title: Django Rest Framework - "detail": "Not found."
body: <p>Hi when doing this request: groups/25010a31-fc5b-47c8-9c5c-d740e5743f52/members/4/ - I get "detail": "Not found"</p>
  
  <p>However, if you look in the queryset I have printed the Groupmember instance and this ends up printing out that particular instance so clearly it exists?</p>
  
  <p>View:</p>
  
  <pre><code>class MemberDetail(mixins.RetrieveModelMixin,
                     mixins.DestroyModelMixin,
                     mixins.UpdateModelMixin,
                     generics.GenericAPIView):
      serializer_class = GroupMembersSerializer
      lookup_field = "user_id"
      lookup_url_kwarg = "uuid"
  
      def get_queryset(self):
          group = self.kwargs["uuid"]
          user_id = self.kwargs["user_id"]
          print GroupMember.objects.get(group = group, user_id = user_id)
          return GroupMember.objects.get(group = group, user_id = user_id)
  
      def get(self, request, *args, **kwargs):
          return self.retrieve(self, request, *args, **kwargs)
  
      def put(self, request, *args, **kwargs):
          return self.update(self, request, *args, **kwargs)
  
      def delete(self, request, *args, **kwargs):
          return self.destroy(self, request, *args, **kwargs)
  </code></pre>
  
  <p>urls: </p>
  
  <pre><code> urlpatterns = [
  
      url(r'^$', views.GroupList.as_view()),
      url(r'^(?P&lt;uuid&gt;[^/]+)/$', views.GroupDetail.as_view()),
      url(r'^(?P&lt;uuid&gt;[^/]+)/members/$', views.MemberList.as_view()),
      url(r'^(?P&lt;uuid&gt;[^/]+)/members/(?P&lt;user_id&gt;[0-9]+)/$', views.MemberDetail.as_view()),
  
  ] 
  </code></pre>
  
  <p>Any help?</p>