurrent if it can support two or more actions **in&#xA;progress.&#xA;A program is parallel if it can support two or more actions executing&#xA;simultaneously.&#xA;Felipe Restrepo Calle&#xA;</blockquote>&#xA;If they still seem confusing and you don&rsquo;t understand the difference, give those posts a read and you should be ready to move on.&#xA;<h2 id="coroutines-in-go">Coroutines in go</h2>&#xA;A &#xA;&#xA;<a class="markdown-link" href="https://en.wikipedia.org/wiki/Coroutine" rel="noopener nofollow" target="_blank">coroutine</a>&#xA;, in go, is a function or method that runs concurrently with other functions or methods. In go, corroutines are referred to as goroutines or goroutines. Even the main function, main, is executed inside one.&#xA;Goroutines are used in design patterns, such as the &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/worker-pool-design-pattern-explanation/">worker-pool-design-pattern</a>&#xA;&#xA;To generate a goroutine we add the keyword go before a function. This will schedule the function for asynchronous execution.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">func write(texto string) {&#xA;fmt.Println(texto)&#xA;}&#xA;fmt.Println(&#34;hey&#34;)&#xA;go write(&#34;hey again&#34;)&#xA;// hey&#xA;</code></pre></div>In the above case, due to its asynchronous nature, the goroutine does not stop code execution. This implies that the body of the main function continues its execution and **our goroutine never executes.&#xA;<a href="images/golang-goroutine-3.jpg" aria-label="Goroutine operation in go">&#xA;&#xA; <img class="md-image" width="1200" height="800" loading="lazy" src="images/golang-goroutine-3.jpg" alt="Goroutine operation in go"/>&#xA;&#xA;</a>&#xA;But then, how do we get our goroutine to run? The naive approach would be to use a sleep to pause the execution of the code. This, as you know, is nonsense, we can&rsquo;t be putting sleeps everywhere, the flow of the program would be unnecessarily slowed down!&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">// Don&#39;t&#xA;time.Sleep(1 * time.Second)&#xA;</code></pre></div>A better approach would be to create a WaitGroup.&#xA;<h2 id="waitgroups-in-go">WaitGroups in go</h2>&#xA;A WaitGroup will stop the execution of the program and wait for the goroutines to be executed.&#xA;Internally, a WaitGroup works with a counter, when the counter is at zero the execution of the code will continue, while if the counter is greater than zero, it will wait for the other goroutines to finish executing.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">var wg sync.WaitGroup&#xA;&#xA;wg.Wait()&#xA;fmt.Println(&#34;If waitgroup counter is greater than 0 it will continue the execution.&#34;)&#xA;</code></pre></div>And how do we change the counter value?&#xA;To increment and decrement the counter of the WaitGroup we will use the Add and Done methods, respectively.&#xA;<h3 id="the-add-method">The Add method</h3>&#xA;The Add method increments the WaitGroup counter by n units, where n is the argument we pass to it.&#xA;The trick is to call it every time you run a goroutine.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">wg.Add(1)&#xA;go write(&#34;Hey&#34;)&#xA;</code></pre></div><h3 id="the-done-method">The Done Method</h3>&#xA;The Done method is responsible for decrementing one unit of the WaitGroup counter. We will call it to tell the WaitGroup that the goroutine has finished and decrement the counter by one.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">func write(text string, wg *sync.WaitGroup) {&#xA; fmt.Println(text)&#xA; wg.Done()&#xA;}&#xA;</code></pre></div>Remember that the instance of the WaitGroup (wg *) needs to be passed by reference or else we will not access the original WaitGroup.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">func write(text string, wg *sync.WaitGroup) {&#xA; fmt.Println(text)&#xA; defer wg.Done()&#xA;}&#xA;</code></pre></div>Tip: use defer over the Done method to ensure that it is the last thing to be executed.&#xA;<a href="images/golang-goroutine-wait-2.jpg" aria-label="Operation of a waiting group in go">&#xA;&#xA; <img class="md-image" width="1200" height="800" loading="lazy" src="images/golang-goroutine-wait-2.jpg" alt="Operation of a waiting group in go"/>&#xA;&#xA;</a>&#xA;Once the wg.wait counter becomes zero, program execution continues.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">var wg sync.WaitGroup&#xA;wg.Add(1)&#xA;go writeInChannel(&#34;Hello&#34;, &amp;wg)&#xA;wg.Wait()&#xA;</code></pre></div><h3 id="anonymous-functions-in-goroutines">Anonymous functions in goroutines</h3>&#xA;When using goroutines, it is quite common to use anonymous functions to avoid declaring a new function.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">go func() {&#xA;}()&#xA;</code></pre></div>Remember that the parentheses that appear after the body of the function execute the anonymous function that we declare and also receive its arguments.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">go func(text string) {&#xA;}(&#34;Text&#34;)&#xA;</code></pre></div><h2 id="more-resources-about-goroutines">More resources about goroutines</h2>&#xA;Finally, here are some other resources on goroutines that you can consult.&#xA;<ul>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://golangbot.com/goroutines/" rel="noopener" target="_blank">Goroutines</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://www.youtube.com/watch?v=f6kdp27TYZs" rel="noopener" target="_blank">Goroutines by google devs</a>&#xA;</li>&#xA;</ul>&#xA;

As I mentioned in the introduction to the go programming language: go is a specialized concurrency language . It is a language that was designed to handle multiple tasks asynchronously. This entry is about go channels.&#xA;Hey! did you know that I wrote a completely Free Go programming language tutorial?, you can find it directly in the top menu bar or clicking this box. Concurrency is not parallelism Before we begin, remember that parallelism and concurrency are different.

Go: introduction to goroutines and concurrency

In go you can consider a package as all the files contained in a directory and a module as a collection of packages. To use the code of a package we need to import it, however, in Go there are no relative module imports. Before Go 1.8, to import packages (there were no modules) it was necessary to use the absolute path, considering as base the path pointed to by the environment variable $GOPATH or. Since Go 1.11, the easiest way to work with packages is to use go mod. I will explain the latter.&#xA;<a href="images/modulo-y-paquetes-en-go.png" aria-label="Differences between modules and packages in go">&#xA;&#xA; <img class="md-image" width="318" height="148" loading="lazy" src="images/modulo-y-paquetes-en-go.png" alt="Differences between modules and packages in go"/>&#xA;&#xA;</a>&#xA;Difference between modules and packages in go&#xA;<h3 id="defining-the-name-of-a-package-in-go">Defining the name of a package in Go</h3>&#xA;Before we start, do you remember that I told you in the &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-programming-language-introduction-to-variables-and-data-types/">introduction to the Go programming language</a>&#xA;, that the name of each package is set at the beginning of each file, placing it after the reserved word package?&#xA;For this example the package name will be videogame.&#xA;Once defined, I will create a model or struct in videogame.go.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">//videogame/videogame.go&#xA;package videogame&#xA;&#xA;type Videogame struct {&#xA; Id int32&#xA; Title string&#xA;}&#xA;</code></pre></div>Remember that the &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-structs-inheritance-polymorphism-and-encapsulation/">struct privacy rules</a>&#xA; say that in order for us to access a struct or its properties, from another package to where it was declared, we must use uppercase.&#xA;Once created, we will end up with a structure similar to this one&#xA;<a href="images/goModule.png" aria-label="Project file structure, a folder called videogame, with a file of the same name inside">&#xA;&#xA; <img class="md-image" width="310" height="112" loading="lazy" src="images/goModule.png" alt="Project file structure, a folder called videogame, with a file of the same name inside"/>&#xA;&#xA;</a>&#xA;Localization of the main file and our module in go&#xA;<h2 id="import-packages-with-gomod">Import packages with go.mod</h2>&#xA;<h3 id="what-is-a-gomod-file-for">What is a go.mod file for?</h3>&#xA;A go.mod file defines a module and allows us to set the directory that we will use as a base to import the packages.&#xA;<a href="images/goModFile.png" aria-label="go.mod file in the root of the project">&#xA;&#xA; <img class="md-image" width="320" height="214" loading="lazy" src="images/goModFile.png" alt="go.mod file in the root of the project"/>&#xA;&#xA;</a>&#xA;go.mod file containing the module name&#xA;In the above example the go.mod file will allow us to treat the videogame path as a package and import code from the mymodule/videogame path.&#xA;<h3 id="what-does-a-gomod-file-contain">What does a go.mod file contain?</h3>&#xA;The basic go.mod file is very short, it only specifies the name of the module, which we will use to perform the imports, and the version of go. That&rsquo;s all.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">module mymodule&#xA;&#xA;go 1.15&#xA;</code></pre></div><h3 id="create-a-gomod-file">Create a go.mod file</h3>&#xA;The go mod init command, followed by the name it will take as the base path for our package, will create a file named go.mod in the directory where we run it.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">go mod init mymodule&#xA;</code></pre></div>For example, if we name it mymodule, all the folders that are at the same level as the go.mod file and that declare a package at the beginning of their file, will be considered packages.&#xA;<a href="images/multiplesModulos.png" aria-label="Multiple directories to import as packages with go.mod">&#xA;&#xA; <img class="md-image" width="312" height="195" loading="lazy" src="images/multiplesModulos.png" alt="Multiple directories to import as packages with go.mod"/>&#xA;&#xA;</a>&#xA;And we can import them directly from our main.go file.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">import (&#xA; &#34;mymodule/foobar&#34;&#xA; &#34;mymodule/videogame&#34;&#xA;)&#xA;</code></pre></div><h2 id="remote-modules-in-go">Remote modules in Go</h2>&#xA;<h3 id="the-go-module-handler">The go module handler</h3>&#xA;Go has a module handler equivalent to pip and npm, python and javascript, respectively, called get.&#xA;<h3 id="go-get">go get</h3>&#xA;To get remote modules we run the go get command in console followed by the path to our package; it supports any repository, not just github. Since go version 1.18, go get does not compile the code it downloads, but just adds, updates or removes dependencies in the go.mod file.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">go get github.com/labstack/echo&#xA;</code></pre></div>After executing the command, go will download the files to the path pointed to by the $GOPATH environment variable and perform the corresponding imports into your go.mod file.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">module mypackage&#xA;&#xA;go 1.15&#xA;&#xA;require (&#xA; github.com/labstack/echo v3.3.10+incompatible // indirect&#xA; github.com/labstack/gommon v0.3.1 // indirect&#xA;)&#xA;</code></pre></div>You will notice that their packages will be available for us to import with their respective path.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">import &#34;github.com/labstack/echo&#34;&#xA;</code></pre></div>In case we need a specific version we declare it after the route.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">go get github.com/labstack/echo/v4&#xA;</code></pre></div><h3 id="go-install">go install</h3>&#xA;On the other hand, go install does not download code, but compiles a module and installs the binary into $GOPATH/bin, ignoring the contents of the go.mod file when a version is specified to it via the command line.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">go install sigs.k8s.io/kind@v0.9.0&#xA;</code></pre></div>Go install will generally be used to install commands.&#xA;<h3 id="import-remote-packages-in-go">Import remote packages in go</h3>&#xA;Packages found in code repositories, such as GitHub, GitLab or BitBucket, require that we specify the full path to the repository as their import path.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">go mod init github.com/user/package&#xA;</code></pre></div><h2 id="import-packages-without-using-them">Import packages without using them</h2>&#xA;There are times when we may want to import packages and not use them. For this, just add an underscore before the import.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">import (&#xA; _ &#34;fmt&#34;&#xA;)&#xA;</code></pre></div><h2 id="aliases-when-importing-packages">Aliases when importing packages</h2>&#xA;Go also allows us to declare an alias when importing a package by prefixing the alias to the import path.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">import ourAlias &#34;route/to/package&#34;&#xA;</code></pre></div>That way we can treat our alias as if it were the name of the package we are importing.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">import ourAlias &#34;mypackage/videogame&#34;&#xA;// ... our alias replaces videogame&#xA;var vd = ourAlias.Videogame{Id: 1, Title: &#34;hello&#34;}&#xA;</code></pre></div><h3 id="imports-with-dot">Imports with dot</h3>&#xA;Go allows direct access to the contents of the package if we import using a dot as alias. In this way we can ignore the package name and directly access the objects it contains.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">import . &#34;mypackage/videogame&#34;&#xA;// ... we can replace videogame.Videogame by Videogame&#xA;var vd = Videogame{Id: 1, Title: &#34;hello&#34;}&#xA;</code></pre></div><h2 id="bookstores-in-go">Bookstores in Go</h2>&#xA;If you are looking for libraries to speed up the development of a project, there is a directory of frameworks, libraries and utilities at &#xA;&#xA;<a class="markdown-link" href="http://awesome-go.com/" rel="noopener" target="_blank">Awesome go</a>&#xA;, there are resources for everything from GUI, ORMs, web frameworks, machine learning and everything you can imagine.&#xA;<h2 id="other-resources">Other resources</h2>&#xA;<ul>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://www.digitalocean.com/community/tutorials/understanding-the-gopath-es" rel="noopener" target="_blank">Sobre la variable $GOPATH y su configuración</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://scene-si.org/2018/01/25/go-tips-and-tricks-almost-everything-about-imports/" rel="noopener" target="_blank">Sobre imports (en inglés)</a>&#xA;</li>&#xA;</ul>&#xA;

In go you can consider a package as all the files contained in a directory and a module as a collection of packages. To use the code of a package we need to import it, however, in Go there are no relative module imports. Before Go 1.8, to import packages (there were no modules) it was necessary to use the absolute path, considering as base the path pointed to by the environment variable $GOPATH or.

Go: package import and module management

As I already mentioned to you in the introduction to the Golang or Go programming language , this language does not have a reserved word for dealing with classes, but uses structs to emulate features such as inheritance, polymorphism, encapsulation and other properties of classes that you have probably used in other programming languages.&#xA;Hey! did you know that I wrote a completely Free Go programming language tutorial?, you can find it directly in the top menu bar or clicking this box.

Go: Structs, inheritance, polymorphism and encapsulation

In this entry I will explain the basics of how strings, runes and bytes work in go, and even a little bit of utf-8.&#xA;To explain the topic I will assume you know the basics of slices and data types in go, if you don&rsquo;t know about these topics visit my array, slices in golang entry.&#xA;Hey! did you know that I wrote a completely Free Go programming language tutorial?, you can find it directly in the top menu bar or clicking this box.

