Python Flask Intentional Empty Response

python flask response
RukTech picture RukTech · Jun 18, 2014 · Viewed 49.3k times · Source

Is there a way to return a response (from make_response() object or similar) with certain properties so that it doesn't render the page again and doesn't do anything else either. I am trying to run a code on the server without generating any output

A simple 'return None' produces:

ValueError: View function did not return a response

This should be possible because the following only downloads a file and doesn't render the template: 

myString = "First line of a document"
response = make_response(myString)
response.headers["Content-Disposition"] = "attachment; filename=myFile.txt"
return response

Answer

Martijn Pieters picture Martijn Pieters · Jun 18, 2014

You are responding to a request, your HTTP server must return something. The HTTP 'empty response' response is 204 No Content:

return ('', 204)

Note that returning a file to the browser is not an empty response, just different from a HTML response.

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