Question

Using pdftk I generate some dynamic temporary pdf files, which then Django serves to the user.

On a desktop, it works fine – the pdf file opens which then user can save, however on my android phone in all browsers (maybe the same on iOS but don’t have and iOS device so can’t test), the pdf does not download successfully. It starts the download but then always fails and I can’t figure out why.

The following is a snippet of the view and the function which generates the pdf binary data:

def get_pdf():
    fdf = {...}
    t1 = tempfile.NamedTemporaryFile(delete=False)
    t2 = tempfile.NamedTemporaryFile(delete=False)
    t1.file.write(fdf)

    # close temp files for pdftk to work properly
    t1.close()
    t2.close()

    p = Popen('pdftk %s fill_form %s output %s flatten' %
              ('original.pdf', t1.name, t2.name), shell=True)
    p.wait()

    with open(t2.name, 'rb') as fid:
        data = fid.read()

    # delete t1 and t2 since they are temp files

    # at this point the data is the binary of the pdf
    return data


def get_pdf(request):
    pdf = get_pdf()

    response = HttpResponse(pdf, mimetype='application/pdf')
    response['Content-Disposition'] = 'filename=foofile.pdf'
    return response

Any ideas as to why this might be happening?

Answer 1

As per @Pascal comment, I added Content-Length and the downloads now work on mobile devices.

However it was not being downloaded with the filename I assign it in the view. Adding attachment fixes this but I don’t want the attachment to be present for desktop browsers. Hence the following is my final solution which works.

# I am using the decorator from http://code.google.com/p/minidetector/
@detect_mobile
def event_pdf(request, event_id, variant_id):
    pdf = get_pdf()

    response = HttpResponse(pdf, mimetype='application/pdf')
    response['Content-Disposition'] = '%sfilename=foofile.pdf' %
        request.mobile and 'attachment; ' or ''
    response['Content-Length'] = len(pdf)
    return response