Go: string runes and bytes explained

In the go programming language, a map or hash table is the equivalent of a dictionary; they have a key that is related to a value. The key and value can be of different data types, but all keys must be of a single type and all values must be of the same type.&#xA;&#xA;&#xA;&#xA; <img width="60" height="60" src="https://res.cloudinary.com/dwrscezd2/image/upload/v1717959563/Go_gopher_favicon_uzxa20.svg" alt="">&#xA; <a target="_blank" rel=”nofollow” href="https://coffeebytes.dev/en/pages/go-programming-language-tutorial/">&#xA; Hey! did you know that I wrote a completely Free Go programming language tutorial?, you can find it directly in the top menu bar or clicking this box.</a>&#xA;&#xA;&#xA;Together with the &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-slices-y-arrays-characteristicas-and-basic-uses/">array and the go slice</a>&#xA;, golang maps are structures that serve as a collection of values.&#xA;<h2 id="inner-workings-of-golang-maps">Inner workings of golang maps</h2>&#xA;In go a map works quite similar to any other language. In go there are buckets, a type of section consisting of 8 key-value pairs. The hash function receives the key and redirects us to the appropriate bucket, that is, the space of 9 key-value pairs where our key is located and, once there, it looks for the correct key.&#xA;<a href="images/mapsGolang-1.png" aria-label="Inner workings of golang maps in the programming language go.">&#xA;&#xA; <img class="md-image" width="800" height="800" loading="lazy" src="images/mapsGolang-1.png" alt="Inner workings of golang maps in the programming language go."/>&#xA;&#xA;</a>&#xA;Internal operation of golang maps. The information is taken from the &#xA;&#xA;<a class="markdown-link" href="https://go.dev/src/runtime/map.go" rel="noopener" target="_blank">official documentation of a map</a>&#xA;.&#xA;To declare a map, we use the word map and enclose the data type of the key in square brackets, followed by the data type of the value.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">var dictionary map[string]int&#xA;//A map with key of string type and values of int type &#xA;dictionary[&#34;hello&#34;] = 0&#xA;dictionary[&#34;panic&#34;] = 1&#xA;fmt.Println(dictionary)&#xA;// panic: assignment to entry in nil map&#xA;</code></pre></div>However, if we execute the previous thing it will give us an error. Why? It is important that you know that golang maps are references, they point to a memory location, as we create an empty map it points to nothing, to nil, so if we try to modify it, it will give us an error.&#xA;As with the slice, we have two ways to create a map or dictionary.&#xA;<ul>&#xA;<li>Passing values after the data type of the value</li>&#xA;<li>Using the make function.</li>&#xA;</ul>&#xA;<h3 id="create-a-map-in-go-with-values">Create a map in go with values</h3>&#xA;We can create a map or dictionary using map, the data type of the braces in square brackets, followed by the data type of the values and then the data key value in square brackets, separating each one with a colon.&#xA;The map keys can be modified and even new ones can be added.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">var account = map[string]int{&#xA; &#34;Anna&#34;: 100,&#xA; &#34;Renee&#34;: 200,&#xA; &#34;Kakuro&#34;: 300,&#xA; &#34;Joy&#34;: 400,&#xA;}&#xA;account[&#34;Anna&#34;] = 500&#xA;account[&#34;Colombe&#34;] = 900&#xA;</code></pre></div>We can also let go infer that it is a map, but only within a function, using the walrus operator &ldquo;:=&rdquo;.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">account := map[string]int{&#xA; &#34;Anna&#34;: 100,&#xA; &#34;Renee&#34;: 200,&#xA; &#34;Kakuro&#34;: 300,&#xA; &#34;Joy&#34;: 400,&#xA;}&#xA;account[&#34;Anna&#34;] = 500&#xA;account[&#34;Colombe&#34;] = 900&#xA;</code></pre></div><h3 id="create-a-map-in-go-with-make">Create a map in go with make</h3>&#xA;To create a map by allocating memory we need to use the make function and specify the type of data that the keys and values will have after the word map.&#xA;In this case we do not have to pass the map length argument to make. If we omit the map size, internally, go will assign a small value to it.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">var dictionary = make(map[string]int)&#xA;dictionary[&#34;hello&#34;] = 2&#xA;dictionary[&#34;world&#34;] = 1&#xA;fmt.Println(dictionary)&#xA;// map[hello:2 world:1]&#xA;</code></pre></div>Now watch this! We have a map or dictionary with only two keys, see what happens if we access a third one.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">fmt.Println(balance[&#34;user&#34;])&#xA;// 0&#xA;// How can we distinguish between a zero balance or a user that doesn&#39;t exist&#xA;</code></pre></div>If we try to access a key that does not exist, go will return its respective zero value, but this leads us to a problem: how do we distinguish whether we have a zero because the key does not exist or because the value of our key is zero?&#xA;<h3 id="distinguish-between-non-existent-and-zero-values">Distinguish between non-existent and zero values</h3>&#xA;To distinguish between a zero value, go provides a second return value, which indicates whether a key exists. This second value is a boolean: true or false.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">value, exist := dictionary[&#34;NonExistent&#34;]&#xA;</code></pre></div><h3 id="optional-capacity-in-golang-maps">Optional capacity in golang maps</h3>&#xA;To set a maximum key capacity in a map, we pass the length of the map as the second argument.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">m := make(map[string]int,99)&#xA;</code></pre></div>However, unlike slices, this length only tells the compiler to allocate a minimum amount of memory; if we add more keys than the maximum value, they will still be added, although not as efficiently.&#xA;<h3 id="delete-keys-with-delete">Delete keys with delete</h3>&#xA;If we want to get rid of a key from our map, we use the delete, function, which deletes a key from a map or dictionary.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">delete(dictionary, &#34;hello&#34;)&#xA;</code></pre></div><h2 id="traverse-golang-maps-with-range">Traverse golang maps with range</h2>&#xA;Just as with an array or a slice, we can tour a map using range. Each iteration will return the key and value.&#xA;Remember that, being a map, the elements will be returned in no particular order.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">for key, value := range dictionary {&#xA; fmt.Println(key,value)&#xA; }&#xA;</code></pre></div>This is the minimum you should know about golang maps or dictionaries.&#xA;

In the go programming language, a map or hash table is the equivalent of a dictionary; they have a key that is related to a value. The key and value can be of different data types, but all keys must be of a single type and all values must be of the same type.&#xA;Hey! did you know that I wrote a completely Free Go programming language tutorial?, you can find it directly in the top menu bar or clicking this box.

Golang maps or dictionaries

In go or golang slices, arrays and &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-maps-o-dictionaries/">maps</a>&#xA; are structures for handling data collections. In this entry I am going to talk about the first two: slices and arrays.&#xA;In this entry I am going to use data types, zero values, and other very basic aspects of go. If you don&rsquo;t know what I&rsquo;m talking about, visit my entry &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-programming-language-introduction-to-variables-and-data-types/">Golang: introduction to the language, variables and data types</a>&#xA;.&#xA;&#xA;&#xA;&#xA; <img width="60" height="60" src="https://res.cloudinary.com/dwrscezd2/image/upload/v1717959563/Go_gopher_favicon_uzxa20.svg" alt="">&#xA; <a target="_blank" rel=”nofollow” href="https://coffeebytes.dev/en/pages/go-programming-language-tutorial/">&#xA; Hey! did you know that I wrote a completely Free Go programming language tutorial?, you can find it directly in the top menu bar or clicking this box.</a>&#xA;&#xA;&#xA;<h2 id="arrays-in-go">Arrays in go</h2>&#xA;Arrays are immutable data collections, to create an array we need to define its size and the type of data it will contain, once declared it cannot be modified.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">var array [4]int&#xA;</code></pre></div>In the above example, we have an array with space for 4 integers. The values that we do not assign will be assigned as zero values.&#xA;<a href="images/arrayGolang-1.png" aria-label="Structure of an array in go">&#xA;&#xA; <img class="md-image" width="800" height="200" loading="lazy" src="images/arrayGolang-1.png" alt="Structure of an array in go"/>&#xA;&#xA;</a>&#xA;<h3 id="assign-values-to-an-array">Assign values to an array</h3>&#xA;To assign values to an array, previously declared, we use its index.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">array[1] = 1&#xA;// [0, 1, 0, 0]&#xA;</code></pre></div>We can also create an array directly inside a function by placing each element of the array between braces, separated by commas.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">array := [4]int{0, 0, 0, 0}&#xA;</code></pre></div><h2 id="slices-in-go">Slices in go</h2>&#xA;Slices are mutable collections of data types. Internally it is an abstraction of an array, with a difference, they can be modified.&#xA;However, when declaring a slice, and then trying to modify one of its indexes, just as we would do with an array, we will have an error. Why? Because a slice is a reference, and when it is created empty, we are pointing to nothing, to nil.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">var slice []int&#xA;slice[0] = 1&#xA;// panic: runtime error: index out of range [0] with length 0&#xA;</code></pre></div>Internally a slice is a struct with a pointer to the real array. In addition to the pointer, it has a property called cap and len, which refer to the capacity and length of the array, respectively.&#xA;<a href="images/sliceGolang.png" aria-label="Structure of a slice in go">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="800" height="200" loading="lazy" src="images/sliceGolang.png" alt="Structure of a slice in go"/>&#xA; <figcaption>A slice pointer points to the data it contains</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;To create a non-empty slice we have two ways to do it:&#xA;<ul>&#xA;<li>Allocate memory with the make function.</li>&#xA;<li>Declare it directly by passing the content after the slice data type.</li>&#xA;</ul>&#xA;<h3 id="create-a-slice-with-make">Create a slice with make</h3>&#xA;The make function allocates memory and initializes an object of type slice, map or chan and returns it. If we use make, it is necessary to pass the length of the slice as a second argument.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">var slice = make([]int, 4)&#xA;slice[0] = 1&#xA;fmt.Println(slice)&#xA;// [1,0,0,0]&#xA;</code></pre></div>If we try to add an element beyond the capacity we defined we will get an error.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">slice[4] = 4&#xA;// panic: runtime error: index out of range [4] with length 4&#xA;</code></pre></div>For more details &#xA;&#xA;<a class="markdown-link" href="https://pkg.go.dev/builtin#make" rel="noopener" target="_blank">check the documentation of the make function</a>&#xA;.&#xA;<h3 id="creating-slices-with-values">Creating slices with values</h3>&#xA;We can create a slice in a single step, passing the content directly to it, placing the elements of the slice between braces, separated by commas.&#xA;Notice how we do not specify the size of the slice.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">var slice = []int{0, 1, 2, 3, 4}&#xA;</code></pre></div>It is also possible to let go automatically detect that it is a slice using the walrus operator &ldquo;:=&rdquo;. Only possible within a function&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">slice := []int{0, 1, 2, 3, 4}&#xA;</code></pre></div><h3 id="partitioning-slices">Partitioning slices</h3>&#xA;The slices can be split in a Python-like style, specifying an inclusive position for the first digit and exclusive for the second digit.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">slice[2:] // {2, 3, 4}&#xA;slice[:2] // {0, 1}&#xA;slice[2:3]// { 2 }&#xA;</code></pre></div>If we do not specify one of the two, it will take the first position for the first digit and the last position for the second digit.&#xA;<h3 id="extending-a-slice">Extending a slice</h3>&#xA;Slices are mutable, they can be extended using the append function, which receives any number of elements, separated by commas.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">sliceExtendido := append(slice, 5)&#xA;// [1 2 3 4 6 5]&#xA;otroSliceExtendido := append(sliceExtendido, 6, 7, 8)&#xA;// [1 2 3 4 6 5 6 7 8]&#xA;</code></pre></div>It is possible to create a new slice from the destructuring of a slice. The destructuring is carried out by putting three dots (&hellip;) at the end of the slice.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">nuevoSlice :=[]int{9, 10}&#xA;// [8 9]&#xA;sliceHastaDiez = append(nuevoSlice, otroSliceExtendido...)&#xA;// [1 2 3 4 6 5 6 7 8 9 10]&#xA;</code></pre></div><h2 id="traverse-array-and-slices-with-range">Traverse array and slices with range</h2>&#xA;Similar to Python syntax, we can traverse an array, a slice or a map (I&rsquo;ll talk about maps in the next post) using range. Each iteration will return the index and element of the array or slice, or the key and value in the case of maps.&#xA;Here we iterate over an array, notice how we are declaring the size beforehand.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">var array [2]string&#xA; array[0] = &#34;Nier&#34;&#xA; array[1] = &#34;Hollow knight&#34;&#xA; for index, videojuego := range array {&#xA; &#x9;fmt.Println(index, videojuego)&#xA; }&#xA;</code></pre></div>In the case of a slice, notice how we do not specify a size between the square brackets.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">list := []int{0, 1, 2, 3, 4, 5}&#xA; for i, n := range list {&#xA; &#x9;fmt.Println(i, n)&#xA; }&#xA;</code></pre></div><h2 id="how-to-convert-an-array-into-an-slice-in-go">How to convert an array into an slice in Go?</h2>&#xA;To convert an array into a slice in Go, we can use the following syntax [:]&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">newArray := mySlice[:]&#xA;</code></pre></div>And that&rsquo;s the basics of slices and arrays, for the next post I&rsquo;m going to talk about maps in go.&#xA;

In go or golang slices, arrays and maps are structures for handling data collections. In this entry I am going to talk about the first two: slices and arrays.&#xA;In this entry I am going to use data types, zero values, and other very basic aspects of go. If you don&rsquo;t know what I&rsquo;m talking about, visit my entry Golang: introduction to the language, variables and data types .&#xA;Hey! did you know that I wrote a completely Free Go programming language tutorial?

