PermissionDeniedMiddleware for Django 1.2.x

middleware.py

"""
Improve PermissionDenied/HttpResponseForbidden handling in Django 1.2.

At some point, Django added better handling for PermissionDenied
and HttpResponseForbidden, including a handler403 on the ROOT_URLCONF, and,
I think, the ability to fall back to a generic 403.html.

But Django 1.2 didn't have that, as far as I know. So this middleware adds
it for Django 1.2 projects.

"""


from django import template
from django.conf import settings
from django.http import HttpResponseForbidden

if getattr(settings, 'ROOT_URLCONF'):
    package, _, module = settings.ROOT_URLCONF.rpartition('.')
    urls = __import__(module, fromlist=[package])
else:
    urls = None


class PermissionDeniedMiddleware(object):
    """Add a 403 handler."""
    def process_response(self, request, response):
        if isinstance(response, HttpResponseForbidden):
            if request.user.is_authenticated():
                if urls and hasattr(urls, 'handler403'):
                    module, _, fn = urls.handler403.rpartition('.')
                    try:
                        view  = __import__(fn, fromlist=[module])
                    except ImportError:
                        return response
                    return view(request)
                try:
                    t = template.loader.get_template('403.html')
                except template.TemplateDoesNotExist:
                    return response  # No better idea. Reraise?
                c = template.RequestContext(request)
                return HttpResponseForbidden(t.render(c))
        return response