title: Custom lookup_field with django rest framework, Cannot resolve detail
body: <p>The error I am getting is</p>
  
  <pre><code>ImproperlyConfigured at /usercombo/
  Could not resolve URL for hyperlinked relationship using view name "usercombo-detail". You may have failed to include the related model in your API, or incorrectly configured the `lookup_field` attribute on this field.
  </code></pre>
  
  <p>In my view.py</p>
  
  <pre><code>class UserComboViewSet(viewsets.ModelViewSet):
      """
      API endpoint that allows UserCombo to be viewed or edited.
      """
      queryset = UserCombo.objects.all()
      serializer_class = UserComboSerializer
      permission_classes = (IsAuthenticated,EmailConfirmationPermission) 
      lookup_field='customURL'
  
      def get_queryset(self):
          return  UserCombo.objects.filter(user=self.request.user)
  </code></pre>
  
  <p>In my serializer.py:</p>
  
  <pre><code>class UserCombo(serializers.HyperlinkedModelSerializer):
      customURL = serializers.CharField(
         required=False,)
  
      data = JSONSerializerField()
  
      class Meta:
          model = UserCombo
          unique_together = (("product", "user"),)
          fields = ('url', 'user', 'product', 'data', 'customURL', 'is_active')
          lookup_field ='customURL'
  </code></pre>
  
  <p>If I remove the two lookup_field lines everything works fine, but the lookup_field for the usercombo object is the pk.</p>