Base automatic filterset model on the queryset model. Fixes #834.

rest_framework/filters.py

@@ -32,40 +32,33 @@ class DjangoFilterBackend(BaseFilterBackend):
     def __init__(self):
         assert django_filters, 'Using DjangoFilterBackend, but django-filter is not installed'
 
-    def get_filter_class(self, view):
+    def get_filter_class(self, view, queryset=None):
         """
         Return the django-filters `FilterSet` used to filter the queryset.
         """
         filter_class = getattr(view, 'filter_class', None)
         filter_fields = getattr(view, 'filter_fields', None)
-        model_cls = getattr(view, 'model', None)
-        queryset = getattr(view, 'queryset', None)
-        if model_cls is None and queryset is not None:
-            model_cls = queryset.model
 
         if filter_class:
             filter_model = filter_class.Meta.model
 
-            assert issubclass(filter_model, model_cls), \
-                'FilterSet model %s does not match view model %s' % \
-                (filter_model, model_cls)
+            assert issubclass(filter_model, queryset.model), \
+                'FilterSet model %s does not match queryset model %s' % \
+                (filter_model, queryset.model)
 
             return filter_class
 
         if filter_fields:
-            assert model_cls is not None, 'Cannot use DjangoFilterBackend ' \
-                'on a view which does not have a .model or .queryset attribute.'
-
             class AutoFilterSet(self.default_filter_set):
                 class Meta:
-                    model = model_cls
+                    model = queryset.model
                     fields = filter_fields
             return AutoFilterSet
 
         return None
 
     def filter_queryset(self, request, queryset, view):
-        filter_class = self.get_filter_class(view)
+        filter_class = self.get_filter_class(view, queryset)
 
         if filter_class:
             return filter_class(request.QUERY_PARAMS, queryset=queryset).qs

rest_framework/tests/filters.py

@@ -70,9 +70,19 @@ if django_filters:
         filter_fields = ['decimal', 'date']
         filter_backend = filters.DjangoFilterBackend
 
+    class GetQuerysetView(generics.ListCreateAPIView):
+        serializer_class = FilterableItemSerializer
+        filter_class = SeveralFieldsFilter
+        filter_backend = filters.DjangoFilterBackend
+
+        def get_queryset(self):
+            return FilterableItem.objects.all()
+
     urlpatterns = patterns('',
         url(r'^(?P<pk>\d+)/$', FilterClassDetailView.as_view(), name='detail-view'),
         url(r'^$', FilterClassRootView.as_view(), name='root-view'),
+        url(r'^get-queryset/$', GetQuerysetView.as_view(),
+            name='get-queryset-view'),
     )
 
 
@@ -148,6 +158,17 @@ class IntegrationTestFiltering(CommonFilteringTestCase):
         self.assertEqual(response.data, expected_data)
 
     @unittest.skipUnless(django_filters, 'django-filters not installed')
+    def test_filter_with_get_queryset_only(self):
+        """
+        Regression test for #834.
+        """
+        view = GetQuerysetView.as_view()
+        request = factory.get('/get-queryset/')
+        view(request).render()
+        # Used to raise "issubclass() arg 2 must be a class or tuple of classes"
+        # here when neither `model' nor `queryset' was specified.
+
+    @unittest.skipUnless(django_filters, 'django-filters not installed')
     def test_get_filtered_class_root_view(self):
         """
         GET requests to filtered ListCreateAPIView that have a filter_class set