Flask is a lightweight WSGI web application framework. It is designed to make getting started quick and easy, with the ability to scale up to complex applications.
Flask provides a really simple way to give feedback to a user with the flashing system. The flashing system basically makes it possible to record a message at the end of a request and access it on the next (and only the next) request.
Check out the Quickstart for an overview of what Flask can do, then dive into the docs to find out more. The tutorial only uses what’s provided by Flask and Python.
Then follow the installation instructions to set up a Python virtual environment and install Flask for your project. The tutorial will assume you’re working from the flask-tutorial directory from now on.
Flask can be used to serve Single-Page Applications (SPA) by placing static files produced by your frontend framework in a subfolder inside of your project. You will also need to create a catch-all endpoint that routes all requests to your SPA.
Flask parses incoming request data for you and gives you access to it through that global object. Internally Flask makes sure that you always get the correct data for the active thread if you are in a multithreaded environment.
In Flask you can easily implement the opening of database connections on demand and closing them when the context dies (usually at the end of the request). Here is a simple example of how you can use SQLite 3 with Flask:
Testing Flask Applications ¶ Flask provides utilities for testing an application. This documentation goes over techniques for working with different parts of the application in tests. We will use the pytest framework to set up and run our tests.
