Python, Flask: How to set response header for all responses

Question

I want to set all of my http headers responses to something like this:

response.headers["X-Frame-Options"] = "SAMEORIGIN" 

I checked this question, but it only changes the header for one specific controller. I want to change all of my headers maybe in "before_request" function similar to the following logic. How can I do that?

@app.before_request def before_request():     # response.headers["X-Frame-Options"] = "SAMEORIGIN" 

Answer 1

Set the header in a @app.after_request() hook, at which point you have a response object to set the header on:

@app.after_request def apply_caching(response):     response.headers["X-Frame-Options"] = "SAMEORIGIN"     return response 

The flask.request context is still available when this hook runs, so you can still vary the response based on the request at this time.

Answer 2

The @app.after_request() hook was not adequate for my use case.

My use case is as follows: I have a google cloud function, and I want to set the CORS headers for all responses. There are possibly multiple responses, as I have to validate the input and return if there are issues with it, I have to process data and possibly return early if something fails etc. So I've created a helper function as follows:

# Helper function to return a response with status code and CORS headers def prepare_response(res_object, status_code):     response = flask.jsonify(res_object)     response.headers.set('Access-Control-Allow-Origin', '*')     response.headers.set('Access-Control-Allow-Methods', 'GET, POST')     return response, status_code 

Thus, when I want to return a response (always with CORS headers), I can now call this function and I do not duplicate the response.headers setup necessary to enable CORS.