Django rest framework error on empty view: the response content must be rendered before it can be iterated over

Question

I'm having a hard time finding the cause of this. I have a heartbeat view with token authentication, it just returns status=200 and I'm getting the response content must be rendered before it can be iterated over error.

It's related to token authentication but for the life of me, I can't figure it out.

urlpatterns = [
    path('heartbeat/', views.HeartbeatView.as_view(), name='heartbeat')]


class TokenAuthentication(authentication.BaseAuthentication):
    def authenticate(self, request):
        auth_token = request.META.get('HTTP_AUTHTOKEN')
        if not auth_token:
            return Response('No token', status=450)
        try:
            auth_token_inst = AuthToken.objects.select_related('user').get(token=auth_token)
            if not auth_token_inst:
                return Response('Not a valid token', status=451)
            if auth_token_inst.is_active is False:
                return Response('Expired token', status=452)
            user = auth_token_inst.user
            auth_token_inst.ExtendExpireDate()
        except AuthToken.DoesNotExist:
            return Response('No token', status=450)

        return (user, None)

class HeartbeatView(APIView):
    authentication_classes = (TokenAuthentication,)

    def get(self, request):
        """
        Update token with heartbeat
        """
        return HttpResponse(status=200)

[15/Jul/2019 07:10:31] ERROR [django.request:228] Internal Server Error: /heartbeat/ Traceback (most recent call last): File "/home/ubuntu/virtenv/lib/python3.5/site-packages/django/core/handlers/exception.py", line 34, in inner response = get_response(request) File "/home/ubuntu/virtenv/lib/python3.5/site-packages/django/core/handlers/base.py", line 115, in _get_response response = self.process_exception_by_middleware(e, request) File "/home/ubuntu/virtenv/lib/python3.5/site-packages/django/core/handlers/base.py", line 113, in _get_response response = wrapped_callback(request, *callback_args, **callback_kwargs) File "/home/ubuntu/virtenv/lib/python3.5/site-packages/django/views/decorators/csrf.py", line 54, in wrapped_view return view_func(*args, **kwargs) File "/home/ubuntu/virtenv/lib/python3.5/site-packages/django/views/generic/base.py", line 71, in view return self.dispatch(request, *args, **kwargs) File "/home/ubuntu/virtenv/lib/python3.5/site-packages/rest_framework/views.py", line 495, in dispatch response = self.handle_exception(exc) File "/home/ubuntu/virtenv/lib/python3.5/site-packages/rest_framework/views.py", line 455, in handle_exception self.raise_uncaught_exception(exc) File "/home/ubuntu/virtenv/lib/python3.5/site-packages/rest_framework/views.py", line 483, in dispatch self.initial(request, *args, **kwargs) File "/home/ubuntu/virtenv/lib/python3.5/site-packages/sentry_sdk/integrations/django/init.py", line 264, in sentry_patched_drf_initial return old_drf_initial(self, request, *args, **kwargs) File "/home/ubuntu/virtenv/lib/python3.5/site-packages/rest_framework/views.py", line 400, in initial self.perform_authentication(request) File "/home/ubuntu/virtenv/lib/python3.5/site-packages/rest_framework/views.py", line 326, in perform_authentication request.user File "/home/ubuntu/virtenv/lib/python3.5/site-packages/rest_framework/request.py", line 223, in user self._authenticate() File "/home/ubuntu/virtenv/lib/python3.5/site-packages/rest_framework/request.py", line 383, in _authenticate self.user, self.auth = user_auth_tuple File "/home/ubuntu/virtenv/lib/python3.5/site-packages/django/template/response.py", line 120, in iter 'The response content must be rendered before it can be iterated over.' django.template.response.ContentNotRenderedError: The response content must be rendered before it can be iterated over.

Does it work if you return HttpResponse('', status=200)?

Dov Rine
– Dov Rine

2019-07-15 08:34:58 +00:00
Commented Jul 15, 2019 at 8:34 — Dov Rine
– Dov Rine, Commented Jul 15, 2019 at 8:34
Also, is this django.http.HttpResponse?

Dov Rine
– Dov Rine

2019-07-15 08:35:45 +00:00
Commented Jul 15, 2019 at 8:35 — Dov Rine
– Dov Rine, Commented Jul 15, 2019 at 8:35
What @KhashayarGhamati said. ;)

Dov Rine
– Dov Rine

2019-07-15 08:36:56 +00:00
Commented Jul 15, 2019 at 8:36 — Dov Rine
– Dov Rine, Commented Jul 15, 2019 at 8:36

Carl · Accepted Answer · 2019-07-15 09:20:22Z

1

I've discovered that returning from authentication.BaseAuthentication's authenticate method is wrong. The best way is to raise an exception like this otherwise things get weird.

raise exceptions.AuthenticationFailed('Your message here')

answered Jul 15, 2019 at 9:20

Carl

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1 Comment

Calum Mackervoy Over a year ago

It would have been helpful to include from rest_framework.exceptions import AuthenticationFailed in your answer so it was clear this was what you were using. Otherwise thanks this solved my issue

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