Go: slices and arrays, basic characteristics and most common uses

This entry will deal with loops in the go programming language.&#xA;&#xA;&#xA;&#xA; <img width="60" height="60" src="https://res.cloudinary.com/dwrscezd2/image/upload/v1717959563/Go_gopher_favicon_uzxa20.svg" alt="">&#xA; <a target="_blank" rel=”nofollow” href="https://coffeebytes.dev/en/pages/go-programming-language-tutorial/">&#xA; Hey! did you know that I wrote a completely Free Go programming language tutorial?, you can find it directly in the top menu bar or clicking this box.</a>&#xA;&#xA;&#xA;Go handles loops a little differently than what you are used to. If you&rsquo;re already fluent in any other programming language, you probably remember while, do while and for loops. And if you come from Python or Javascript, you&rsquo;ll remember how useful for x in or for x of loops are.&#xA;Well, as there are more than enough loops for. Yes, there is no while or do while. But then how do I use the rest of the loops? Read on and I&rsquo;ll explain.&#xA;If you don&rsquo;t know anything about Go and want to start with the basics visit my entry &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/go-programming-language-introduction-to-variables-and-data-types/">Golang: introduction, variables and data types</a>&#xA;.&#xA;If you currently use Python and want to see how it is different from Go, visit my &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/python-vs-go-go-which-is-the-best-programming-language/">python vs go</a>&#xA; post.&#xA;<h2 id="if-and-else">If and else</h2>&#xA;If_ and else allow you to execute blocks of code conditionally and keep the same syntax as in almost all languages.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">if true {&#xA; fmt.Println(&#34;Verdadero&#34;)&#xA;} else {&#xA; fmt.Println(&#34;Falso&#34;)&#xA;}&#xA;</code></pre></div><h3 id="else-if">else if</h3>&#xA;And of course go also has an else if.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">edad := 18&#xA;if edad &lt; 18 {&#xA; fmt.Println(&#34;Menor de edad&#34;)&#xA;} else if edad &gt; 18 {&#xA; fmt.Println(&#34;Mayor de edad&#34;)&#xA;} else {&#xA; fmt.Println(&#34;Tiene 18 exactamente&#34;)&#xA;}&#xA;</code></pre></div><h2 id="loops-for-in-go">Loops for in go</h2>&#xA;In go there are several types of for loops: counter, conditional, range and infinite.&#xA;<h3 id="loops-with-counter">Loops with counter</h3>&#xA;This is the classic loop that you already know from Javascript, C++, etc. In which you declare a variable, specify a condition, and make changes to the variable.&#xA;We declare &ldquo;i&rdquo; equal to 0, as long as &ldquo;i&rdquo; is less than 10, it executes the next block and subsequently increments &ldquo;i&rdquo; by one, each instruction separated by a semicolon.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">for i:= 0; i &lt; 10; i++ {&#xA; // ...&#xA;}&#xA;</code></pre></div><h3 id="loop-with-conditional">Loop with conditional</h3>&#xA;In this type of loop a condition is evaluated, if the result is true, the block is executed, if not, that block of code is skipped. This type of for loop would be the equivalent of the while loop.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">counter := 0&#xA;for counter &lt; 10 {&#xA; counter ++&#xA;}&#xA;</code></pre></div><h3 id="loop-with-range">Loop with range</h3>&#xA;Range allows us to traverse an iterable structure from beginning to end and allows us to access the respective index and element. It is ideal for traversing arrays, strings, slices, maps, channels and any structure that can be traversed.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">HolaMundo := &#34;Hola mundo&#34;&#xA; for index, letra := range HolaMundo {&#xA; &#x9;fmt.Printf(&#34;%d %c \n&#34;, index, letra)&#xA; }&#xA;/*&#xA;0 H &#xA;1 o &#xA;2 l &#xA;3 a &#xA;4 &#xA;5 m &#xA;6 u &#xA;7 n &#xA;8 d &#xA;9 o*/&#xA;</code></pre></div><h3 id="infinite-loop">Infinite loop</h3>&#xA;A for loop without condition will run forever.&#xA;The only way to get out of an infinite for loop is with a break.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">counterForever := 0&#xA;for {&#xA; counterForever++&#xA;}&#xA;</code></pre></div><h2 id="break">break</h2>&#xA;As I just mentioned, break breaks a loop and continues code execution.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">counterForever := 0&#xA;for {&#xA; counterForever++&#xA; fmt.Println(counterForever)&#xA; if counterForever &gt; 5 {&#xA; fmt.Println(&#34;Aquí se rompe el bucle&#34;)&#xA; break&#xA;}&#xA;}&#xA;// 1&#xA;// 2&#xA;// 3&#xA;// 4&#xA;// 5&#xA;// 6&#xA;// Aquí se rompe el bucle&#xA;</code></pre></div><h3 id="break-in-loops-with-name-in-go">Break in loops with name in go</h3>&#xA;In other programming languages, such as Python, break would break the immediate loop, i.e. the immediate loop it is in. Wouldn&rsquo;t it be great to be able to stop the outer loop from the inner loop? In go it is possible in a simple way&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">while True:&#xA; while True:&#xA; break&#xA; print(&#34;El bucle principal continua ejecutándose&#34;)&#xA;# El bucle principal continua ejecutándose&#xA;# El bucle principal continua ejecutándose&#xA;# El bucle principal continua ejecutándose&#xA;</code></pre></div>Go allows us to assign names to the loops, what for? To reference specific loops and be able to break them using break. Take a look at this example:&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">loop:&#xA; for {&#xA; &#x9;for {&#xA; &#x9;&#x9;fmt.Println(&#34;Rompiendo el bucle externo&#34;)&#xA; &#x9;&#x9;break loop&#xA; &#x9;}&#xA; &#x9;fmt.Println(&#34;Esto nunca se imprimirá en pantalla&#34;)&#xA; }&#xA;</code></pre></div>We name our loop as loop and now we execute an infinite loop that will have an infinite loop inside it. This last loop will break the outer loop, named loop, so the second statement will never be printed on the screen.&#xA;<h2 id="continue">continue</h2>&#xA;Continue stops the current iteration of the loop and continues its execution in the next iteration.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">counter := 0&#xA;for counter &lt; 10 {&#xA; counter ++&#xA; if counter == 3 {&#xA; fmt.Println(&#34;Nos brincamos el 3&#34;)&#xA; continue&#xA; }&#xA; fmt.Println(counter)&#xA;}&#xA;//1&#xA;//2&#xA;//Nos brincamos el 3&#xA;//4&#xA;</code></pre></div><h2 id="defer">defer</h2>&#xA;Defer delays the execution of a line of code until the end of the code. It is quite similar to what the defer attribute with HTML script tag does.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">defer fmt.Println(&#34;Esto se va a ejecutar hasta el final&#34;)&#xA; fmt.Println(&#34;Esto se va a ejecutar primero&#34;)&#xA; fmt.Println(&#34;Esto se va a ejecutar después&#34;)&#xA;// Esto se va a ejecutar primero&#xA;// Esto se va a ejecutar después&#xA;// Y esto se va a ejecutar hasta el final&#xA;</code></pre></div>What&rsquo;s the point? Well, it is ideal to close connections to databases, files or to make some type of cleaning to the objects of our code.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go">const conexionBaseDeDatos := abreBaseDeDatos()&#xA;defer cierraBaseDeDatos()&#xA;queryBaseDeDatos()&#xA;otraQuery()&#xA;</code></pre></div>For the next Go entry I&rsquo;m going to talk about the basics of slices, arrays and maps.&#xA;Remember that you can visit the &#xA;&#xA;<a class="markdown-link" href="https://go.dev/doc/" rel="noopener" target="_blank">official go documentation</a>&#xA; if there is anything you want to learn more about.&#xA;

This entry will deal with loops in the go programming language.&#xA;Hey! did you know that I wrote a completely Free Go programming language tutorial?, you can find it directly in the top menu bar or clicking this box. Go handles loops a little differently than what you are used to. If you&rsquo;re already fluent in any other programming language, you probably remember while, do while and for loops. And if you come from Python or Javascript, you&rsquo;ll remember how useful for x in or for x of loops are.

Go: loops for, break, continue, defer, if and else

This entry will discuss the basic syntax of Go functions. If you know absolutely nothing about go visit my entry go: introduction to programming language, variables and data types to start from the beginning of this tutorial series.&#xA;Hey! did you know that I wrote a completely Free Go programming language tutorial?, you can find it directly in the top menu bar or clicking this box. Now, let&rsquo;s move on to the functions.

Go: functions, arguments and the fmt package

Golang, also known as go, is a compiled programming language developed by Google. It is a language quite appreciated according to the latest Stackoverflow surveys (2023), as you can see in my python vs go post, where I also compare the good, the bad and the ugly of this language.&#xA;Hey! did you know that I wrote a completely Free Go programming language tutorial?, you can find it directly in the top menu bar or clicking this box.

Go, coding language, introduction to variables and data types

Channel layers allow you to interact and share information with different consumers in django channels. This allows each consumer to communicate with the rest. For example, when in a chat a user sends a message, everyone can read the message, when a user leaves a room, everyone can know that he left it. With this capability it is possible to create a distributed application in which information is shared among the different users.

Django channels: channel layers, groups and users

Why Django channels? Because Django does not allow us to create applications with real-time communication natively. Django channels gives Django the ability to handle protocols that require a persistent connection, such as WebSockets, MQTT, chatbots, while keeping intact its integration with the session system, authentication and the rest of the framework.&#xA;Django channels places an intermediate layer that is in charge of processing http requests to django views and websocket connections to an http consumer or a websocket consumer.

Django channels: consumers, environments and events

These last few months I have been learning go. How did it all start? Well, it started in a rather superficial way; I loved their mascot, yes, that&rsquo;s really what it was all about. So after a brief mental debate, I decided to give the language a try. My first impression of it is that it is quite similar to Python; simple and easy to learn. Now that I have used it a bit more I bring you a comparison of Python vs Go, where I will explain some of their differences, in case you are interested in learning one or the other this 2024.

Python vs Go Which is the Best Programming Language in 2024?

Normally graphql is used in conjunction with Nodejs and express, or other javascript frameworks, to create a graphql API in which to make queries, but graphql can also be implemented with Python frameworks such as Django. We are going to create a django application that serves content with graphql using a cool library called graphene that abstracts almost all the boilerplate of integrating graphql with Django models.&#xA;Why graphql? Graphql allows you to integrate requests from multiple sources into a single API call.

Graphql and django with graphene

Typescript requires that we specify the types for the different variables and function arguments in React. When they are native types it is not intrincate, but for React components it can be different. Here are 3 ways to specify types for React components that contain children as part of their props.&#xA;<h2 id="types-with-reactnode">Types With ReactNode</h2>&#xA;The easiest way is manually, by specifying children as an optional React node.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-javascript" data-lang="javascript">import React from &#39;react&#39;&#xA;&#xA;type props = {&#xA; children?: React.ReactNode&#xA;}&#xA;&#xA;const MyComponent = ({ children }: Props) =&gt; {&#xA; return (&#xA; &lt;div&gt;&#xA; {children} &#xA; &lt;/div&gt;&#xA; )&#xA;}&#xA;&#xA;export default MyComponent&#xA;</code></pre></div><h2 id="using-reactfc">Using React.FC</h2>&#xA;The second way is to use a FC (Functional Component) object provided by React, which leaves implicit the use of children and also prevents us from returning undefined. Consider that using React.FC is &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/why-using-react.fc-could-be-a-bad-practice/">considered by some developers as a bad practice</a>&#xA;.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-javascript" data-lang="javascript">import React from &#39;react&#39;&#xA;&#xA;const MyComponent: React.FC&lt;{}&gt; = ({ children }) =&gt; {&#xA; return (&#xA; &lt;div&gt;&#xA; {children} &#xA; &lt;/div&gt;&#xA; )&#xA;}&#xA;&#xA;export default MyComponent&#xA;</code></pre></div><h2 id="reactpropswithchildren">React.PropsWithChildren</h2>&#xA;The last way is to make use of the PropsWithChildren object provided by React which, as its name says, already includes the props with the children component, ready to be used directly.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-javascript" data-lang="javascript">import React from &#39;react&#39;&#xA;&#xA;type Props = React.PropsWithChildren&lt;{}&gt;&#xA;&#xA;const MyComponent = ({ children }: Props) =&gt; {&#xA; return (&#xA; &lt;div&gt;&#xA; {children} &#xA; &lt;/div&gt;&#xA; )&#xA;}&#xA;&#xA;export default MyComponent&#xA;</code></pre></div>See what Typescript has to say on React at &#xA;&#xA;<a class="markdown-link" href="https://www.typescriptlang.org/docs/handbook/jsx.html#react-integration" rel="noopener" target="_blank">their official documentation</a>&#xA;&#xA;

Typescript requires that we specify the types for the different variables and function arguments in React. When they are native types it is not intrincate, but for React components it can be different. Here are 3 ways to specify types for React components that contain children as part of their props.&#xA;Types With ReactNode The easiest way is manually, by specifying children as an optional React node.&#xA;import React from &#39;react&#39; type props = { children?

Types for React components with children

There are quite simple to use tools that allow us to audit the number of requests per second (rps) that a website supports, locust is one of them, it is made with Python and with a minimal configuration allows us to process information and obtain graphs instantly, and in real time, of the behavior of our website.&#xA;Install locust The first step is to install it using pip or any virtual environment manager.

How to measure requests per second with locust in python?

