Merge pull request #5348 from fbidu/4585

Adding a more explicit error message when a view does have a get_queryset method but it returned nothing

rest_framework/permissions.py

@@ -122,6 +122,9 @@ class DjangoModelPermissions(BasePermission):
 
         if hasattr(view, 'get_queryset'):
             queryset = view.get_queryset()
+            assert queryset is not None, (
+                '{}.get_queryset() returned None'.format(view.__class__.__name__)
+            )
         else:
             queryset = getattr(view, 'queryset', None)