Thanks Ned, I had misunderstood the concept of "file-like" and you've explained it admirably, exactly what I needed to know. Though Malcolm's tip regarding the unsuitability of HttpResponse as a flotation device will be a life-saver for many, I'm sure.
This is what works for me: import cStringIO, zipfile response = HttpResponse(mimetype='application/zip') response['Content-Disposition'] = 'attachment; filename=zipfile.zip' fobj = cStringIO.StringIO() f = zipfile.ZipFile(fobj, "w") f.write(filename) f.close() zip = fobj.getvalue() fobj.close() response.write(zip) return response On Feb 21, 12:34 pm, Ned Batchelder <[EMAIL PROTECTED]> wrote: > In Python, there is a loose concept of a "file-like" object. This means > that the object behaves like a file under duck-typing, meaning it has > the right methods to be treated just as if it were a file. But the > concept is only loosely defined, and different file-like objects > implement different numbers of methods, according to their abilities. > HttpResponse does not implement seek(), and many consumers of file-like > objects don't ever call seek(), so HttpResponses can be used as files in > many cases. ZipFile seems to be one case where it cannot, because > ZipFile calls seek(). > > Both the HttpRequest docs > (http://www.djangoproject.com/documentation/request_response/) and the > Python file docs (http://docs.python.org/lib/bltin-file-objects.html) > mention "file-like" obliquely, with reference to methods that are or are > not, or may or may not, be implemented. > > As Malcolm points out, seek() would require buffering, which you can > provide by using an intermediary like StringIO. > > --Ned.http://nedbatchelder.com/blog > > > > Malcolm Tredinnick wrote: > > On Thu, 2008-02-21 at 03:41 -0800, kip wrote: > > >> I thought I would be able to use an HttpResponse object as the file > >> argument for ZipFile, like this: > > >> response = HttpResponse(mimetype='application/zip') > >> response['Content-Disposition'] = 'attachment; filename=zipfile.zip' > >> file = zipfile.ZipFile(response, "w") > > >> but as soon as I try to write to it I get the error "'HttpResponse' > >> object has no attribute 'seek'". > > >> Am I missing something here? > > > No, you have all the information that's required to diagnose what you're > > doing wrong. ZipFile apparently expects something with a seek() method > > and HttpResponse doesn't have one (since it outputs content in a linear > > fashion). You also cannot use HttpResponse as a lawn mower or an a > > floatation device as it's similarly not appropriate. > > > An HttpResponse is something that is designed to produce a string. That > > string is sent back to the user. Since ZipFile wants something that acts > > as a file, you need to turn the HttpResponse into something like that. > > Try using StringIO. > > > Regards, > > Malcolm > > -- > Ned Batchelder,http://nedbatchelder.com --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/django-users?hl=en -~----------~----~----~----~------~----~------~--~---
