Optimizing Slow SQL Queries

Most database problems go unnoticed during development, because we tend to code our applications using small datasets. It is when the application has been on production for some time that database performance issues start to appear, causing parts of the application to become slower and slower as the database continues to grow.

How do you debug and identify this type of problems? In this article I'm going to show you how to fix the most common database performance problems, which are those that are caused by improper indexing. Examples for Postgres, MySQL and SQLite are included!

This article was voted by my supporters on Patreon. Would you like to support my work, and as a thank you be able to vote on my future articles and have access to a chat room where I hang out and answer questions? Become a Patron!



How to Write Unit Tests in Python, Part 3: Web Applications

This is the third part in my series about unit testing Python applications. In this article I'm going to show you some of the techniques I use when I work with Python web applications. For the examples in this article I will be using the Flask framework (I know, what a surprise!), but the concepts I'll show you are universal and can be applied to other frameworks as well.

While this is the first article in the series that covers web applications, I will be applying many of the ideas and solutions I shared in the first and second parts, so be sure to check those out first, even if you are only interested in web applications.



Flask Mega-Tutorial Update: Flask 2.0 and more!

I'm excited to share that I've completed a revision of the Flask Mega-Tutorial to keep it in line with new releases of Flask, Python and third-party dependencies.

Flask Mega-Tutorial

To celebrate this update, you can purchase the paid version of this course with a $10 USD discount (this offer is valid through the rest of July 2021). If you are interested in this offer, use the FLASK2 promotional code at checkout, or click here to go directly to the order page with the coupon added. Thank you!



Beautiful Interactive Tables for your Flask Templates

Rendering a table with data in a Flask template is a relatively simple task when the table is short, but can be incredibly hard for larger tables that require features such as sorting, pagination and searching. In this article I'm going to show you how to integrate the dataTables.js library in your templates, which will allow you to create fully featured tables with ease!



How to Dockerize a React + Flask Project

This is the fourth article in my series about working with a combined Flask and React project. In this part I'm going to cover how to deploy the application in Docker containers.



Dynamically Update Your Flask Web Pages Using Turbo-Flask

How can you update a part of a web page dynamically, without the user having to hit the refresh button on the browser?

This is a question that is frequently asked on the Internet. If you have some knowledge of JavaScript this is relatively easy to do, more so if you use a front end web framework such as React or Vue. But what if you have a standard web application written in Flask and Jinja templates?

In this article I'm going to introduce you to my Turbo-Flask extension, which will allow your Flask application to easily push asynchronous page updates to the browser, without having to write any JavaScript code. In the screenshot below, note how the CPU load numbers update without the user doing anything.

Turbo-Flask Demo Application



How to Write Unit Tests in Python, Part 2: Game of Life

This is the second part of my series on unit testing Python applications. In this article I will introduce you to Conway's Game of Life, an interesting simulation that plays animated patterns on a grid.

Game of Life

My implementation of this game has an engine part, where the data structures and algorithm of the simulation are implemented, and a graphical user interface (GUI) part. In this article I will focus on testing the engine (testing GUIs will be covered in a future article).

Testing this code will present us with a few new challenges. In this article you will learn about the following topics:

  • Test parametrization
  • Building test matrices
  • Basic mocking
  • Testing Python exceptions



How to Write Unit Tests in Python, Part 1: Fizz Buzz

Today I'm starting a new series of articles about a topic that does not get a lot of coverage: how to write Python unit tests. Unlike other testing tutorials, I'm going to focus on testing techniques more than on the testing tools themselves. The idea is that in each part of this series I will look at a particular piece of code and discuss the challenges it presents from a testing point of view and how to address them.

In this first part I'm going to introduce the testing set up that I use in my projects, which is based on pytest. Then I will show you how to write unit tests for an implementation of the popular fizz buzz game that is frequently the subject of coding interview exercises.



Learn Socket.IO with Python and JavaScript in 90 Minutes!

The video below contains a complete 90 minute Socket.IO course using Python and JavaScript.

This is the list of chapters, each with a link to the code for each part of the tutorial:



Learn React in 90 Minutes!

Below you can watch my complete "Quick React Tutorial" video series. The entire seven-part series runs for about 93 minutes and will give you a fairly complete overview of the core features of the React framework.

Below you can see the list of parts in the series, each with a link to the code for that part of the tutorial: