Django Streaming HTTP Response from RESTful API

Question

I have a Django app that needs to interact with a database of medical images. They have a RESTful API that returns a stream of bytes, which I am writing to a HttpStreamingResponse. This is working, but the issue is that it is very slow. Most files I am downloading are around 100mb, and it usually takes around 15-20 seconds before the download even begins. Does anyone have insight into how to speed up this process and start the download faster?

Here is my code:

# Make api call
response = requests.get(url, cookies=dict(JSESSIONID=self.session_id))
# write bytes to Http Response 
http = StreamingHttpResponse(io.BytesIO(response.content), content_type='application/zip')

http['Content-Disposition'] = 'attachment; filename="%s.zip"' % patient_id
return http

Kevin Lee · Accepted Answer · 2018-09-18 01:12:19Z

2

You are downloading the full response to your server before passing on the information.

You should just forward the response from the API call using the following:

res = FROM API CALL
response = HttpResponse(ContentFile(res.content), 'application/zip')
response['Content-Disposition'] = 'attachment; filename={}.zip'.format(patient_id)
response['Content-Length'] = res.headers.get('Content-Length')
response['Content-Transfer-Encoding'] = res.headers.get('Content-Transfer-Encoding')
response['Content-Type'] = res.headers.get('Content-Type')
return response

Make sure you copy over any important headers.

Edit: Since this is the only proposed solution, I'm editing to include the solution from John's comment in a more readable format:

# Make api call 
response = requests.get(url, cookies=dict(JSESSIONID=self.session_id), stream=True) 
# write bytes to Http Response 
http = StreamingHttpResponse(response.iter_content(8096), content_type='application/zip') 
http['Content-Disposition'] = 'attachment; filename="%s.zip"' % patient_id 
return http

edited Sep 18, 2018 at 1:12

answered Sep 5, 2018 at 1:26

Kevin Lee

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1 Comment

hootiehoo Over a year ago

Thanks Kevin, I had the same issue with your block of code but just solved it by adding stream=True to response. Here is the solution for others with the same issue:

# Make api call response = requests.get(url, cookies=dict(JSESSIONID=self.session_id), stream=True) # write bytes to Http Response  http = StreamingHttpResponse(response.iter_content(8096), content_type='application/zip')  http['Content-Disposition'] = 'attachment; filename="%s.zip"' % patient_id return http

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