The facebook chat plugin allows you to add a page button that connects to the chat of a facebook fanpage. But, as you know, facebook is monopolistic and the default installation loads the plugin first, making your website slower and affecting the web vitals indicators of the pages. There are some ways to mitigate this.&#xA;<h2 id="the-impact-of-the-facebook-chat-plugin">The impact of the facebook chat plugin</h2>&#xA;Loading the facebook plugin triggers a long list of web requests that download about many MB of information and consumes valuable time that can impact your page load, watch.&#xA;<a href="images/CargaArchivosDelFacebookChatPlugin.gif" aria-label="Downloads triggered by the facebook chat plugin">&#xA;&#xA; <img class="md-image" width="851" height="933" loading="lazy" src="images/CargaArchivosDelFacebookChatPlugin.gif" alt="Downloads triggered by the facebook chat plugin"/>&#xA;&#xA;</a>&#xA;95 requests and about 3 mb downloaded, 4 seconds.&#xA;Third-party plugins can strongly impact the metrics and performance of your web pages, both frontend and backend.&#xA;<h2 id="delay-plugin-loading">Delay plugin loading</h2>&#xA;The facebook plugin requires two html tags:&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-html" data-lang="html">&lt;!-- Messenger plugin de chat Code --&gt;&#xA;&lt;div id=&#34;fb-root&#34;&gt;&lt;/div&gt;&#xA;&lt;!-- Your plugin de chat code --&gt;&#xA;&lt;div id=&#34;fb-customer-chat&#34; class=&#34;fb-customerchat&#34;&gt;&lt;/div&gt;&#xA;</code></pre></div>To mitigate the effect of the facebook chat plugin several actions can be performed: we can delay its loading until a certain amount of time has elapsed, also delay it until a user interaction among other things. The optimal solution depends on how your users behave and the website you have.&#xA;I will delay loading until the user interacts with the chat.&#xA;To begin with, we will place a fake icon in place of the original one. This icon is the same one that facebook downloads. Since it is a simple image, it does not load any JS code nor is it accompanied by any request to the facebook servers.&#xA;We will identify this fake facebook icon by its id: fb-chat-logo&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-html" data-lang="html">&lt;div class=&#34;position-fixed&#34; id=&#34;fb-chat-logo&#34; style=&#34;bottom: 20px;right:20px; z-index: 1;&#34;&gt;&lt;svg width=&#34;60px&#34; height=&#34;60px&#34; viewBox=&#34;0 0 60 60&#34; cursor=&#34;pointer&#34;&gt;&lt;svg x=&#34;0&#34; y=&#34;0&#34; width=&#34;60px&#34; height=&#34;60px&#34;&gt;&lt;g stroke=&#34;none&#34; stroke-width=&#34;1&#34; fill=&#34;none&#34; fill-rule=&#34;evenodd&#34;&gt;&lt;g&gt;&lt;circle fill=&#34;#0A7CFF&#34; cx=&#34;30&#34; cy=&#34;30&#34; r=&#34;30&#34;&gt;&lt;/circle&gt;&lt;svg x=&#34;10&#34; y=&#34;10&#34;&gt;&lt;g transform=&#34;translate(0.000000, -10.000000)&#34; fill=&#34;#FFFFFF&#34;&gt;&lt;g id=&#34;logo&#34; transform=&#34;translate(0.000000, 10.000000)&#34;&gt;&lt;path d=&#34;M20,0 C31.2666,0 40,8.2528 40,19.4 C40,30.5472 31.2666,38.8 20,38.8 C17.9763,38.8 16.0348,38.5327 14.2106,38.0311 C13.856,37.9335 13.4789,37.9612 13.1424,38.1098 L9.1727,39.8621 C8.1343,40.3205 6.9621,39.5819 6.9273,38.4474 L6.8184,34.8894 C6.805,34.4513 6.6078,34.0414 6.2811,33.7492 C2.3896,30.2691 0,25.2307 0,19.4 C0,8.2528 8.7334,0 20,0 Z M7.99009,25.07344 C7.42629,25.96794 8.52579,26.97594 9.36809,26.33674 L15.67879,21.54734 C16.10569,21.22334 16.69559,21.22164 17.12429,21.54314 L21.79709,25.04774 C23.19919,26.09944 25.20039,25.73014 26.13499,24.24744 L32.00999,14.92654 C32.57369,14.03204 31.47419,13.02404 30.63189,13.66324 L24.32119,18.45264 C23.89429,18.77664 23.30439,18.77834 22.87569,18.45674 L18.20299,14.95224 C16.80079,13.90064 14.79959,14.26984 13.86509,15.75264 L7.99009,25.07344 Z&#34;&gt;&lt;/path&gt;&lt;/g&gt;&lt;/g&gt;&lt;/svg&gt;&lt;/g&gt;&lt;/g&gt;&lt;/svg&gt;&lt;/svg&gt;&lt;/div&gt;&#xA;</code></pre></div>Now, let&rsquo;s get and link this icon with mouseover, click, ontouchstart and ontouchmove events, so that any interaction with the icon will load the facebook code.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-javascript" data-lang="javascript">const fakeFbChatLogo = document.getElementById(&#39;fb-chat-logo&#39;);&#xA;&#xA;[&#39;click&#39;,&#39;ontouchstart&#39;, &#39;mouseover&#39;, &#39;ontouchmove&#39;].forEach(evt =&gt; &#xA; fakeFbChatLogo.addEventListener(evt, loadFacebookChat, false)&#xA;);&#xA;</code></pre></div>And we will pass it a function called loadFacebookChat that we will create next.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-javascript" data-lang="javascript">function loadFacebookChat() {&#xA; var chatbox = document.getElementById(&#39;fb-customer-chat&#39;);&#xA;&#xA; chatbox.setAttribute(&#34;page_id&#34;, &#34;TU_FACEBOOK_CHAT_ID&#34;);&#xA; chatbox.setAttribute(&#34;attribution&#34;, &#34;biz_inbox&#34;);&#xA;&#xA; (function(d, s, id) {&#xA; var js, fjs = d.getElementsByTagName(s)[0];&#xA; if (d.getElementById(id)) return;&#xA; js = d.createElement(s); js.id = id;&#xA; js.src = &#39;https://connect.facebook.net/es_LA/sdk/xfbml.customerchat.js&#39;;&#xA; fjs.parentNode.insertBefore(js, fjs);&#xA; }(document, &#39;script&#39;, &#39;facebook-jssdk&#39;));&#xA; [&#39;click&#39;,&#39;ontouchstart&#39;, &#39;mouseover&#39;, &#39;ontouchmove&#39;].forEach(evt =&gt; {&#xA; fakeFbChatLogo.removeEventListener(evt, loadFacebookChat, false)&#xA;});&#xA; // window needs to be the latest to prevent FB not defined &#xA; window.fbAsyncInit = function() {&#xA; FB.init({&#xA; xfbml : true,&#xA; version : &#39;v11.0&#39;&#xA; }) ;&#xA; // &#xA; FB.Event.subscribe(&#39;xfbml.render&#39;, function(){&#xA; FB.CustomerChat.show(true);&#xA; fakeFbChatLogo.remove(); &#xA; });&#xA; }&#xA;}&#xA;</code></pre></div>The content of the function is the same as you get from &#xA;&#xA;<a class="markdown-link" href="https://www.facebook.com/business/help/1524587524402327" rel="noopener" target="_blank">facebook documentation</a>&#xA; but with two small extra steps.&#xA;The first step is to remove the eventListener we created so that it will no longer be executed once the user interacts with the fake icon.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-javascript" data-lang="javascript">[&#39;click&#39;,&#39;ontouchstart&#39;, &#39;mouseover&#39;, &#39;ontouchmove&#39;].forEach(evt =&gt; {&#xA; fakeFbChatLogo.removeEventListener(evt, loadFacebookChat, false)&#xA;});&#xA;</code></pre></div>The second step is a subscription to the xfbml.render event, method that will be executed when our chat is rendered. It is optional to open the chat instantly for the user to see interaction, I have done it this way. And, as a final step, we remove our fake icon, so that it is not displayed along with the original.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-javascript" data-lang="javascript">FB.Event.subscribe(&#39;xfbml.render&#39;, function(){&#xA; FB.CustomerChat.show(true); //opcional&#xA; fakeFbChatLogo.remove(); &#xA; });&#xA; }&#xA;</code></pre></div>With the previous steps we are delaying the loading of the content until the user interacts with it. In this way the loading of the plugin is delayed until the user wants to use it, avoiding the impact on the initial load.&#xA;<a href="images/CargaRetardadaDelFacebookChatPlugin.gif" aria-label="Delayed loading of facebook plugin">&#xA;&#xA; <img class="md-image" width="407" height="365" loading="lazy" src="images/CargaRetardadaDelFacebookChatPlugin.gif" alt="Delayed loading of facebook plugin"/>&#xA;&#xA;</a>&#xA;The plug-in script is not activated until we interact with the icon&#xA;See how the fb appears to load normally and there is a small icon change, the animation or extra details you can customize to your liking with CSS and its animations.&#xA;

The facebook chat plugin allows you to add a page button that connects to the chat of a facebook fanpage. But, as you know, facebook is monopolistic and the default installation loads the plugin first, making your website slower and affecting the web vitals indicators of the pages. There are some ways to mitigate this.&#xA;The impact of the facebook chat plugin Loading the facebook plugin triggers a long list of web requests that download about many MB of information and consumes valuable time that can impact your page load, watch.

Facebook's plugin chat how to decrease its impact?

Python is super versatile, it has a giant community that has libraries that allow to achieve great things with few lines of code, Optical Character Recognition (OCR) is one of them, for that you just need to install tesseract and the python bindings, called pytesseract and you&rsquo;ll be ready to convert an image to a string.&#xA;<h2 id="installation-of-tesseract-ocr">Installation of tesseract-ocr</h2>&#xA;To perform OCR with Python we will need tesseract, which is the library that handles all the heavy lifting and image processing.&#xA;Make sure you install the newest tesseract-ocr, there is a huge difference between version 3 and versions after 4, as neural networks were implemented to improve character recognition. I am using version 5 alpha.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">sudo apt install tesseract-ocr&#xA;tesseract -v&#xA;tesseract 5.0.0-alpha-20201224-3-ge1a3&#xA;</code></pre></div>Differences in OCR engine efficiency between tesseract 3 and tesseract 5 alpha.&#xA;<a href="images/OCRTesseractVersion5vsVersion3-2.png" aria-label="Version 5 shows better performance">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="1200" height="630" loading="lazy" src="images/OCRTesseractVersion5vsVersion3-2.png" alt="Version 5 shows better performance"/>&#xA; <figcaption>Comparison between OCR performance of tesseract 3 and tesseract 5</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;<h3 id="installing-languages-in-tesseract">Installing languages in tesseract</h3>&#xA;We can see which languages are installed with &ndash;list-langs.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">tesseract --list-langs&#xA;</code></pre></div>It is obvious, but it is necessary to mention that the extent to which it recognizes the text will depend on whether we use it in the correct language. Let&rsquo;s install the Spanish language.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">sudo apt install tesseract-ocr-spa&#xA;tesseract --list-langs&#xA;List of available languages (3):&#xA;eng&#xA;osd&#xA;spa&#xA;</code></pre></div>You will see that Spanish is now installed and we can use it to detect the text in our images by adding the -l spa option to the end of our command&#xA;<h2 id="ocr-with-tesseract">OCR with tesseract</h2>&#xA;Now let&rsquo;s put it to the test to recognize text in images, straight from the terminal. I am going to use the following image:&#xA;<a href="images/imagen_con_texto.jpg" aria-label="Image with text to be processed">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="386" height="430" loading="lazy" src="images/imagen_con_texto.jpg" alt="Image with text to be processed"/>&#xA; <figcaption>File: image_with_text.jpg</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">tesseract image_with_text.jpg -&#xA;Warning: Invalid resolution 0 dpi. Using 70 instead.&#xA;Estimating resolution as 139&#xA;Do you have the time to listen to me whine&#xA;...&#xA;</code></pre></div>The &ldquo;-&rdquo; at the end of the command tells tesseract to send the results of the analysis to the standard output, so that we can view them in the terminal.&#xA;It is possible to tell tesseract which OCR engine to use:&#xA;<ul>&#xA;<li>0: for the original tesseract</li>&#xA;<li>1: for neural networks</li>&#xA;<li>2: tesseract and neural networks</li>&#xA;<li>3: Default, whichever is available</li>&#xA;</ul>&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">tesseract image_with_text.jpg - --oem 1&#xA;</code></pre></div>Consider that not all language files work with the original tesseract (0 and 3). Although generally the neural networks one is the one that gives the best result. You can find the models compatible with the original tesseract and neural networks in the &#xA;&#xA;<a class="markdown-link" href="https://github.com/tesseract-ocr/tessdata" rel="noopener" target="_blank">tesseract repository</a>&#xA;.&#xA;You can install them manually by downloading them and moving them to the appropriate folder, in my case it is /usr/local/share/tessdata/, but it may be different on your system.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">wget https://github.com/tesseract-ocr/tessdata/raw/main/eng.traineddata&#xA;sudo mv eng.traineddata /usr/local/share/tessdata/&#xA;</code></pre></div><h2 id="ocr-with-pytesseract">OCR with Pytesseract</h2>&#xA;<h3 id="installing-pytesseract">Installing pytesseract</h3>&#xA;After installation we add pytesseract (the python bindings) and pillow (for image management) to our virtual environment.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">pip install pytesseract pillow&#xA;</code></pre></div><h3 id="read-strings-from-images-with-pytesseract">Read strings from images with pytesseract</h3>&#xA;First let&rsquo;s check the languages we have installed.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">import pytesseract&#xA;from PIL import Image&#xA;import pytesseract&#xA;&#xA;print(pytesseract.get_languages())&#xA;# [&#39;eng&#39;, &#39;osd&#39;, &#39;spa&#39;]&#xA;</code></pre></div>Now that we have the languages, we can read the text that&rsquo;s in our images and process it as a string in our script.&#xA;The code is quite short and self-explanatory. Basically we pass the image as an argument to pytesseract&rsquo;s image_to_string method.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">import pytesseract&#xA;&#xA;from PIL import Image&#xA;import pytesseract&#xA;&#xA;img = Image.open(&#34;image_with_text.jpg&#34;) # Open the image with pillow&#xA;img.load()&#xA;text = pytesseract.image_to_string(img, lang=&#39;eng&#39;) # Extract image&#39;s text&#xA;print(text)&#xA;&#xA;# Do you have the time to listen to me whine...&#xA;</code></pre></div>image_to_string method can receive as argument the language in which we want it to detect the text.&#xA;Tesseract when with a method with which we can obtain much more information from the image, image_to_data, available for versions higher than 3.05.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">data = pytesseract.image_to_data(img)&#xA;print(data)&#xA;</code></pre></div><a href="images/dataTesseract.png" aria-label="Return from image_to_data method in tesseract">&#xA;&#xA; <img class="md-image" width="930" height="280" loading="lazy" src="images/dataTesseract.png" alt="Return from image_to_data method in tesseract"/>&#xA;&#xA;</a>&#xA;If you want to learn more visit the &#xA;&#xA;<a class="markdown-link" href="https://github.com/tesseract-ocr/tesseract" rel="noopener" target="_blank">complete tesseract documentation</a>&#xA;.&#xA;<h2 id="applications-of-ocr">Applications of OCR</h2>&#xA;OCR is quite useful for social networks, where you can scan the text that appears in the images to read its content and then process it or give it statistical treatment.&#xA;Here&rsquo;s another case, imagine a program that scans image boards or social networks, extracts a couple of images from the posted videos and links them to a tik tok account using the watermark that appears on each video.&#xA;&#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/my-analysis-of-anti-bot-captchas-and-their-advantages-and-disadvantages/">Captcha resolution</a>&#xA; is also one of the most interesting uses of OCR.&#xA;Or maybe a page that uploads images of your products with your prices written on each of them. With OCR it is possible to get all their prices, and upload them to your database, downloading and processing their images.&#xA;Facebook must use some kind of similar technology to censor images that include offensive text, according to its policies, that are uploaded to its social network.&#xA;<a href="images/facebook-screenshot-ocr.jpg" aria-label="Facebook uses OCR to read the text on its images">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="727" height="542" loading="lazy" src="images/facebook-screenshot-ocr.jpg" alt="Facebook uses OCR to read the text on its images"/>&#xA; <figcaption>Facebook is capable of reading the text on its images</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;Another of the most common applications is the transformation of a pdf book into images to text, ideal for transforming old book scans to epub or text files.&#xA;As you can see it is quite useful, I think it is one of the IA applications that will not go away &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/the-rise-and-fall-of-the-ai-bubble/">when the AI bubble crashes</a>&#xA;.&#xA;

Python is super versatile, it has a giant community that has libraries that allow to achieve great things with few lines of code, Optical Character Recognition (OCR) is one of them, for that you just need to install tesseract and the python bindings, called pytesseract and you&rsquo;ll be ready to convert an image to a string.&#xA;Installation of tesseract-ocr To perform OCR with Python we will need tesseract, which is the library that handles all the heavy lifting and image processing.

