serving files/iterated content with setting.USE_ETAGS = True

[pcicman]

It seems there's a bug in django.core.servers.basehttp.FileWrapper. FileWraper should do seek(0) before new interation.
Problem comes only with using Etags and this line (in django.middleware.common.CommonMiddleware):

etag = md5.new(response.content).hexdigest()

this calls code in HttpResponse object:

def _get_content(self):
        if self.has_header('Content-Encoding'):
            return ''.join(self._container)
        return smart_str(''.join(self._container), self._charset)

and join iterates over FileWrapper object:

def next(self):
        data = self.filelike.read(self.blksize)
        if data:
            return data
        raise StopIteration

but there's no return back to file begining. md5 Makes first iteration, and next iteration is called when response gets converted to string and set back to client.

Solution can probably be:

def next(self):
        data = self.filelike.read(self.blksize)
        if data:
            return data
            self.filelike.seek(0)
        raise StopIteration

Better solution

Add some temporary cache variable to HttpResponse object, so content gets iterated only once (i think this can be much more faster solution, shorter exec time).
In this case there's no seek(0) required.

[pcicman]

Wrong indentation used in solution :S

def next(self):
        data = self.filelike.read(self.blksize)
        if data:
            return data
        self.filelike.seek(0)
        raise StopIteration

[Thomas Güttler]

I understand this problem. I wrote a patch which checks first, if
the filelike object has a seek method.

Is FileWrapper documented somewhere? It is the first time I heard of it.

[Jim Garrison]

See bug #6527, which has a patch for iterating only once. In fact, it may make sense to mark this bug as a duplicate of that one.

[Aymeric Augustin]

Change UI/UX from NULL to False.

[Aymeric Augustin]

This is a duplicate of #6027.