title: 'CityListViewSet' should either include a `serializer_class` attribute, or override the `get_serializer_class()` method
body: <p>I am assuming by the error in the title, once more here for clarity</p>
  
  <pre><code>'CityListViewSet' should either include a `serializer_class` attribute, 
  or override the `get_serializer_class()` method.
  </code></pre>
  
  <p>that my serializer isn't connected to my view, which in my code it should be. I'm not really sure where the bug is in this one. I wonder if any of you have seen something similar?</p>
  
  <p>Here is the code.</p>
  
  <p>Router: </p>
  
  <pre><code>router.register(r'city-list', CityListViewSet, base_name='city-list')
  </code></pre>
  
  <p>view: </p>
  
  <pre><code>class CityListViewSet(viewsets.ReadOnlyModelViewSet):                 
      queryset = Venue.objects.values('city').distinct()
      serializer = CitySerializer(queryset, many=True)
      ordering_fields = ('city',)
      ordering = ('city',)
  </code></pre>
  
  <p>serializer: </p>
  
  <pre><code>class CitySerializer(serializers.ModelSerializer):    
      class Meta:
          model = City
          fields =('city',)
  </code></pre>
  
  <p>what is it that would be causing such an assertion error with the code seemly wired up correctly?</p>