OCR with tesseract, python and pytesseract

One of the things I like most about Django is its ORM; one of the reasons why this framework is so popular . On the other hand FastAPI does not have an ORM and focuses solely on serving endpoints, showing agnostic on the basis of data. There are enough options ORM to python: django-alchemy, peewee, ponyORM, tortoise. The latter, besides being asynchronous, is inspired by the django ORM, so its syntax is quite similar, even many tortoise functions share name with its Django counterpart, so users who use the Django ORM will save a lot of time learning tortoise functions.

Python tortoise ORM integration with FastAPI

One of the best features of django is that it has the django admin panel, a ready-to-use administration panel, with basic functions such as create, read, edit and delete models, users, groups and permissions. All ready to use just by setting up your application. But sometimes our needs are different, what if we want to modify the appearance or functions of the interface? Fortunately Django includes many functions to customize the behavior of the admin, I will explain some of them below.

The django admin panel and its customization

To use the cache in django, just follow three simple steps:&#xA;Install a caching system, be it redis, memcached, etc. Set the CACHES variable to the settings.py file of the project. Add the middleware necessary for django to return the cache before processing the view. Use the low-level cache to cache specific views or data (optional). Implementing a caching system allows you to greatly improve the performance of an application made in Django .

Caching in Django REST Framework using memcached

In addition to creating asynchronous tasks, celery also allows you to create periodic tasks, which are executed from time to time. This can be quite useful to give maintenance to the database from time to time, to send marketing or shopping cart recovery emails, perhaps even to empty the contents of some temporary cache in the database or any repetitive task where execution time is an important factor, that is, to improve the performance of a django application.&#xA;<h2 id="installation-and-configuration-of-celery-in-django">Installation and configuration of Celery in Django</h2>&#xA;The first step is to install Celery:&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">pip install &#34;celery==5.1.2&#34;&#xA;</code></pre></div>As with asynchronous tasks, we also need rabbitmq or another broker.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">sudo apt install rabbitmq-server&#xA;</code></pre></div>Next, at the same level as our configuration file, we will create a file called celery.py, where we will create a celery app and pass the django configuration to it.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python"># celeryApp/celery.py&#xA;import os&#xA;from celery import Celery&#xA;&#xA;os.environ.setdefault(&#39;DJANGO_SETTINGS_MODULE&#39;, &#39;celeryApp.settings&#39;)&#xA;app = Celery(&#39;celeryApp&#39;)&#xA;app.config_from_object(&#39;django.conf:settings&#39;, namespace=&#39;CELERY&#39;)&#xA;app.autodiscover_tasks()&#xA;</code></pre></div>If you have doubts about what each line means or what rabbitmq is for, please visit my post about celery and django.&#xA;We also import celery into our init_.py_ file in our django project.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python"># celeryApp/__init__.py&#xA;from .celery import app as celery_app&#xA;__all__ = (&#39;celery_app&#39;,)&#xA;</code></pre></div>Sounds pretty obvious, but still I remind you; your django application must be running for celery to work.&#xA;<h2 id="periodic-sending-of-tasks-with-crontab">Periodic sending of tasks with crontab</h2>&#xA;For this example we are going to send emails periodically. To achieve this, we are going to add our periodic tasks in the file we just created&#xA;First we are going to define the function that we want to execute, in this case it will only send an email, using the django function and taking the data of its arguments.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python"># celeryApp/celery.py&#xA;from django.core.mail import send_mail&#xA;# ...&#xA;&#xA;@app.task&#xA;def send_my_email(subject, message, fromEmail, recipients):&#xA; send_mail(&#xA; subject,&#xA; message,&#xA; fromEmail,&#xA; recipients,&#xA; fail_silently=False,&#xA; )&#xA;</code></pre></div>Now let&rsquo;s set up the celery configuration.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python"># celeryApp/celery.py&#xA;from django.core.mail import send_mail&#xA;# ...&#xA;&#xA;@app.on_after_configure.connect&#xA;def setup_periodic_tasks(sender, **kwargs):&#xA; sender.add_periodic_task(10.0, send_my_email.s(&#39;subject&#39;, &#39;message&#39;, &#39;from@example.com&#39;, [&#39;to@example.com&#39;]), name=&#39;Envia email cada 10 segundos&#39;)&#xA;&#xA;@app.task&#xA;def send_my_email(subject, message, fromEmail, recipients):&#xA; send_mail(&#xA; subject,&#xA; message,&#xA; fromEmail,&#xA; recipients,&#xA; fail_silently=False,&#xA; )&#xA;</code></pre></div>The decorator @app.on_after_configure tells celery that these functions will be programmed once the configuration is complete.&#xA;Our function is going to receive a messenger (sender) as a parameter, we will call its add_periodic_task() method to tell it how often we want our task to be executed and then we will call the s() method of the function we define.&#xA;add_periodic_task() receives as first argument the interval in seconds that we want to elapse between each task and the second is our function executing the s() method with its arguments.&#xA;We define our function and decorate it with @app.task.&#xA;For our periodic scheduling to work, celery needs to be running beat.&#xA;<h2 id="beat-in-celery">beat in celery</h2>&#xA;What is Beat? Beat is one of your services that takes care of scheduled tasks. Beat is in charge of reading and sending the scheduled tasks to the celery workers that will execute them.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">celery -A celeryApp beat -l info&#xA;</code></pre></div><a href="images/CeleryBeatRabbitMQEsquema.png" aria-label="Simplified diagram of celery beat operation">&#xA;&#xA; <img class="md-image" width="1200" height="630" loading="lazy" src="images/CeleryBeatRabbitMQEsquema.png" alt="Simplified diagram of celery beat operation"/>&#xA;&#xA;</a>&#xA;Celery Beat Schematic&#xA;Since beat needs to transmit its tasks to a worker, it will be necessary to create one.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">celery -A celeryApp worker -l info&#xA;</code></pre></div>Now celery will make sure that an email is sent every 10 seconds (pure spam, I know).&#xA;Once the celery services are running we will see how our function starts executing every 10 seconds.&#xA;<a href="images/EjecucionDeTareasPeriodicasCeleryBeat.png" aria-label="Periodic tasks running on console">&#xA;&#xA; <img class="md-image" width="1904" height="929" loading="lazy" src="images/EjecucionDeTareasPeriodicasCeleryBeat.png" alt="Periodic tasks running on console"/>&#xA;&#xA;</a>&#xA;Celery tasks within 10 seconds of each other&#xA;<h2 id="tasks-scheduled-with-crontab">Tasks scheduled with crontab</h2>&#xA;What if instead of specifying an interval to execute the tasks we want them to be executed on a specific date, for example: every Sunday at 1:30 am.&#xA;Instead of calculating the seconds we can create a more friendly format with the crontab utility provided by celery.&#xA;Yes, you are correct, crontab shares the format with the &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/cron-and-crontab-schedules-recurring-tasks/">crontab file used by the GNU/Linux cron daemon</a>&#xA;, which I already talked about in a post.&#xA;Crontab will ensure that the execution format is every Monday at 7:30 a.m.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python"># celeryApp/celery.py&#xA;from celery.schedules import crontab&#xA;&#xA;# ...&#xA;&#xA;@app.on_after_configure.connect&#xA;def setup_periodic_tasks(sender, **kwargs):&#xA; # ...&#xA; sender.add_periodic_task(&#xA; crontab(hour=7, minute=30, day_of_week=1),&#xA; send_my_email.s(&#39;subject&#39;, &#39;message&#39;, &#39;from@example.com&#39;, [&#39;to@example.com&#39;]),&#xA; )&#xA;# ...&#xA;</code></pre></div>You can see more details directly in the &#xA;&#xA;<a class="markdown-link" href="https://docs.celeryproject.org/en/stable/userguide/periodic-tasks.html" rel="noopener" target="_blank">Celery documentation</a>&#xA;&#xA;

In addition to creating asynchronous tasks, celery also allows you to create periodic tasks, which are executed from time to time. This can be quite useful to give maintenance to the database from time to time, to send marketing or shopping cart recovery emails, perhaps even to empty the contents of some temporary cache in the database or any repetitive task where execution time is an important factor, that is, to improve the performance of a django application.

Periodic Tasks with Celery and Django

Celery, in combination with Django serve to solve a problem: the lack of asynchrony in our application. Sending an email, processing some file or responding to a third party service will keep our execution waiting for the task to finish and, as a consequence, our user waiting.&#xA;Using celery is one of the things you can do to improve the performance of a Django application . And you can also create periodic tasks with celery and django.

Celery and django to run asynchronous tasks

Almost all complex Django applications need views for Login, Logout, reboot and password change, as well as user registration. However, both Django and Django REST Framework (DRF) are completely agnostic about their implementation, and delegate the responsibility for these functions to the users of their frameworks. Fortunately there are libraries that make this task quite simple.&#xA;If you are about to develop an API, I have a post with recommendations on REST API design that can be useful for you.

Login using Django Rest Framework DRF

We can use react memo and useCallback to prevent a component from being rendered, uselessly, multiple times by memoization. If you don&rsquo;t know what memoization is or don&rsquo;t understand what the react components, useCallback and memo are for, I have a post where I explain React&rsquo;s useCallback, useMemo and memo, and what they are for .&#xA;As of React 19 all these hooks are deprecated, so only use this post as a reference for legacy React versions, please do not implement these hooks in your application Let&rsquo;s start our example with the following component:

React memo, useMemo and useCallback to avoid React renderings

The useCallback, useMemo and memo functions are used to optimize React applications using memoization, avoiding useless renderings, each with their differences, similarities and use cases. These three functions should not be used indiscriminately, but only in those situations where their impact is less than the benefits they offer.&#xA;&#xA;&#xA;&#xA; &#xA; &#xA; As of React 19 all these hooks are deprecated, so only use this post as a reference for legacy React versions, please do not implement these hooks in your application&#xA;&#xA;&#xA;Visit my post where I share &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/5-cool-react-libraries-you-should-know-about/">5 React libraries</a>&#xA; that you can&rsquo;t miss in your arsenal.&#xA;<h2 id="memoization-and-object-handling-in-javascript">Memoization and object handling in Javascript</h2>&#xA;Before we start moving on to functions there are two concepts you need to understand first: memoization and Javascript&rsquo;s handling of objects. Move on to the useCallback part if you have already mastered them.&#xA;<h3 id="what-is-memoization">What is memoization?</h3>&#xA;Memoize means to memorize a value to avoid processing it again, generally used to save you the cost of producing a value over and over again.&#xA;Imagine that you want to multiply the numbers 17 and 19. You would take paper and pen or a calculator, perform the relevant operations and obtain the result: 323. If you are asked again the value of that multiplication, you will not take a new paper and pen to calculate again, but you will recite the number 323, without calculating it, from memory.&#xA;As long as they keep asking you for the multiplication of 17 and 19 you will be able to return an answer without recalculating it. You have just memorized the result of multiplying 17 and 19 and you can return it without having to recalculate it.&#xA;Now I will explain how Javascript handles objects.&#xA;<h3 id="how-does-javascript-handle-objects">How does Javascript handle objects?</h3>&#xA;In Javascript, when we compare two native values we will get the same result. However, objects, including functions, are not considered equal, even if they are identical.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-javascript" data-lang="javascript">2 === 2&#xA;true&#xA;&#39;hello world&#39; === &#39;hello world&#39;&#xA;true&#xA;const d = () =&gt; &#34;hello world&#34;&#xA;const c = () =&gt; &#34;hello world&#34;&#xA;d === c&#xA;false&#xA;//las funciones son idénticas, sin embargo, al ser objetos diferentes, no son iguales para JS&#xA;</code></pre></div>Another example:&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-javascript" data-lang="javascript">const A = {uno: 1, dos:2}&#xA;const B = {uno: 1, dos:2}&#xA;A===B&#xA;// false&#xA;</code></pre></div>Even if two objects are the same and have the same properties and values, since they are located at different memory addresses, they are considered two different objects by JavaScript.&#xA;<h2 id="object-creation-in-react">Object creation in React</h2>&#xA;The above applies exactly the same in React. Every time React creates a function it is creating a new object, different from the previous one, even if they fulfill the same function, line by line.&#xA;Look at the following code, every time the MyComponent component is rendered, React will create a new function called callback, different from the last rendering.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-javascript" data-lang="javascript">import { useCallback } from &#39;react&#39;;&#xA;&#xA;const MyComponent = ({prop}) =&gt; {&#xA; const callback = () =&gt; {&#xA; return &#39;Result&#39;&#xA; };&#xA; return &lt;ChildComponent callback={callback} /&gt;&#xA;}&#xA;</code></pre></div>Now that you know how JavaScript and React handle objects, let&rsquo;s get to the main topic.&#xA;<h2 id="differences-between-usecallback-usememo-and-memo">Differences between useCallback, useMemo and memo</h2>&#xA;To begin with we will say that useCallback, useMemo and memo are memoization functions, these functions will save us to recalculate something from scratch.&#xA;The basic differences between useCallback, useMemo and memo are summarized in the following table.&#xA;<ul>&#xA;<li>useCallback, memoizes functions, is a hook.</li>&#xA;<li>useMemo, memoizes values, it is a hook.</li>&#xA;<li>memo, memoizes components, it is a HOC.</li>&#xA;</ul>&#xA;<a href="images/Diferencias-React-useCallback-useMemo-memo.jpg" aria-label="Differences between useCallback, useMemo and memo">&#xA;&#xA; <img class="md-image" width="1200" height="630" loading="lazy" src="images/Diferencias-React-useCallback-useMemo-memo.jpg" alt="Differences between useCallback, useMemo and memo"/>&#xA;&#xA;</a>&#xA;Together, &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/react-memo-usememo-and-usecallback-to-avoid-react-renderings/">memo, useMemo and useCallback are used to avoid unnecessary renderings in React</a>&#xA;.&#xA;<h2 id="usecallback-memoize-functions">useCallback memoize functions</h2>&#xA;useCallback is a React hook that takes care of memoizing the functions so that they are not re-rendered when the components are mounted. It is very useful when transferring functions to child components.&#xA;The useCallback function accepts two arguments and returns a function. The first argument is the function to memoize and the second, like useEffect, is an array of variables to watch, so that React does not generate a new function with each rendering, as long as those variables do not change. As with useEffect we can also leave the array empty.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-javascript" data-lang="javascript">import { useCallback } from &#39;react&#39;&#xA;&#xA;const MyComponent = ({prop}) =&gt; {&#xA; const callback = () =&gt; {&#xA; return &#39;Result&#39;&#xA; };&#xA; const memoizedCallback = useCallback(callback, [prop])&#xA; return &lt;ChildComponent callback={memoizedCallback} /&gt;&#xA;}&#xA;</code></pre></div>I repeat, as long as the prop that receives the component called Component, remains constant, a new function will not be created, no matter how much the component is re-rendered.&#xA;<h2 id="usememo-memoizes-values">useMemo memoizes values</h2>&#xA;This function is a React hook used to memoize the value returned by a function. The useMemo function accepts two arguments and returns a value. The first argument is the function and the second, like useCallback, is an array of variables to watch, so that a new value will not be generated as long as those variables do not change.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-javascript" data-lang="javascript">import { useMemo } from &#39;react&#39;&#xA;&#xA;// Ideal para funciones costosas de ejecutar, como factoriales o cálculos complejos&#xA;const OtherComponent({value}) =&gt; {&#xA; const memoizedValue = useMemo(()=&gt;getExpensiveValue(value), [value])&#xA; return &lt;div&gt;...&lt;/div&gt;&#xA;}&#xA;</code></pre></div>Again, as long as value is kept constant, getExpensiveValue will not be executed with each rendering of the component, but the memoized value will be returned. As with useEffect we can also leave the array empty, instead of value.&#xA;<h2 id="memo-memoizes-components">memo memoizes components</h2>&#xA;Memo is not a hook, it is a High Order Component (HOC), i.e. a function that takes a component as a parameter and **returns a new component.&#xA;Memo checks if the props of the component it receives have changed, if they have not, it will return the memoized component, without rendering it again.&#xA;Again, unlike useCallback and useMemo, memo is not a hook, but a memoization function that runs on a component.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-javascript" data-lang="javascript">import { memo } from &#39;react&#39;&#xA;&#xA;const MyComponent = ({id, title}) =&gt; {&#xA; return &lt;div&gt;{id}{title}&lt;/div&gt;&#xA;}&#xA;&#xA;export default memo(MyComponent)&#xA;</code></pre></div>For example, imagine we have the above component. As long as id and title do not change, the component named Component, will not be rendered once again, but its memoized value will be returned.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-javascript" data-lang="javascript">import MyComponent from &#39;./MyComponent&#39;&#xA;&#xA;const ParentComponent = () =&gt; {&#xA; const {id, title} = getIdAndTitle()&#xA;&#xA; return(&#xA; &lt;&gt;&#xA; &lt;OtrosComponentes/&gt;&#xA; &lt;MyComponent id={id} title={title}/&gt;&#xA; &lt;/&gt;)&#xA;}&#xA;</code></pre></div><h3 id="memo-use-cases">memo use cases</h3>&#xA;Memo is ideal for components that:&#xA;<ul>&#xA;<li>Suffer multiple renderings with the use of the application and generally receive the same props.</li>&#xA;<li>Receive props that change infrequently or not at all.</li>&#xA;<li>Very bulky components that have a very large impact on performance.</li>&#xA;</ul>&#xA;Remember to check my post where I combine this &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/react-memo-usememo-and-usecallback-to-avoid-react-renderings/">memo and useCallback to avoid renderings in React</a>&#xA;.&#xA;See the &#xA;&#xA;<a class="markdown-link" href="https://es.reactjs.org/docs/hooks-reference.html" rel="noopener" target="_blank">official React hooks documentation</a>&#xA; if you want to learn more about it.&#xA;

