* Use get_serializer_class in ordering filter* Test improper configuration of ordering* Raise ImproperlyConfigured when missing get_serializer_class

* Use get_serializer_class in ordering filter
* Test improper configuration of ordering
* Raise ImproperlyConfigured when missing get_serializer_class

Author: kmwenja

rest_framework/filters.py

@@ -227,11 +227,14 @@ def get_valid_fields(self, queryset, view):
 
         if valid_fields is None:
             # Default to allowing filtering on serializer fields
-            serializer_class = getattr(view, 'serializer_class')
-            if serializer_class is None:
+            try:
+                serializer_class = view.get_serializer_class()
+            except AssertionError:  # raised if no serializer_class was found
                 msg = ("Cannot use %s on a view which does not have either a "
-                       "'serializer_class' or 'ordering_fields' attribute.")
+                       "'serializer_class', an overriding 'get_serializer_class' "
+                       "or 'ordering_fields' attribute.")
                 raise ImproperlyConfigured(msg % self.__class__.__name__)
+
             valid_fields = [
                 (field.source or field_name, field.label)
                 for field_name, field in serializer_class().fields.items()

tests/test_filters.py

@@ -5,6 +5,7 @@
 from decimal import Decimal
 
 from django.conf.urls import url
+from django.core.exceptions import ImproperlyConfigured
 from django.core.urlresolvers import reverse
 from django.db import models
 from django.test import TestCase
@@ -754,6 +755,41 @@ class OrderingListView(generics.ListAPIView):
 
         self.assertContains(response, 'verbose title')
 
+    def test_ordering_with_overridden_get_serializer_class(self):
+        class OrderingListView(generics.ListAPIView):
+            queryset = OrderingFilterModel.objects.all()
+            filter_backends = (filters.OrderingFilter,)
+            ordering = ('title',)
+            # note: no ordering_fields and serializer_class speficied
+
+            def get_serializer_class(self):
+                return OrderingFilterSerializer
+
+        view = OrderingListView.as_view()
+        request = factory.get('/', {'ordering': 'text'})
+        response = view(request)
+        self.assertEqual(
+            response.data,
+            [
+                {'id': 1, 'title': 'zyx', 'text': 'abc'},
+                {'id': 2, 'title': 'yxw', 'text': 'bcd'},
+                {'id': 3, 'title': 'xwv', 'text': 'cde'},
+            ]
+        )
+
+    def test_ordering_with_improper_configuration(self):
+        class OrderingListView(generics.ListAPIView):
+            queryset = OrderingFilterModel.objects.all()
+            filter_backends = (filters.OrderingFilter,)
+            ordering = ('title',)
+            # note: no ordering_fields and serializer_class
+            # or get_serializer_class speficied
+
+        view = OrderingListView.as_view()
+        request = factory.get('/', {'ordering': 'text'})
+        with self.assertRaises(ImproperlyConfigured):
+            view(request)
+
 
 class SensitiveOrderingFilterModel(models.Model):
     username = models.CharField(max_length=20)