Improve RelatedFilter queryset error message (#170)

Author: Ryan P Kilby

rest_framework_filters/filters.py

@@ -39,7 +39,8 @@ def fset(self, value):
     def get_queryset(self, request):
         queryset = super(RelatedFilter, self).get_queryset(request)
         assert queryset is not None, \
-            "Expected `.get_queryset()` to return a `QuerySet`, but got `None`."
+            "Expected `.get_queryset()` for related filter '%s.%s' to return a `QuerySet`, but got `None`." \
+            % (self.parent.__class__.__name__, self.name)
         return queryset
 
 

tests/test_filtering.py

@@ -347,7 +347,7 @@ class Meta:
             f.qs
 
         msg = str(excinfo.exception)
-        self.assertEqual("Expected `.get_queryset()` to return a `QuerySet`, but got `None`.", msg)
+        self.assertEqual("Expected `.get_queryset()` for related filter 'NoteFilter.author' to return a `QuerySet`, but got `None`.", msg)
 
     def test_relatedfilter_request_is_passed(self):
         class RequestCheck(FilterSet):