The useCallback, useMemo and memo functions are used to optimize React applications using memoization, avoiding useless renderings, each with their differences, similarities and use cases. These three functions should not be used indiscriminately, but only in those situations where their impact is less than the benefits they offer.&#xA;As of React 19 all these hooks are deprecated, so only use this post as a reference for legacy React versions, please do not implement these hooks in your application Visit my post where I share 5 React libraries that you can&rsquo;t miss in your arsenal.

React useCallback, useMemo and memo, differences

Do you need to get the data associated with a postal code in Mexico for your Django application? I wrote a small library called django-postalcodes-mexico that downloads postal codes from SEPOMEX (México&rsquo;s Postal Codes official site) and creates an API endpoint that allows you to query a postal code in Mexico and receive the colonias that belong to that postal code, as well as their state and municipality.&#xA;If you are going to develop a REST API, I have a post with multiple &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/basic-characteristics-of-an-api-rest-api/">REST API design recommendations</a>&#xA; that may help you.&#xA;For this example I use Python 3.8, Django 3.2.5 and Pipenv version 2020.5.28.&#xA;<h2 id="installation">Installation</h2>&#xA;To install it we are going to use &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/pipenv-the-virtual-environment-manager-you-dont-know/">Pipenv</a>&#xA;, but you can use Poetry, &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/python-virtualenv-linux-basic-tutorial/">pip</a>&#xA; or any other virtual environment manager.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">pip install django-postalcodes-mexico django&#xA;django-admin startproject codigosPostalesMx .&#xA;python manage.py migrate&#xA;</code></pre></div>Next we install the package by adding it to INSTALLED_APPS in our configuration file.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">INSTALLED_APPS = [&#xA; &#39;django_postalcodes_mexico.apps.DjangoPostalcodesMexicoConfig&#39;,&#xA;]&#xA;</code></pre></div>We execute the migrations. This will create the tables needed to manage the postal codes.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">python manage.py migrate&#xA;</code></pre></div><h2 id="obtaining-mexicos-postal-codes-from-sepomex">Obtaining Mexico&rsquo;s postal codes from SEPOMEX</h2>&#xA;Now that the tables have been created we are going to install the Mexico postal codes directly from the SEPOMEX page with a single Django command.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">python manage.py importpostalcodesmx&#xA;Trying to connect to Mexican Postal Service (Correos de Mexico)&#xA;Response received&#xA;This process can take a few minutes, please be patient&#xA;Creating database...&#xA;The postal code database has been successfully populated&#xA;</code></pre></div>That&rsquo;s all, now we just need to import include and add our urls. I put the path api/ but you can use the one you want.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">from django.contrib import admin&#xA;from django.urls import path, include&#xA;&#xA;from django_postalcodes_mexico import urls as django_postalcodes_mexico_urls&#xA;&#xA;urlpatterns = [&#xA; # ...&#xA; path(&#39;api/&#39;, include(django_postalcodes_mexico_urls)),&#xA;]&#xA;</code></pre></div><h2 id="obtaining-information-from-a-postal-code">Obtaining information from a postal code</h2>&#xA;If we now make a request api/09000/ or any other 5-digit postal code we will receive a JSON response with the municipality, state and a list of neighborhoods.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">curl localhost:8000/api/09000/&#xA;{&#34;codigoPostal&#34;: &#34;09000&#34;, &#34;municipio&#34;: &#34;Iztapalapa&#34;, &#34;estado&#34;: &#34;Ciudad de M\u00e9xico&#34;, &#34;colonias&#34;: [&#34;La Asunci\u00f3n&#34;, &#34;San Ignacio&#34;, &#34;San Jos\u00e9&#34;, &#34;San Lucas&#34;, &#34;San Pablo&#34;, &#34;San Pedro&#34;, &#34;Santa B\u00e1rbara&#34;]}&#xA;</code></pre></div><a href="images/Api-codigos-postales-mx.png" aria-label="Django API query result for postal code &amp;ldquo;09000&amp;rdquo;">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="563" height="374" loading="lazy" src="images/Api-codigos-postales-mx.png" alt="Django API query result for postal code &amp;ldquo;09000&amp;rdquo;"/>&#xA; <figcaption>Django API query result for postal code 09000</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;A non-existent postal code will return a 404 status.&#xA;<a href="images/Captura-de-pantalla-de-2021-11-17-12-15-24.png" aria-label="Nonexistent postal code returning an error message">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="803" height="168" loading="lazy" src="images/Captura-de-pantalla-de-2021-11-17-12-15-24.png" alt="Nonexistent postal code returning an error message"/>&#xA; <figcaption>Nonexistent postal code returning an error message</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;While an invalid postal code will return a 400 error and an error message&#xA;<a href="images/Codigo-postal-invalido.png" aria-label="Invalid postal code returning an error">&#xA;&#xA;<figure>&#xA; <img class="md-image" width="960" height="355" loading="lazy" src="images/Codigo-postal-invalido.png" alt="Invalid postal code returning an error"/>&#xA; <figcaption>Invalid postal code returning an error</figcaption>&#xA;</figure>&#xA;&#xA;</a>&#xA;Read the short &#xA;&#xA;<a class="markdown-link" href="https://github.com/EduardoZepeda/django-postalcodes-mexico" rel="noopener" target="_blank">official documentation in my github repository</a>&#xA; for more information.&#xA;

Do you need to get the data associated with a postal code in Mexico for your Django application? I wrote a small library called django-postalcodes-mexico that downloads postal codes from SEPOMEX (México&rsquo;s Postal Codes official site) and creates an API endpoint that allows you to query a postal code in Mexico and receive the colonias that belong to that postal code, as well as their state and municipality.&#xA;If you are going to develop a REST API, I have a post with multiple REST API design recommendations that may help you.

Mexico Postal codes API with Django

The other day I was testing a library called htmx, which promises to make web creation much easier, yes, another library, but with the difference that this one doesn&rsquo;t need you to write Javascript (JS) and it also combines quite well with Django. Htmx bases all its operation on writing attributes in your HTML tags, which are responsible for abstracting all the JS that runs behind the scenes. The result is code consisting only of HTML tags and their attributes, with no JS code (well, maybe just a little).

Django and htmx, modern web apps without writing JS

JWTs (JSON Web Tokens) have become extremely popular, some even consider them a replacement for the classic tokens used by other frameworks, such as the Django Rest Framework. Using JWT or regular tokens (SWT) allows you to store all your session information directly on the token and they are also cryptographically signed, sounds good doesn&rsquo;t it?&#xA;What is JWT? JWT is a standard for the creation of JSON-based access tokens for the exchange of information between two parties.

Django Rest Framework and JWT to authenticate users

A Manager (or handler) is the interface through which query operations or queries from the database are provided to Django models. Yes, I mean that objects that goes after the name of your model; YourModel.objects.all() and Tumodel.objects.filter(). All Django models have at least one manager. Whenever you use the object manager (I will refer to it as manager from here on) in a database query using the Django ORM you are making use of its default object manager. These managers in Django can be customized to modify the objects returned by a query and we can customize them to our liking.&#xA;Before you start, if you don&rsquo;t know the basics of Django you can start with &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/the-definitive-guide-to-django/">the definitive guide to Django</a>&#xA;&#xA;On the other hand, if you are looking to optimize your Django app, probably my post where I talk about how to &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/how-to-scale-a-django-app-to-serve-one-million-users/">improve performance of slow Django apps</a>&#xA; will serve you better.&#xA;<h2 id="the-django-object-manager">The Django object manager</h2>&#xA;If you have used the Django ORM, you have probably already used the default manager. Objects is the name of the default manager and is responsible for returning all objects in a Django model.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">Videogame.objects.all()&#xA;</code></pre></div><h2 id="modifying-the-default-manager">Modifying the default manager</h2>&#xA;Perhaps we want to have two managers, one that returns all objects and another that returns the most recent objects, or objects created by a particular user, or objects filtered by a term.&#xA;Let&rsquo;s start by modifying the name of the default manager, to do so we just have to assign it to the Manager object of models.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">from django.db import models&#xA;&#xA; class Videogame(models.Model):&#xA; ...#&#xA; stem = models.Manager() #Esto te permitira llamar Videogame.stem.all() en lugar de Videogame.objects.all()&#xA;</code></pre></div>What is this for? Well, we can now call the object manager in a different way, which may improve the readability of our code, but it is not the most important reason.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">Videogame.stem.all()# En lugar de Videogame.objects.all()&#xA;</code></pre></div><h2 id="adding-methods-to-a-django-manager">Adding methods to a Django manager</h2>&#xA;A custom manager allows us to add new methods, which will give it unique behaviors. How? You can filter the results of a search, limit the results according to the user, a range of dates, a number of results, whatever you prefer.&#xA;Look at this example below, we instantiate a new manager called VideogameManager, which inherits from models.Manager. We add a method called count_titles that will be in charge of counting the results for a given search, nothing too complicated, we simply concatenate a filter with a query, as if it were any search.&#xA;Since we have this new manager with the count_titles method, we replace the objects property of our Videogame model with an instance of the manager we just created.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">from django.db import models&#xA;&#xA; class VideogameManager(models.Manager):&#xA; def contar_titulos(self, keyword):&#xA; return self.filter(titulo__icontains=keyword).count()&#xA; #self se refiere al manager en sí mismo&#xA; class Videogame(models.Model):&#xA; …&#xA; objects = VideogameManager() #Renombra al manager por defecto aquí se usa objects para ser consistente&#xA;</code></pre></div>Now our default manager, objects, has a method called count_titles that we can use as if it were part of the original Django ORM.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">Videogame.objects.contar_titulos(&#39;fantasy&#39;)&#xA;</code></pre></div><h2 id="modifying-the-initial-manager-querysets">Modifying the initial Manager QuerySets</h2>&#xA;A Manager&rsquo;s base QuerySet returns all objects in the system. But what if we are only interested in certain data? Imagine that the online store has a database of all video games, but, since we are basic geeks, we gave the squarenix company a special section.&#xA;If we write individual custom queries for each queryset in that section it would look something like this:&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">Videogames.objects.filter(company=&#34;squarenix&#34;).filter(titulo__icontains=&#34;Fantasy&#34;)&#xA;# ...&#xA;Videogames.objects.filter(company=&#34;squarenix&#34;).filter(descripcion__icontains=&#34;Aventura&#34;)&#xA;# ...&#xA;Videogames.objects.filter(company=&#34;squarenix&#34;).filter(genero=&#34;RPG&#34;)&#xA;</code></pre></div>As you know, the above repeats too much code, violating the DRY maxim.&#xA;We can replace the base QuerySet by overwriting the Manager.get_query_set() method so that the default queryset we get does the filtering by company name.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">from django.db import models&#xA;&#xA; # Primero, definimos una subclase para el Manager.&#xA; class SquarenixManager(models.Manager):&#xA; def get_query_set(self):&#xA; return super(SquarenixManager, self).get_query_set().filter(company=&#39;squarenix&#39;)&#xA;&#xA; # Despues lo anclamos al modelo Videogame explícitamente.&#xA; class Videogame(models.Model):&#xA; # ...&#xA; objects = models.Manager() # El manager predeterminado.&#xA; squarenix_videogames = SquarenixManager() # Nuestro manager&#xA;</code></pre></div>Note how we now have two managers. A Model can define several managers, the first manager that appears is the default manager (in the example above it is objects), which will be used by Django internally for other special features.&#xA;When running the manager it will return only the books that have Squarenix as company and, in addition, you can use all QuerySet methods on it.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">Videogame.objects.all() # Devuelve todos los videojuegos&#xA;Videogame.squarenix_videogames.all() # Devuelve solo los videojuegos de squarenix&#xA;Videogame.squarenix_videogames.filter(titulo__icontains=&#39;Kingdom Hearts&#39;) #Devuelve los videojuegos de squarenix cuyo título contenga Kingdom Hearts&#xA;</code></pre></div>And that&rsquo;s all. Now that you know that you can create as many managers as you want that will give you as many filtered searches as you need.&#xA;If you want to know more about managers, please check &#xA;&#xA;<a class="markdown-link" href="https://docs.djangoproject.com/en/3.2/topics/db/managers/" rel="noopener" target="_blank">the official Django documentation</a>&#xA;&#xA;

A Manager (or handler) is the interface through which query operations or queries from the database are provided to Django models. Yes, I mean that objects that goes after the name of your model; YourModel.objects.all() and Tumodel.objects.filter(). All Django models have at least one manager. Whenever you use the object manager (I will refer to it as manager from here on) in a database query using the Django ORM you are making use of its default object manager.

