Static serve failure since 1.4.18

[TheRealEckat]

With version 1.4.18 a change modified django.views.static.serve at line 65 for reading the file.
HttpResponse is called with the iter object, but this can't do anything with that.
From Django 1.5 the CompatibleStreamingHttpResponse is used at this point.

Reproducible by adding

if settings.DEBUG:
    urlpatterns += patterns('',
        url(r'^media/(?P<path>.*)$', 'django.views.static.serve', {
            'document_root': settings.MEDIA_ROOT,
        }),
   )

to the urls.py an call a file in that path.

The Response status is 200 and the content lenght is transmitted correctly.
In fact, only 0 bytes transferred.

A possible fix is, to change the line to

    response = HttpResponse(''.join(iter(lambda: f.read(STREAM_CHUNK_SIZE), '')), mimetype=mimetype)

[Tim Graham]

I can't reproduce this problem on Python 2.7; serving files seems to work just fine. What version of Python are you using? Are you using a browser to request the files or something else?

[Tim Graham]

Actually, it seems likely that this is caused by one of your middlewares consuming the iterator prematurely, see the ​1.5 release notes. We could document this caveat in the 1.4.18 release notes if it seems appropriate. Your proposed change would negate the benefit of the security fix.

[TheRealEckat]

Replying to timgraham:

I can't reproduce this problem on Python 2.7; serving files seems to work just fine. What version of Python are you using? Are you using a browser to request the files or something else?

I use python 2.7.
A colleague can reproduce this problem.

I located a potential problem with the middlewares, but I commented them one by one out.
After first middleware, the length od the response is always zero.
The first two one in my settings are custom middlewares, but the third is the django CsrfViewMiddleware. This middleware does the same, the response length is then zero.

Thanks for the hint with the documentation of django 1.5, I'll check it on monday.

[TheRealEckat]

UPDATE:

The problem is located in django.middleware.gzip.GZipMiddleware.

If I comment out the gzip middleware, the output is looking good.

[Benjamin Richter]

I can reproduce this.

Using the GZipMiddleware on 1.4.18 and the static.serve view results in all served files having empty content.

Curiously it works for serving static files via static files contrib app which uses said view as well.

In 1.5 GZipMiddleware was changed to check for Streaming response, same could be backported to 1.4 checking response content for GeneratorType.

[Benjamin Richter]

I opened Pull request 3987 with a fix for GZipMiddleware: ​https://github.com/django/django/pull/3987

I backported django.utils.text.compress_sequence and some of the newer GZipMiddleware code to 1.4 to check for response._base_content_is_iter before consuming response.content and added handling of iterables in responses.

This bug also happens when returning HTTPResponse(iter(...)) in any view.

Is this a feasible solution? Was it okay to recategorize this ticket?
This is my first django ticket I'm working on, so any feedback is very welcome.

[Tim Graham <timograham@…>]

In 1e39d0f6280abf34c7719db5e7ed1c333f5e5919:

[1.4.x] Fixed #24158 -- Allowed GZipMiddleware to work with streaming responses

Backport of django.utils.text.compress_sequence and fix for
django.middleware.gzip.GZipMiddleware when using iterators as
response.content.