In this article, we will learn to install Flask-CORS which is a Python module and a Flask extension that supports and allows cross-origin resource sharing (CORS) through a simple decorator. Due to security concerns, cross-domain cookie submission is disabled by default. We will look at how to install Flask-Cors on the Linux operating system.
What is Python CORS?
When one domain requests a resource from another domain, this is referred to as cross-origin resource sharing or CORS. When a front-end and back-end are in distinct origins, this happens most commonly. Using JavaScript scripts, which share similar principles with the backend, the frontend communicates with the backend. Cross-origin AJAX is made possible with Flask CORS, which is only the Flask plugin for managing CORS.
What are Flask-Cors used for?
- It enables communication with resources housed in many domains.
- It’s a crucial protocol for enabling cross-domain queries when there is a justifiable need to do so.
Install the Flask-Cors package
Step 1: Run the below command in the terminal to install Python3 on your Linux OS:
sudo apt-get install python3
Step 2: Next, install the pip module, which is required for Python3 package installation and management. As a result, use the below command:
sudo apt install python3-pip
Step 3: Once the installation is complete, verify it by looking at the Python and pip versions:
python3 --version pip --version
The version number may differ, but it will look like this:
Step 4: Use the below command to install the Flask-Cors package:
pip install Flask-Cors
Step 5: Run the below command in the terminal to see if the Flask-Cors package has been successfully installed on your Linux Machine:
python3 -m pip show Flask-Cors
If the installation is successful, the following information would be visible on the terminal screen:
How to Enable CORS in the Flask
Method 1: To enable CORS for all domains on all routes, initialize the Flask-Cors extension with default parameters.
Python3
from flask import Flask from flask_cors import CORS app = Flask(__name__) CORS(app) @app.route("/") def welcome(): return "Hello world! Welcome by Kushal" |
Method 2: Simply add @cross_origin() below a call route to Flask’s @app. route(..) to allow CORS on a given route.
Python3
@app.route("/") @cross_origin() def helloWorld(): return "Hello world! Welcome by Kushal" |
Usage of Flask-Cors Package
This package exposes a Flask extension that enables CORS support by default on all routes, origins, and methods and provides a simple decorator for decorating Flask routes. To accept the default options and allow CORS on a given route, @cross origin() is to be added after a call to Flask’s @app.route(). Refer to the following function with different options to learn further about it.
Python
flask_cors.cross_origin( origins = '*', methods = ['GET', 'HEAD', 'POST', 'OPTIONS', 'PUT'], headers = None, supports_credentials = False, max_age = None, send_wildcard = True, always_send = True, automatic_options = False) |