Managers or custom handlers in Django

What if a user&rsquo;s finger slips on the keyboard and types &ldquo;parfume&rdquo; instead of &ldquo;perfume&rdquo;. We probably don&rsquo;t want our user to leave the site because he didn&rsquo;t find any &ldquo;parfume&rdquo; on our website. Our website should return the results that most closely match what they are looking for. See how an experienced ecommerce handles it:&#xA;<a href="images/busquedaLaptopAmazon.gif" aria-label="Search for the word &amp;ldquo;parfume&amp;rdquo; on amazon">&#xA;&#xA; <img class="md-image" width="772" height="436" loading="lazy" src="images/busquedaLaptopAmazon.gif" alt="Search for the word &amp;ldquo;parfume&amp;rdquo; on amazon"/>&#xA;&#xA;</a>&#xA;Don&rsquo;t you remember the basic searches in Django? I have a post about &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/full-text-search-and-searches-with-django-and-postgres/">basic searches and full text search using Django and Postgres</a>&#xA;, if you haven&rsquo;t read it take a look there first.&#xA;<h2 id="trigrams-in-django-and-postgres">Trigrams in Django and Postgres</h2>&#xA;But how does our application know that when a user types &ldquo;parfume&rdquo; they probably mean &ldquo;perfume&rdquo;?&#xA;The reason why parfume resembles perfume is because both contain similar trigrams.&#xA;Trigram? Yes, trigram, of three and gram. **A trigram is three consecutive characters, it&rsquo;s as simple as that.&#xA;<a href="images/trigramas.jpg" aria-label="Automata trigrams schematic">&#xA;&#xA; <img class="md-image" width="600" height="600" loading="lazy" src="images/trigramas.jpg" alt="Automata trigrams schematic"/>&#xA;&#xA;</a>&#xA;Trigrams are three consecutive characters&#xA;<h2 id="trigrams-and-similar-words">Trigrams and similar words</h2>&#xA;According to &#xA;&#xA;<a class="markdown-link" href="https://www.postgresql.org/docs/12/pgtrgm.html" rel="noopener" target="_blank">Postgres</a>&#xA;, we can tell how similar two strings are by comparing the number of trigrams they share, and Django provides functions to work with trigrams.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">Videogame.objects.filter(name__trigram_similar=&#34;automatta&#34;) # it should say automata&#xA;&lt;QuerySet [&lt;Videogame: Nier automata&gt;]&gt;&#xA;Videogame.objects.filter(name__trigram_similar=&#34;autommattaa&#34;) # it should say automata&#xA;&lt;QuerySet [&lt;Videogame: Nier automata&gt;]&gt;&#xA;#...FROM &#34;videogame_videogame&#34; WHERE UNACCENT(&#34;videogame_videogame&#34;.&#34;name&#34;) % UNACCENT(autommata)&#xA;</code></pre></div>View the trigrams for the word &ldquo;automata&rdquo; directly from the postgres terminal&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-sql" data-lang="sql">SELECT show_trgm(&#39;automata&#39;);&#xA; show_trgm &#xA;---------------------------------------------&#xA; {&#34; a&#34;,&#34; au&#34;,ata,aut,mat,oma,&#34;ta &#34;,tom,uto}&#xA;</code></pre></div>Now look at the trigrams for &ldquo;automatta&rdquo; (if you didn&rsquo;t notice, this one has a double &ldquo;t&rdquo;).&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-sql" data-lang="sql">SELECT show_trgm(&#39;autommattaa&#39;);&#xA; show_trgm &#xA;---------------------------------------------------------&#xA; {&#34; a&#34;,&#34; au&#34;,&#34;aa &#34;,att,aut,mat,mma,omm,taa,tom,tta,uto}&#xA;</code></pre></div>Can you notice how they both share some trigrams (a, au, aut, mat, tom, uto)?&#xA;<a href="images/TrigramasCompartidos.png" aria-label="Shared trigrams between two text strings">&#xA;&#xA; <img class="md-image" width="1200" height="630" loading="lazy" src="images/TrigramasCompartidos.png" alt="Shared trigrams between two text strings"/>&#xA;&#xA;</a>&#xA;Also note that the quotation marks around certain trigrams are to specify trigrams with spaces.&#xA;The number of trigrams shared by a pair of text strings can be expressed by means of an index. The more trigrams shared, the higher this index will be.&#xA;We can find the similarity index, according to their trigrams, between two words from the postgres terminal.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-sql" data-lang="sql">SELECT word_similarity(&#39;outer worlds&#39;, &#39;wilds&#39;);&#xA; word_similarity &#xA;-----------------&#xA; 0.1875&#xA;</code></pre></div><h3 id="sort-by-similarity-with-trigrams">Sort by similarity with trigrams</h3>&#xA;What if we want our Django search to find even those words that match in a smaller number of trigrams?&#xA;Using the Django ORM with the TrigramSimilarity function we can filter those results by setting a similarity threshold between a search word and our data.&#xA;If you don&rsquo;t remember what Django annotate is for, I have a post where I explain &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/django-annotate-and-aggregate-explained/">django annotate and aggregate, as well as their differences</a>&#xA;&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">from django.contrib.postgres.search import TrigramSimilarity&#xA;&#xA;results = Videogame.objects.annotate(similarity=TrigramSimilarity(&#39;name&#39;, &#39;wilds&#39;), ).filter(similarity__gt=0.1).order_by(&#39;-similarity&#39;)&#xA;&lt;QuerySet [&lt;Videogame: Outer wilds&gt;, &lt;Videogame: Outer worlds&gt;]&gt; # With a similarity index of 0.1, the words wilds y worlds match&#xA;results[0].similarity&#xA;# 0.5&#xA;# ...SIMILARITY(&#34;videogame_videogame&#34;.&#34;name&#34;, wilds) AS &#34;similarity&#34; FROM &#34;videogame_videogame&#34; WHERE SIMILARITY(&#34;videogame_videogame&#34;.&#34;name&#34;, wilds) &gt; 0.1 ORDER BY &#34;similarity&#34; DESC&#xA;</code></pre></div><h2 id="search-rank-to-sort-by-relevance">Search rank to sort by relevance</h2>&#xA;If a user searches for a laptop and your application first shows them laptop cases, laptop backpacks, other related items and then laptops, you are providing an inadequate user experience.&#xA;<a href="images/busquedaLaptopAmazon.gif" aria-label="Search for the word &amp;ldquo;laptop&amp;rdquo; on amazon">&#xA;&#xA; <img class="md-image" width="772" height="436" loading="lazy" src="images/busquedaLaptopAmazon.gif" alt="Search for the word &amp;ldquo;laptop&amp;rdquo; on amazon"/>&#xA;&#xA;</a>&#xA;Search Rank allows you to sort user searches by relevance, so that your user finds exactly what they are looking for first and then everything else.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">from django.contrib.postgres.search import SearchQuery, SearchRank, SearchVector&#xA;&#xA;vector = SearchVector(&#39;name&#39;)&#xA;query = SearchQuery(&#39;days&#39;)&#xA;results = Videogame.objects.annotate(rank=SearchRank(vector, query)).order_by(&#39;-rank&#39;)&#xA;results[0].rank&#xA;# 0.0607927&#xA;# ... ts_rank(to_tsvector(COALESCE(&#34;videogame_videogame&#34;.&#34;name&#34;, )), plainto_tsquery(days)) AS &#34;rank&#34; FROM &#34;videogame_videogame&#34; ORDER BY &#34;rank&#34; DESC&#xA;</code></pre></div>Search Rank, with the help of the to_tsvector and plainto_tsquery function, will sort our search results according to the matches it finds between the vector and the query and **return each of the results of our query with a rank property that shows the value for its respective element.&#xA;<h3 id="assign-importance-by-field">Assign importance by field</h3>&#xA;In a search, not all fields should matter equally&#xA;Imagine you have a book database and a Book model with a title field and a content field. If a user searches for &ldquo;magic&rdquo; books, it would probably be correct to return books that contain &ldquo;magic&rdquo; in the title, such as &ldquo;Magic spells and ceremonies&rdquo; or &ldquo;Magic rituals&rdquo; or &ldquo;History of magic&rdquo;.&#xA;On the other hand, Harry Potter books also relate to user interests, as they mention the word &ldquo;magic&rdquo; multiple times in their description, however, you probably want your search to prioritize those that contain the word &ldquo;magic&rdquo; in the title, not in the description.&#xA;<a href="images/ExplicacionRelevancia.jpg" aria-label="Explanation of relevance according to the field">&#xA;&#xA; <img class="md-image" width="894" height="477" loading="lazy" src="images/ExplicacionRelevancia.jpg" alt="Explanation of relevance according to the field"/>&#xA;&#xA;</a>&#xA;With Posgres the above is possible.&#xA;To do this, we assign a weight, weighting, priority or whatever you want to call it, in the form of a letter, to each search vector, together with the name of the field to which it corresponds, and we join them into one.&#xA;We can choose between the letters &ldquo;A&rdquo;, &ldquo;B&rdquo;, &ldquo;C&rdquo; and &ldquo;D&rdquo;. Each letter will have a different value of relevance in our search; &ldquo;A&rdquo; for the highest value and &ldquo;D&rdquo; for the lowest.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">from django.contrib.postgres.search import SearchQuery, SearchRank, SearchVector&#xA;vector = SearchVector(&#39;title&#39;, weight=&#39;A&#39;) + SearchVector(&#39;descripcion&#39;, weight=&#39;B&#39;)&#xA;query = SearchQuery(&#39;Magic&#39;)&#xA;Book.objects.annotate(rank=SearchRank(vector, query)).filter(rank__gte=0.3).order_by(&#39;rank&#39;)&#xA;</code></pre></div>Exactly they have the following values:&#xA;<ul>&#xA;<li>D = 0.1</li>&#xA;<li>C = 0.2</li>&#xA;<li>B = 0.4</li>&#xA;<li>A = 1.0</li>&#xA;</ul>&#xA;These values can be overwritten to suit your needs, according to the type of business and models you use.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">Book.objects.annotate(rank=SearchRank(vector, query), weights=[0.1, 0.2, 0.3, 0.9]).filter(rank__gte=0.3).order_by(&#39;rank&#39;).filter(rank__gte=0.3).order_by(&#39;rank&#39;)&#xA;</code></pre></div>In the example above, I have rewritten the original values and decreased the values of the letters &ldquo;D&rdquo;, &ldquo;C&rdquo;, &ldquo;B&rdquo; so that they represent a much smaller percentage compared to the letter &ldquo;A&rdquo;.&#xA;<h2 id="django-libraries-for-advanced-searches">Django Libraries for advanced searches</h2>&#xA;Perhaps your search needs are much more advanced than those provided by the Django ORM combined with Postgres. But, unless you are developing something that will revolutionize the search industry, someone has already gone through the same problem. There are generic solutions, such as &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/searches-with-solr-with-django-haystack/">Solr and Django-haystack</a>&#xA;, that save you from writing many, many lines of code. Some examples are:&#xA;<ul>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://xapian.org/" rel="noopener" target="_blank">Xapian</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://whoosh.readthedocs.io/en/latest/intro.html" rel="noopener" target="_blank">Whoosh</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://django-haystack.readthedocs.io/en/master/index.html" rel="noopener" target="_blank">Django haystack</a>&#xA;</li>&#xA;<li>&#xA;&#xA;<a class="markdown-link" href="https://github.com/etianen/django-watson" rel="noopener" target="_blank">Django watson</a>&#xA;</li>&#xA;</ul>&#xA;

What if a user&rsquo;s finger slips on the keyboard and types &ldquo;parfume&rdquo; instead of &ldquo;perfume&rdquo;. We probably don&rsquo;t want our user to leave the site because he didn&rsquo;t find any &ldquo;parfume&rdquo; on our website. Our website should return the results that most closely match what they are looking for. See how an experienced ecommerce handles it:&#xA;Don&rsquo;t you remember the basic searches in Django? I have a post about basic searches and full text search using Django and Postgres , if you haven&rsquo;t read it take a look there first.

Trigrams and advanced searches with Django and Postgres

Sometimes when we type we make a mistake in a letter, we can repeat it, omit it or change it for another one. That mistake can lead to a series of different results in a web search, or even no results at all. Maybe for a blog it does not represent a threat, but for an ecommerce it can mean the loss of a sale, and for those stores with a huge traffic, a successful text search, either using full text search or something more complex, in Django or another framework, can represent the difference between losses or huge profits.

