How to Enable CORS in Flask: A Step-by-Step Guide

How to Enable CORS in Flask

Cross-Origin Resource Sharing (CORS) allows web applications to make requests to servers on different origins (domains, ports, or protocols) than the one on which they were originally loaded. When a client makes a cross-origin request, the server can decide whether to allow the request or not by setting the 'Access-Control-Allow-Origin' header.

To enable CORS in Flask, you can use the 'flask-cors' extension. This extension provides a simple and consistent way to configure CORS for your Flask application.

To install 'flask-cors', use the following command:

pip install -U flask-cors

Once you have installed 'flask-cors', you can configure it for your Flask application by adding the following code to your application:

<code class="python">from flask import Flask
from flask_cors import CORS

app = Flask(__name__)
cors = CORS(app)
app.config['CORS_HEADERS'] = 'Content-Type'

@app.route("/")
@cross_origin()
def helloWorld():
  return "Hello, cross-origin-world!"</code>

The 'CORS_HEADERS' configuration option specifies the allowed request headers. In this example, it allows the 'Content-Type' header, which is the default header used when sending a POST request.

The '@cross_origin()' decorator specifies that the function should allow cross-origin requests. It can be used on individual routes or on the entire application.

By following these steps, you can enable CORS in your Flask application and allow cross-origin requests from other domains.

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