Remove ordering filter class handling

These filters are already applied by GenericAPIView.filter_queryset()

Author: ulgens

rest_framework/pagination.py

@@ -624,7 +624,7 @@ def paginate_queryset(self, queryset, request, view=None):
 
         # Cursor pagination always enforces an ordering.
         if not queryset.ordered:
-            self.ordering = self.get_ordering(request, queryset, view)
+            self.ordering = self.get_ordering()
 
             if reverse:
                 queryset = queryset.order_by(*_reverse_ordering(self.ordering))
@@ -803,47 +803,29 @@ def get_previous_link(self):
         cursor = Cursor(offset=offset, reverse=True, position=position)
         return self.encode_cursor(cursor)
 
-    def get_ordering(self, request, queryset, view):
+    def get_ordering(self):
         """
         Return a tuple of strings, that may be used in an `order_by` method.
         """
-        # The default case is to check for an `ordering` attribute
-        # on this pagination instance.
-        ordering = self.ordering
-
-        ordering_filters = [
-            filter_cls for filter_cls in getattr(view, 'filter_backends', [])
-            if hasattr(filter_cls, 'get_ordering')
-        ]
-
-        if ordering_filters:
-            # If a filter exists on the view that implements `get_ordering`
-            # then we defer to that filter to determine the ordering.
-            filter_cls = ordering_filters[0]
-            filter_instance = filter_cls()
-            ordering_from_filter = filter_instance.get_ordering(request, queryset, view)
-            if ordering_from_filter:
-                ordering = ordering_from_filter
-
-        assert ordering is not None, (
+        assert self.ordering is not None, (
             'Using cursor pagination, but no ordering attribute was declared '
             'on the pagination class.'
         )
-        assert '__' not in ordering, (
+        assert '__' not in self.ordering, (
             'Cursor pagination does not support double underscore lookups '
             'for orderings. Orderings should be an unchanging, unique or '
             'nearly-unique field on the model, such as "-created" or "pk".'
         )
 
-        assert isinstance(ordering, (str, list, tuple)), (
+        assert isinstance(self.ordering, (str, list, tuple)), (
             'Invalid ordering. Expected string or tuple, but got {type}'.format(
-                type=type(ordering).__name__
+                type=type(self.ordering).__name__
             )
         )
 
-        if isinstance(ordering, str):
-            return (ordering,)
-        return tuple(ordering)
+        if isinstance(self.ordering, str):
+            return (self.ordering,)
+        return tuple(self.ordering)
 
     def decode_cursor(self, request):
         """

tests/test_pagination.py

@@ -616,42 +616,6 @@ def test_invalid_cursor(self):
         with pytest.raises(exceptions.NotFound):
             self.pagination.paginate_queryset(self.queryset, request)
 
-    def test_use_with_ordering_filter(self):
-        class MockView:
-            filter_backends = (filters.OrderingFilter,)
-            ordering_fields = ['username', 'created']
-            ordering = 'created'
-
-        request = Request(factory.get('/', {'ordering': 'username'}))
-        ordering = self.pagination.get_ordering(request, [], MockView())
-        assert ordering == ('username',)
-
-        request = Request(factory.get('/', {'ordering': '-username'}))
-        ordering = self.pagination.get_ordering(request, [], MockView())
-        assert ordering == ('-username',)
-
-        request = Request(factory.get('/', {'ordering': 'invalid'}))
-        ordering = self.pagination.get_ordering(request, [], MockView())
-        assert ordering == ('created',)
-
-    def test_use_with_ordering_filter_without_ordering_default_value(self):
-        class MockView:
-            filter_backends = (filters.OrderingFilter,)
-            ordering_fields = ['username', 'created']
-
-        request = Request(factory.get('/'))
-        ordering = self.pagination.get_ordering(request, [], MockView())
-        # it gets the value of `ordering` provided by CursorPagination
-        assert ordering == ('created',)
-
-        request = Request(factory.get('/', {'ordering': 'username'}))
-        ordering = self.pagination.get_ordering(request, [], MockView())
-        assert ordering == ('username',)
-
-        request = Request(factory.get('/', {'ordering': 'invalid'}))
-        ordering = self.pagination.get_ordering(request, [], MockView())
-        assert ordering == ('created',)
-
     def test_cursor_pagination(self):
         (previous, current, next, previous_url, next_url) = self.get_pages('/')