Full text search and searches with Django and Postgres

I ran into Ngrok trying to redirect a Mercado Pago payment notification to my localhost, for testing purposes. It worked more or less like this: Mercado Pago gave you a url address to redirect the buyer to make the payment. Once the payment was finished, Mercado Pago would make an HTTP request to any url address that you indicated and would send by POST the results of the payment attempt. The problem is that Mercado Pago does not send notifications to localhost.&#xA;<h2 id="ngrok-allows-you-to-share-your-localhost-externally">Ngrok allows you to share your localhost externally</h2>&#xA;What Ngrok does is to serve as a tunnel that redirects any web request, through its own urls, to your localhost. This can be used to test a webhook or receive notifications, a very common task in payment gateways, share your localhost with collaborators without needing your own domain, etc.&#xA;<a href="images/EsquemaNgrok.png" aria-label="ngrok operation schematic">&#xA;&#xA; <img class="md-image" width="1000" height="600" loading="lazy" src="images/EsquemaNgrok.png" alt="ngrok operation schematic"/>&#xA;&#xA;</a>&#xA;<h2 id="ngrok-installation">Ngrok installation</h2>&#xA;To install Ngrok let&rsquo;s go to &#xA;&#xA;<a class="markdown-link" href="https://ngrok.com/" rel="noopener" target="_blank">their website</a>&#xA; and create an account or log in. You can use Github or Gmail if you don&rsquo;t want to register and follow the installation instructions.&#xA;<h2 id="basic-use-of-ngrok">Basic use of ngrok</h2>&#xA;To run ngrok on GNU/Linux just run the executable, followed by the http option and a port number. I used 8080 but you can use the one you prefer.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">./ngrok http 8080&#xA;</code></pre></div>If everything worked correctly, you will see something similar to the following.&#xA;<a href="images/NgrokTerminal.png" aria-label="Ngrok information in the terminal">&#xA;&#xA; <img class="md-image" width="905" height="281" loading="lazy" src="images/NgrokTerminal.png" alt="Ngrok information in the terminal"/>&#xA;&#xA;</a>&#xA;What does the above display mean? It means that all requests made to &#xA;&#xA;<a class="markdown-link" href="http://fc2ca35fd170.ngrok.io" rel="noopener" target="_blank">http://fc2ca35fd170.ngrok.io</a>&#xA;; that is, to the fc2ca35fd170 subdomain of the ngrok domain, will be redirected to your localhost, specifically to port 8080. And that&rsquo;s it, it&rsquo;s that simple and easy to use.&#xA;<h2 id="using-ngrok-with-django">Using Ngrok with Django</h2>&#xA;For this example I redirected a Django application on port 8000, instead of port 8080.&#xA;If you have no idea how to use Django I have some book recommendations: &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/the-definitive-guide-to-django/">Django la guia definitiva</a>&#xA; and &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/learning-django-through-the-book-django-by-example-my-review/">Django by example</a>&#xA;.&#xA;Remember to add the domain, with its subdomain to the ALLOWED_HOSTS variable in the configuration file.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python"># app/settings.py&#xA;ALLOWED_HOSTS = [&#39;8da947737113.ngrok.io&#39;]&#xA;</code></pre></div>Let&rsquo;s run the Django server, by default it will run on port 8000&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">python manage.py runserver&#xA;</code></pre></div>If we now run ngrok, specify port 8000 and access the address it indicates, we will see our application.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">ngrok http 8000&#xA;</code></pre></div><a href="images/NgrokEjemploDjango.png" aria-label="Ngrok information for the Django example">&#xA;&#xA; <img class="md-image" width="892" height="235" loading="lazy" src="images/NgrokEjemploDjango.png" alt="Ngrok information for the Django example"/>&#xA;&#xA;</a>&#xA;Observe the domain in which our Django application is running.&#xA;<a href="images/NgrokTunnel-1.png" aria-label="Django application running in Ngrok domain">&#xA;&#xA; <img class="md-image" width="1218" height="694" loading="lazy" src="images/NgrokTunnel-1.png" alt="Django application running in Ngrok domain"/>&#xA;&#xA;</a>&#xA;We are able to make our application accessible to anyone who has the url that ngrok provides us with!&#xA;

I ran into Ngrok trying to redirect a Mercado Pago payment notification to my localhost, for testing purposes. It worked more or less like this: Mercado Pago gave you a url address to redirect the buyer to make the payment. Once the payment was finished, Mercado Pago would make an HTTP request to any url address that you indicated and would send by POST the results of the payment attempt. The problem is that Mercado Pago does not send notifications to localhost.

Ngrok, your localhost accessible from the internet

When I first learned that Django had a permissions system, many years ago, it seemed rather esoteric, not very useful and easy to replicate, how wrong I was back then. Then I realized that the built-in permissions system was a marvel and saved a lot of code, and was quite robust and tested by some of the largest companies in the world.&#xA;If you have not yet decided to use Django and are investigating its features check out my post on the advantages and disadvantages of the Django web development framework .

How do permissions and its groups work in Django?

The other day I was solving a kata in &#xA;&#xA;<a class="markdown-link" href="http://www.codewars.com/r/qsX8Ww" rel="noopener" target="_blank">codewars</a>&#xA;, one of the steps of the problem needed a two-dimensional array, in more mundane words: an array of arrays. In Python it is super simple to create a two-dimensional array using the multiplication operator, as if it were numbers.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">arr = [0]*5&#xA;#[0, 0, 0, 0, 0]&#xA;</code></pre></div>If you have no idea what I&rsquo;m talking about, I have an excellent resource that can help you a lot: &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/learn-python-from-scratch-with-this-free-book/">&ldquo;Inmersion en Python&rdquo;, totally free and in Spanish</a>&#xA;&#xA;<h2 id="the-wrong-way-to-create-arrays-in-python">The wrong way to create arrays in Python</h2>&#xA;Knowing how to create arrays using the multiplication operator, we could think of creating a two-dimensional array as follows:&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">matrix = [[0]*4]*4&#xA;#[[0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0]]&#xA; #&#xA;</code></pre></div>So far so good, we already have our matrix. But, what if we want to change the second element of the first element of our matrix (I have marked it with a hashtag above).&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">matrix[0][1] = 3&#xA;#[[0, 3, 0, 0], [0, 3, 0, 0], [0, 3, 0, 0], [0, 3, 0, 0]]&#xA;</code></pre></div>What happened? We modified a single element and all of them have been modified. And not only that, but the modified elements always correspond to the second element. Why is it that when we change one element of an array in Python they are all changed?&#xA;<h3 id="why-are-all-the-elements-of-my-array-changed-in-python">Why are all the elements of my array changed in Python?</h3>&#xA;This happens because when Python creates the array, it is not creating 4 different arrays, but it creates only one and copies 4 times the reference to this memory space, so, any change we make is modifying the only array that exists and, as the 4 references point to that array, we see the change reflected in all the arrays.&#xA;<h2 id="how-to-prevent-this-error">How to prevent this error?</h2>&#xA;To prevent this error when creating a two-dimensional matrix.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">new_matrix = [[0]*4 for _ in range(4)]&#xA;new_matrix[0][1] = 3&#xA;# [[0, 3, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0]]&#xA;</code></pre></div>In the above code, a new array is created for each element in our list comprehension, ensuring that there are 4 individual arrays and that each change occurs only once in our two-dimensional array.&#xA;Now you know that, if in a two-dimensional matrix you are changing all the elements when you modify a single one, you must change the way you generated your matrix.&#xA;

The other day I was solving a kata in codewars , one of the steps of the problem needed a two-dimensional array, in more mundane words: an array of arrays. In Python it is super simple to create a two-dimensional array using the multiplication operator, as if it were numbers.&#xA;arr = [0]*5 #[0, 0, 0, 0, 0] If you have no idea what I&rsquo;m talking about, I have an excellent resource that can help you a lot: &ldquo;Inmersion en Python&rdquo;, totally free and in Spanish The wrong way to create arrays in Python Knowing how to create arrays using the multiplication operator, we could think of creating a two-dimensional array as follows:

Don't make this mistake using arrays in Python

You probably already know how to upload an image using a Django model, but what if we don&rsquo;t want to upload one but multiple images?&#xA;<h2 id="django-installation">Django installation</h2>&#xA;First we install Django using pipenv. We will also install Pillow since we will be dealing with images.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">pip install django Pillow&#xA;</code></pre></div>Next we will create a new project and enter the newly created folder.&#xA;If you don&rsquo;t know GNU/Linux commands I have a series of entries &#xA;&#xA;<a class="markdown-link" href="https://coffeebytes.dev/en/linux-basic-commands-grep-ls-cd-cat-cp-rm-scp/">with the most used GNU Linux commands</a>&#xA;&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">django-admin startproject yourproject&#xA;cd yourproject/&#xA;</code></pre></div>Next, let&rsquo;s create an application, and name it gallery.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">django-admin startapp gallery&#xA;</code></pre></div>Remember to install the new application we created in the settings.py file.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python"># settings.py&#xA;INSTALLED_APPS = [&#xA; # ...,&#xA; &#39;gallery&#39;&#xA;]&#xA;</code></pre></div><h2 id="creation-of-a-model">Creation of a model</h2>&#xA;Inside our application named gallery, we are going to create a model with an Image field.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">from django.db import models&#xA;&#xA;class gallery(models.Model):&#xA; image = models.ImageField()&#xA;</code></pre></div>Let&rsquo;s run the migrations so that the changes in our application are reflected in the database.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">python manage.py migrate&#xA;</code></pre></div><h2 id="adding-templates">Adding templates</h2>&#xA;Next, let&rsquo;s create a folder called templates to host our template with the form.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash">mkdir templates&#xA;cd templates&#xA;touch index.html&#xA;</code></pre></div>Let&rsquo;s add the templates location to the TEMPLATES configuration of our configuration file; settings.py.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python"># settings.py&#xA;TEMPLATES = [&#xA; {&#xA; &#39;BACKEND&#39;: &#39;django.template.backends.django.DjangoTemplates&#39;,&#xA; &#39;DIRS&#39;: [&#39;templates&#39;],&#xA; &#39;APP_DIRS&#39;: True,&#xA; &#39;OPTIONS&#39;: {&#xA; &#39;context_processors&#39;: [&#xA; &#39;django.template.context_processors.debug&#39;,&#xA; &#39;django.template.context_processors.request&#39;,&#xA; &#39;django.contrib.auth.context_processors.auth&#39;,&#xA; &#39;django.contrib.messages.context_processors.messages&#39;,&#xA; ],&#xA; },&#xA; },&#xA;]&#xA;</code></pre></div><h2 id="a-form-to-upload-multiple-images-in-django">A form to upload multiple images in Django</h2>&#xA;To make our input accept multiple images we add the multiple attribute to our input field.&#xA;Remember to add the POST method and the {% csrf_token %} tag so that your form is protected.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-html" data-lang="html">&lt;!DOCTYPE html&gt;&#xA;&lt;html lang=&#34;en&#34;&gt;&#xA;&lt;head&gt;&#xA; &lt;meta charset=&#34;UTF-8&#34;&gt;&#xA; &lt;meta name=&#34;viewport&#34; content=&#34;width=device-width, initial-scale=1.0&#34;&gt;&#xA; &lt;title&gt;Document&lt;/title&gt;&#xA;&lt;/head&gt;&#xA;&lt;body&gt;&#xA; &lt;form method=&#34;POST&#34; enctype=&#34;multipart/form-data&#34;&gt;&#xA; {% csrf_token %}&#xA; &lt;input type=&#34;file&#34; name=&#34;images&#34; multiple&gt;&#xA; &lt;button type=&#34;submit&#34;&gt;Send&lt;/button&gt;&#xA;&lt;/form&gt; &#xA;&lt;/body&gt;&#xA;&lt;/html&gt;&#xA;</code></pre></div><h2 id="creating-a-view-uploading-multiple-images-in-django">Creating a view uploading multiple images in Django</h2>&#xA;Now in our gallery application, let&rsquo;s modify the views file to create the view that will handle our image upload.&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python">from django.http import JsonResponse&#xA;from django.shortcuts import render&#xA;from .models import gallery&#xA;&#xA;def handleMultipleImagesUpload(request):&#xA; if request.method == &#34;POST&#34;:&#xA; images = request.FILES.getlist(&#39;images&#39;)&#xA;&#xA; for image in images:&#xA; gallery.objects.create(image = image)&#xA;&#xA; uploaded_images = gallery.objects.all()&#xA; return JsonResponse({&#34;images&#34;: [{&#34;url&#34;: image.image.url} for image in uploaded_images]})&#xA; return render(request, &#34;index.html&#34;)&#xA;</code></pre></div>If we make a POST request to this view we will get the list of images we uploaded, then we will create a new object for each image we uploaded and return the list of images with their respective url as a JSON response. Otherwise we will render the form and return it.&#xA;With the view already created, just add the url to our urls.py file in our project folder.&#xA;<h2 id="adding-the-url">Adding the url</h2>&#xA;To facilitate the process we will import the view directly and assign it to the upload/ url&#xA;<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-python" data-lang="python"># urls.py&#xA;from django.contrib import admin&#xA;from django.urls import path&#xA;from gallery.views import handleMultipleImagesUpload&#xA;&#xA;urlpatterns = [&#xA; path(&#39;upload/&#39;, handleMultipleImagesUpload, name=&#34;home&#34;),&#xA; path(&#39;admin/&#39;, admin.site.urls),&#xA;]&#xA;</code></pre></div>If we now access the upload/ address we will see our upload button and we will be able to upload multiple images.&#xA;<a href="images/subida-multiple-de-imagenes.gif" aria-label="multiple-image-upload in django">&#xA;&#xA; <img class="md-image" width="735" height="420" loading="lazy" src="images/subida-multiple-de-imagenes.gif" alt="multiple-image-upload in django"/>&#xA;&#xA;</a>&#xA;If the upload was successful we will get as a response a JSON with the addresses of the images we just uploaded.&#xA;Here we use Django to render the form. However, as you may know, instead of rendering a form, you can constrain the function to act as an API. And then consume it by making a POST request with javascript.&#xA;Finally, if you want to go deeper into the functionality of Django&rsquo;s ImageField fields, check out &#xA;&#xA;<a class="markdown-link" href="https://docs.djangoproject.com/en/3.1/ref/models/fields/" rel="noopener" target="_blank">the official documentation</a>&#xA;&#xA;

You probably already know how to upload an image using a Django model, but what if we don&rsquo;t want to upload one but multiple images?&#xA;Django installation First we install Django using pipenv. We will also install Pillow since we will be dealing with images.&#xA;pip install django Pillow Next we will create a new project and enter the newly created folder.&#xA;If you don&rsquo;t know GNU/Linux commands I have a series of entries with the most used GNU Linux commands django-admin startproject yourproject cd yourproject/ Next, let&rsquo;s create an application, and name it gallery.

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