Flask (web framework)
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|Initial release||April 1, 2010|
Flask is a micro web framework written in Python. It is classified as a microframework because it does not require particular tools or libraries. It has no database abstraction layer, form validation, or any other components where pre-existing third-party libraries provide common functions. However, Flask supports extensions that can add application features as if they were implemented in Flask itself. Extensions exist for object-relational mappers, form validation, upload handling, various open authentication technologies and several common framework related tools. Extensions are updated far more frequently than the core Flask program.
Flask was created by Armin Ronacher of Pocoo, an international group of Python enthusiasts formed in 2004. According to Ronacher, the idea was originally an April Fool's joke that was popular enough to make into a serious application.
Despite the lack of a major release, Flask has become popular among Python enthusiasts. As of mid 2016, it was the most popular Python web development framework on GitHub,[failed verification] and was voted the most popular framework in the Python Developers Survey 2018.
The microframework Flask is based on the Pocoo projects Werkzeug and Jinja2.
Werkzeug is a utility library for the Python programming language, in other words a toolkit for Web Server Gateway Interface (WSGI) applications, and is licensed under a BSD License. Werkzeug can realize software objects for request, response, and utility functions. It can be used to build a custom software framework on top of it and supports Python 2.6, 2.7 and 3.3.
Jinja, also by Ronacher, is a template engine for the Python programming language and is licensed under a BSD License. Similar to the Django web framework, it provides that templates are evaluated in a sandbox.
- Contains development server and debugger
- Integrated support for unit testing
- RESTful request dispatching
- Uses Jinja2 templating
- Support for secure cookies (client side sessions)
- 100% WSGI 1.0 compliant
- Extensive documentation
- Google App Engine compatibility
- Extensions available to enhance features desired
The following code shows a simple web application that displays "Hello World!" when visited:
from flask import Flask app = Flask(__name__) @app.route("/") def hello(): return "Hello World!" if __name__ == "__main__": app.run()
- "Flask Foreword".
- "Flask Extensions".
- What challenges has Pinterest encountered with Flask?
- Rachel Sanders: Developing Flask Extensions - PyCon 2014
- Community web page for Flask
- "Pocoo Team". Archived from the original on 2018-03-15.
- Ronacher, Armin. "Opening the Flask" (PDF). Archived from the original (PDF) on 2016-12-17. Retrieved 2011-09-30.
- Ronacher, Armin (3 April 2010). "April 1st Post Mortem". Armin Ronacher's Thoughts and Writings. Archived from the original on 2018-05-14. Retrieved 2015-07-25.
- "Denied: the next generation python micro-web-framework (April Fools page)". Archived from the original on 2011-09-04. Retrieved 2011-09-30.
- "History". Pocoo Team. Archived from the original on 2017-11-19.
- "Python libraries by GitHub stars".
- "Python Developers Survey 2018". www.jetbrains.com. 2018-11-01.
- Ronacher, Armin. "Werkzeug The Python WSGI Utility Library". palletsprojects.com. Retrieved 27 May 2018.