What IS Flask
Short introduction to Flask
Last updated
Was this helpful?
Short introduction to Flask
Last updated
Was this helpful?
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. Classified as a microframework, Flask is written in Python and 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.
Compared to his older brother , Flask provides a lightweight codebase and more freedom to the developer. This might be a good thing because you have more freedom in terms of app design and structure but at the same time, this freedom might inject problems when your application becomes complex.
Being a Python framework, Flask requires Python to run and expose his magic. Flask is compatible with Python2, Python3 (the recommended version).
Install Python
To get started working with Python3, you’ll need to have access to the Python interpreter (the console, and related tools and libraries). We can accomplish this in several ways:
Download the installer from the official page.
Use a package manager like yum, apt on Linux systems
Homebrew for MacOS users.
Build Python from sources, a method used by super-geeks.
To install Python on our windows workstation, a few simple steps should be followed:
Navigate to the official page, using a web browser
Select the installer that matches the OS (32b or 64b)
Execute the installer (using the default options, should be enough in most of the cases)
Test the installation by typing python --version
in a terminal
There is a very good chance your Linux distribution has Python installed already, but it probably won’t be the latest version, and it may be Python 2 instead of Python3. To check the installed versions, just type:
To install, you should first update your system with the yum
package manager:
Other useful links
To install Flask, we can use PIP
, the official Python package manager:
During Flask installation, other modules will be installed under-the-hood:
To code a super simple app with Flask we need to create a new file hello.py
and write a few lines of code:
Above lines, saved in hello.py
means:
Flask
is imported and become ready to be used
app
is an object constructed by Flask
library
app
object inherit all Flask magic
@app.route
is a decorator
that define a default route for our app
When the browser access our app, the message Hello, from Flask!
will be displayed.
How to start the app
To run the application you can either use the flask command or python’s -m
switch with Flask. Before starting the app, we should export the FLASK_APP
environment variable:
To effectively start the app, please type:
By default, Flask will start the app on port 5000 - http://localhost:5000
. By accessing this local address, we should see the message Hello, from Flask!
With this minimal example in mind, we can extend this app with more features. A possible list might be:
add more routes
add a database to save relevant information
add static assets to use a Bootstrap style, for instance
implement an authentication system
App Features
UI Kit: Black Dashboard (Free version) provided by Creative-Tim
Modular design with Blueprints
SQLite, PostgreSQL, SQLAlchemy ORM
Alembic (DB schema migrations)
Session-Based authentication (via **flask_login
App Links
If you still have issues set up your workstation for Python, feel free to join the server and ask for support.
- hosted by RealPython
- a complete guide for many OS: Fedora, MacOS, Ubuntu
implements WSGI, the standard Python interface between applications and servers.
is a template language that renders the pages your application serves.
comes with Jinja. It escapes untrusted input when rendering templates to avoid injection attacks.
securely signs data to ensure its integrity. This is used to protect Flask’s session cookie.
is a framework for writing command-line applications. It provides the flask command and allows adding custom management commands.
is a simple, open-source Flask starter coded with basic modules, database and deployment scripts for Docker, HEROKU and Gunicorn.
- Product page
- LIVE app