Updated April 10, 2023
Definition of Flask Extensions
Flask extensions is defined as a set of utilities or in other words set of extra packages that are present in the Flask ecosystem that enables developers to add functionality in the Flask application being built. The set of utilities allows Flask to transform from a microframework to a full-fledged application tool for the development of web applications. The set has a wide range of code libraries and extensions that enables the Flask that allows the transformation of the Flask tool. Not only it enables easy development for web application developers, but it also helps in maintaining standardized features across the globe. For example, an authentication feature using the same extension will be standardized across all the places where the extension is used! In this article, we will review the extensions which are widely used in the development of web applications in Flask.
Explanation of each Flask Extensions
Before we start learning about individual flask extensions, let us understand some basic code practices and ground rules so that anyone re-using the project can do that with ease. When a new project is created, generally all the extensions and the libraries land upon the requirements.txt file. It is not only making sure that the extensions land up there, but also keeps a tab on the fact that the file is well maintained and active as well. These lists not only enable anyone new who will work on co-building the same application to know what needs to be there and what one needs to avoid but also help ourselves while developing a new application on what needs to be reused again so that half of the investigation on which package to use and finding the real worthy ones are out of scope. In the list below, most of the packages will be a part of a developer who builds Flask applications as a daily professional job. Now, without much further ado, let us go into understanding the individual extensions in depth. The chronological order is not indicative of the ranks and all the extensions mentioned are equally important.
This extension is one of the most popular WSGI-based servers for Python. This is like a modified copy of the popular unicorn server that exists in Ruby. The best feature about this extension is that this is very easy to configure, though the configuration options are enough for tweaking things to the need of the application. The extension is easy to pair with both personal and large-scale deployments. For a matter of trivia in the space of web application building, this server is used by Instagram and hence there is no question about the efficiency!
This extension enables developers with debugging options in the toolbar overlaid on the Flask applications. One can easily install it by executing the command pip install flask-debugtoolbar. The toolbar consists of HTTP headers, request variables, configuration settings, template renderings in a break down, queries from SQLAlchemy, and many more. Adding of custom output is also allowed. This toolbar not only enables developers to debug but also lays out the foundation to enable performance optimization.
pytest & pyest-cov
These are the Flask extensions that enable developers to test Flask applications. For running unit and integration tests, Pytest provides a great interface and also provides fixtures for the data too. With minimal boilerplate, pytest provides a lot of output from writing tests. In addition to pytest, pytest-cov is like an add-on that is used for reading out the test coverage.
This Flask extension enables developers to analyze the styling consistency and mistakes and this proves to be very beneficial during the development phase. The command is run against the code base, and as the commands execute warnings are thrown by the set of internal check this extension does, along with the errors which the extension encounters on the way. This is widely used for any open source projects so that there is consistency and uniformity in the style guides. Make sure to include this as a part of the test routines.
Flask-SQLAlchemy & psycopg2
Flask applications widely use relational databases and the widely used weapon of choice is PostgreSQL. The extension psycopg2 allows python to communicate with PostgreSQL and additionally Flask-SQLAlchemy uses SQLAlchemy in providing users with Object-relational mapping (ORM).
During migration of database, alembic is the obvious choice for anything related to SQLAlchemy. Setting a simple DB to migrate script using Alembic is just a few lines of code. This is more preferred extension in comparison to Flask-Migrate which more or less does the same job.
celery & Redis
For anything which needs the execution of background jobs, celery is undoubtedly the only choice backed by redis. Super battle-hardened; Celery uses Redis as a storage place with a key-value pair combination of the Celery jobs.
Flask-WTF & WTForms-Components
One building a Flask web application and doesn’t process forms doesn’t sound resonating. Flask-WTF and WTForms-components are the go-to extensions. Setting up validation rules, additional logic for processing the form, providing common field types, etc. as an example one would want to build a utility, where a component like Email-ID should be unique. Usage of WTForms-Components is perfect for the case!
An undoubted winner in case of building anything related to login in Flask application. We have an extensive article on Flask login from EduCBA, but one thing to highlight here is that this extension enables developers by taking on the scary parts like authentication, session management, cookies, etc. and for this extension, it is a simple game!
This extension enables developers with having capability to control traffic rates. This extension enables users to put business rules so that web traffic can be easily limited and managed.
In various Flask applications, one would need to use the feature of sending mail, and this is what is achieved by this extension which handles sending of SMTP-based mails. The mail server needs to be configured with credentials along with few other things like TLS and then we are all set to go!
In this article, we have widely used extensions in the Flask application. Though not an extensive list of all flask extensions, the ones mentioned here is something analogous to a small treasure that will be required for any of the web application that is built!
This is a guide to Flask Extensions. Here we discuss the definition, explanation of lists of Flask Extensions. You may also have a look at the following articles to learn more –