How to Handle PUT Request in Flask: Simple Guide

To handle a PUT request in Flask, define a route with methods=['PUT'] and write a function to process the request data. Use request.get_json() to access JSON data sent in the PUT request body.

Why This Happens

Developers often forget to specify methods=['PUT'] in the route decorator, so Flask treats the route as only accepting GET requests. This causes a 405 Method Not Allowed error when sending a PUT request.

python

from flask import Flask, request

app = Flask(__name__)

@app.route('/update')
def update():
    data = request.get_json()
    return {'message': 'Data received', 'data': data}

if __name__ == '__main__':
    app.run()

Output

Method Not Allowed (405) error when sending a PUT request to /update

The Fix

Add methods=['PUT'] to the route decorator to tell Flask this route accepts PUT requests. Then use request.get_json() to read the JSON data sent in the request body.

python

from flask import Flask, request

app = Flask(__name__)

@app.route('/update', methods=['PUT'])
def update():
    data = request.get_json()
    return {'message': 'Data updated successfully', 'data': data}

if __name__ == '__main__':
    app.run()

Output

{"message": "Data updated successfully", "data": {"name": "Alice", "age": 30}}

Prevention

Always specify the HTTP methods your route should accept using the methods parameter in the route decorator. Use tools like Postman or curl to test your endpoints with different HTTP methods. Enable Flask debugging mode to see detailed errors during development.

Follow REST principles by using PUT for updating resources and ensure your client sends the correct Content-Type header (usually application/json).

Related Errors

405 Method Not Allowed: Happens when the route does not accept the HTTP method used. Fix by adding the method to methods.

400 Bad Request: Happens if the JSON data is missing or malformed. Fix by validating input and checking request.is_json.

Key Takeaways

Specify methods=['PUT'] in your Flask route to handle PUT requests.

Use request.get_json() to access JSON data sent in the PUT request body.

Test your API endpoints with tools like Postman to verify HTTP method handling.

Enable Flask debug mode during development to catch method errors quickly.

Validate incoming data to avoid bad request errors.