Django view for applying webassets bundles per file

urls.py

# prefix option in the bundle is set to '__assets__'

from django.views.generic.simple import redirect_to

urlpatterns = patterns('',
    url(r'^__assets__/static/(?P<url>.*\.css)$', 'views.filter_css'),
    url(r'^__assets__/static/(?P<url>.*\.less)$', 'views.filter_css'),
    (r'^__assets__/static/(?P<rest>.*)$', redirect_to, {'url': '/static/%(rest)s'} ),
)

views.py

from django.http import HttpResponse
from django.http import Http404
from django.contrib.staticfiles.finders import find

from django_assets.env import get_env
from django_assets import Bundle

import StringIO

def filter_css(request, url):

    filepath = find(url)

    if not filepath:
        raise Http404("'%s' could not be found" % filepath)

    env = get_env()

    our_bundle = [bundle for bundle in env if url in bundle.contents]

    if not our_bundle:
        try:
            file = open(filepath)
            try:
                data = file.read().decode('utf-8')
            finally:
                file.close()
            return HttpResponse(data, mimetype='text/css')
        except IOError:
            raise Http404("'%s' could not be opened" % filepath)

    b = Bundle(url, filters=our_bundle[0].filters, debug=our_bundle[0].debug, output=our_bundle[0].output)

    output = StringIO.StringIO()

    b.build(env=env, force=True, output=output)

    data = output.getvalue()
    output.close()

    return HttpResponse(data, mimetype='text/css')