id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
11122	views.static.serve does not work with if-modified-since header the third time a file is requested	Rob van der Linde	nobody	"This is a very strange bug, but I will try to explain.  I have a static file that has a 2006 last-modified date on it.  The first time this file is requested through django.views.static.serve, the browser will download the file fully and send a last-modified header with it, properly dating to 2006.  The second time this file is requested, the browser will send an if-modified-since request and the serve function detects this and only sends a HttpResponseNotModified so the browser won't re-download the file (this is fine so far and what I would expect).  The problem is when I try to request the file for a third time, it will re-download the file, although it shouldn't (this is with Firefox 3 at least).  I had a look with the web developer extension in Firefox and have found that the first time the file is sent, the last-modified date is 2006, but the third time the last-modified date is 2009. In fact, it is the date of the last request... not the date of the file... this is why it appears to be re-downloading the file the third time when it shouldn't.

I was able to fix this, by changing this part in /django/views/static.py (serve function, line 192):
{{{
    if not was_modified_since(request.META.get('HTTP_IF_MODIFIED_SINCE'),
                              statobj[stat.ST_MTIME], statobj[stat.ST_SIZE]):
        return HttpResponseNotModified()
}}}
To:
{{{
    if not was_modified_since(request.META.get('HTTP_IF_MODIFIED_SINCE'),
                              statobj[stat.ST_MTIME], statobj[stat.ST_SIZE]):
        response = HttpResponseNotModified()
        response[""Last-Modified""] = http_date(statobj[stat.ST_MTIME])
        return response
}}}
By sending the last-modified date of the file again with the HttpResponseNotModified response, the third time I request the file, it won't re-download the file again in Firefox and display the proper 2006 date in web developer extension, instead of 2009, effectively fixing the problem.  I don't know if this is a bug with Firefox or Django, however the small change to the code does fix it for me."		closed	Generic views	1.0		invalid			Unreviewed	0	0	0	0	0	0