Using Flask, how do I modify the Cache-Control header for ALL output?

flask, http, python

Solution

Use the `response.cache_control` object; this is a `ResponseCacheControl()` instance letting you set various cache attributes directly. Moreover, it'll make sure not to add duplicate headers if there is one there already.

@app.after_request
def add_header(response):
    response.cache_control.max_age = 300
    return response

Problem

I tried using this ``` @app.after_request def add_header(response): response.headers['Cache-Control'] = 'max-age=300' return response ``` But this causes a duplicate Cache-Control header to appear. I only want max-age=300, NOT the max-age=1209600 line! ``` $ curl -I http://my.url.here/ HTTP/1.1 200 OK Date: Wed, 16 Apr 2014 14:24:22 GMT Server: Apache Cache-Control: max-age=300 Content-Length: 107993 Cache-Control: max-age=1209600 Expires: Wed, 30 Apr 2014 14:24:22 GMT Content-Type: text/html; charset=utf-8 ```

Original source