pythoncachingflask

Disabling caching in Flask


I have some caching issues. I'm running very small web-application which reads one frame, saves it to the disk and then shows it in browsers window.

I know, it is probably not the best solution, but every time I save this read frame with the same name and therefor any browser will cache it.

I tried to use html meta-tags - no success:

<meta http-equiv="Cache-Control" content="no-cache, no-store, must-revalidate" />
<meta http-equiv="Pragma" content="no-cache" />
<meta http-equiv="Expires" content="0" />

Also, I have tried this one (flask-specific):

resp.headers["Cache-Control"] = "no-cache, no-store, must-revalidate"
resp.headers["Pragma"] = "no-cache"
resp.headers["Expires"] = "0"

This is how I tried to modify resp headers:

r = make_response(render_template('video.html', video_info=video_info))

r.headers["Cache-Control"] = "no-cache, no-store, must-revalidate"
r.headers["Pragma"] = "no-cache"
r.headers["Expires"] = "0"

Still both Google Chrome and Safari do caching.

What might be the problem here?


Solution

  • OK,

    finally it worked with this:

    @app.after_request
    def add_header(r):
        """
        Add headers to both force latest IE rendering engine or Chrome Frame,
        and also to cache the rendered page for 10 minutes.
        """
        r.headers["Cache-Control"] = "no-cache, no-store, must-revalidate, public, max-age=0"
        r.headers["Pragma"] = "no-cache"
        r.headers["Expires"] = "0"
        return r
    

    If you add this, this function will called after each request done. Please,see here

    I would be happy, if anyone could explain me why this headers overwriting did not work from the page handler?

    Thank you.