Question

I am trying to return a zip file in django http response, the code goes something like…

archive = shutil.make_archive('testfolder', 'zip', MEDIA_ROOT, 'testfolder')
response = HttpResponse(FileWrapper(open(archive)),
                           content_type=mimetypes.guess_type(archive)[0])
response['Content-Length'] = getsize(archive)
response['Content-Disposition'] = "attachment; filename=test %s.zip" % datetime.now()
return response

Now when this code is executed on ubuntu the resulting downloaded file opens without any issue, but when its executed on windows the file created does not open in winzip (gives error ‘Unsupported Zip Format’).

Is there something very obvious I am missing here? Isn’t python code supposed to be portable?

EDIT:

Thanks to J.F. Sebastian for his comment…

There was no problem in creating the archive, it was reading it back into the request. So, the solution is to change second line of my code from,

response = HttpResponse(FileWrapper(open(archive)),
                           content_type=mimetypes.guess_type(archive)[0])

to,

response = HttpResponse(FileWrapper(open(archive, 'rb')),  # notice extra 'rb'
                           content_type=mimetypes.guess_type(archive)[0])

checkout, my answer to this question for more details…

Answer 1

Thanks to J.F. Sebastian for his comment…

I’ll still write the solution here in detail…

There was no problem in creating the archive, it was reading it back into the request. So, the solution is to change second line of my code from,

response = HttpResponse(FileWrapper(open(archive)),
                           content_type=mimetypes.guess_type(archive)[0])

to,

response = HttpResponse(FileWrapper(open(archive, 'rb')),  # notice extra 'rb'
                           content_type=mimetypes.guess_type(archive)[0])

because apparently, hidden somewhere in python 2.3 documentation on open:

The most commonly-used values of mode are ‘r’ for reading, ‘w’ for
writing (truncating the file if it already exists), and ‘a’ for
appending (which on some Unix systems means that all writes append to
the end of the file regardless of the current seek position). If mode
is omitted, it defaults to ‘r’. The default is to use text mode, which
may convert ‘\n’ characters to a platform-specific representation on
writing and back on reading. Thus, when opening a binary file, you
should append ‘b’ to the mode value to open the file in binary mode,
which will improve portability. (Appending ‘b’ is useful even on
systems that don’t treat binary and text files differently, where it
serves as documentation.) See below for more possible values of mode.

So, in simple terms while reading binary files, using open(file, 'rb') increases portability of your code (it certainly did in this case)

Now, it extracts without troubles, on windows…