A common feature in web applications is to let users upload files to the server. The HTTP protocol documents the mechanism for a client to upload a file in RFC 1867, and our favorite web framework Flask fully supports it, but there are many implementation details that fall outside of the formal specification that are unclear for many developers. Things such as where to store uploaded files, how to use them afterwards, or how to protect the server against malicious file uploads generate a lot of confusion and uncertainty.

In this article I'm going to show you how to implement a robust file upload feature for your Flask server that is compatible with the standard file upload support in your web browser as well as the cool JavaScript-based upload widgets:

Sometimes it is useful to quickly access your Flask application running on localhost from another device or location for testing purposes. In this article I'll show you how to use the pyngrok package to provision a temporary public URL for your application that works from your phone or from anywhere in the world!

In this short video I comment on the benefits of using "trailing commas" when defining data structures in Python.

In this short video tutorial I demonstrate my Vim editor setup for working with Python applications.

Do you want to try this out? Download my .vimrc file! If your tagbar does not work, install Exuberant Ctags (use brew install ctags or sudo apt-get install ctags, or download from http://ctags.sourceforge.net/)

A question that I frequently get is how to start tracking database migrations with my Flask-Migrate extension when the project has an established database, making it impossible to delete everything and start over from scratch. In this article and companion video I'm going to show you how to set up Flask-Migrate with zero risk for your current database.

Welcome to the second part of my "React + Flask" series. In this episode we are going to deploy our project on a production server!

Have you missed the first part of this tutorial? You can find it here.

One of the questions I get asked more often lately is how to create a project that combines a React frontend with a Flask backend. Instead of giving vague answers I decided to write a tutorial about it, including a video in which I go through the steps to create a simple but fully functional React+Flask project.

This is the third part of my in-depth tutorial on Python decorators. In parts I and II I showed you how to create some useful decorators, but to keep things simple none of the decorator examples you've seen so far accept any arguments. In this installment you will learn how to write decorators that take custom arguments, like any normal Python function.

In this video I discuss a little MicroPython based project that I implemented in my home to improve the efficiency of the heating controller.

Welcome to the second part of my Python decorator series. In the first part I showed you the most basic style of decorators, which are used to register functions as handlers or callbacks for events. In this part I'm going to show you more interesting decorators that alter or complement the behavior of the decorated function.