Disabling caching in Flask [duplicate]

Question

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?

Answer 1

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"     r.headers["Pragma"] = "no-cache"     r.headers["Expires"] = "0"     r.headers['Cache-Control'] = 'public, max-age=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.

Answer 2

If you have always the same problem, that Flask didn't see the updates in JS and CSS files, that because by default, Flask has as max-age value 12 hours. You can set it to 0 to resolve the problem like this:

app = Flask(__name__) app.config['SEND_FILE_MAX_AGE_DEFAULT'] = 0 

Refer to its documentation for details.