"No data received" with custom handler403 in django - django

Question

When setting a simple handler403 for Django:
from django.conf.urls import url
from django.core.exceptions import PermissionDenied
from django.views.generic import TemplateView
class PermissionDeniedView(TemplateView):
template_name = '403.html'
handler403 = PermissionDeniedView.as_view()
def my_view(request):
raise PermissionDenied
urlpatterns = [
url(r'^$', my_view),
]
The browser does not receive any data (ERR_EMPTY_RESPONSE in chrome), and some errors appear on the log:
Traceback (most recent call last):
File "/usr/lib64/python2.7/wsgiref/handlers.py", line 86, in run
self.finish_response()
File "/usr/lib64/python2.7/wsgiref/handlers.py", line 127, in finish_response
for data in self.result:
File "/home/foo/.virtualenvs/bar/lib/python2.7/site-packages/django/template/response.py", line 171, in __iter__
raise ContentNotRenderedError('The response content must be '
ContentNotRenderedError: The response content must be rendered before it can be iterated over.
[20/May/2015 07:26:25]"GET / HTTP/1.1" 500 59
Traceback (most recent call last):
File "/usr/lib64/python2.7/SocketServer.py", line 599, in process_request_thread
self.finish_request(request, client_address)
File "/usr/lib64/python2.7/SocketServer.py", line 334, in finish_request
self.RequestHandlerClass(request, client_address, self)
File "/home/foo/.virtualenvs/bar/lib/python2.7/site-packages/django/core/servers/basehttp.py", line 102, in __init__
super(WSGIRequestHandler, self).__init__(*args, **kwargs)
File "/usr/lib64/python2.7/SocketServer.py", line 655, in __init__
self.handle()
File "/home/foo/.virtualenvs/bar/lib/python2.7/site-packages/django/core/servers/basehttp.py", line 182, in handle
handler.run(self.server.get_app())
File "/usr/lib64/python2.7/wsgiref/handlers.py", line 92, in run
self.close()
File "/usr/lib64/python2.7/wsgiref/simple_server.py", line 33, in close
self.status.split(' ',1)[0], self.bytes_sent
AttributeError: 'NoneType' object has no attribute 'split'

Answer 1

TemplateView returns a TemplateResponse instance with lazy content rendering by default, and is not suitable as is for handler403.
To force this view to render it's content, make sure .render() is called before returning the response:
class PermissionDeniedView(TemplateView):
template_name = '403.html'
def dispatch(self, request, *args, **kwargs):
response = super(PermissionDeniedView, self).dispatch(request, *args, **kwargs)
response.render()
return response