Streaming a CSV file in Django

Question

I am attempting to stream a csv file as an attachment download. The CSV files are getting to be 4MB in size or more, and I need a way for the user to actively download the f

Answer 1

The problem I was having was with the ConditionalGetMiddleware. I saw django-piston come up with a replacement middleware for the ConditionalGetMiddleware that allows streaming:

from django.middleware.http import ConditionalGetMiddleware

def compat_middleware_factory(klass):
    """
    Class wrapper that only executes `process_response`
    if `streaming` is not set on the `HttpResponse` object.
    Django has a bad habbit of looking at the content,
    which will prematurely exhaust the data source if we're
    using generators or buffers.
    """
    class compatwrapper(klass):
        def process_response(self, req, resp):
            if not hasattr(resp, 'streaming'):
                return klass.process_response(self, req, resp)
            return resp
    return compatwrapper

ConditionalMiddlewareCompatProxy = compat_middleware_factory(ConditionalGetMiddleware)

So then you will replace ConditionalGetMiddleware with your ConditionalMiddlewareCompatProxy middleware, and in your view (borrowed code from a clever answer to this question):

def csv_view(request):
    def data():
        for i in xrange(10):
            csvfile = StringIO.StringIO()
            csvwriter = csv.writer(csvfile)
            csvwriter.writerow([i,"a","b","c"])
            yield csvfile.getvalue()

    #create the reponse object with a csv mimetype
    response = HttpResponse(
        data(),
        mimetype='text/csv',
        )
    #Set the response as an attachment with a filename
    response['Content-Disposition'] = "attachment; filename=test.csv"
    response.streaming = True
    return response