Fix #58, filtering on nonexistent related field

Author: Ryan P Kilby

rest_framework_filters/filterset.py

@@ -122,6 +122,9 @@ def get_filters(self):
             filterset_class = related_filter.filterset
             filter_names = [filterset_class.get_filter_name(param) for param in rel_data.keys()]
 
+            # filter out empty values - indicates an unknown field (author__foobar__isnull)
+            filter_names = [f for f in filter_names if f is not None]
+
             # attempt to retrieve related filterset subset from the cache
             key = self.cache_key(filterset_class, filter_names)
             subset_class = self.cache_get(key)

tests/test_filterset.py

@@ -315,6 +315,25 @@ def test_get_filterset_subset(self):
         self.assertIn('email', filterset_class.base_filters)
         self.assertEqual(len(filterset_class.base_filters), 1)
 
+    def test_nonexistent_related_field(self):
+        """
+        Invalid filter keys (including those on related filters) are invalid
+        and should be ignored.
+
+        Related: https://github.com/philipn/django-rest-framework-filters/issues/58
+        """
+        GET = {
+            'author__nonexistent': 'foobar',
+        }
+        f = NoteFilterWithRelated(GET, queryset=Note.objects.all())
+        self.assertEqual(len(list(f)), 4)
+
+        GET = {
+            'author__nonexistent__isnull': 'foobar',
+        }
+        f = NoteFilterWithRelated(GET, queryset=Note.objects.all())
+        self.assertEqual(len(list(f)), 4)
+
 
 class MethodFilterTests(TestCase):