Refactored get_query_set_class() to DatabaseOperations.query_set_class(). Also…

Refactored get_query_set_class() to DatabaseOperations.query_set_class(). Also added BaseDatabaseFeatures.uses_custom_queryset. Refs #5106

git-svn-id: http://code.djangoproject.com/svn/django/trunk@5976 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/backends/__init__.py

@@ -48,6 +48,7 @@ class BaseDatabaseFeatures(object):
     supports_constraints = True
     supports_tablespaces = False
     uses_case_insensitive_names = False
+    uses_custom_queryset = False
 
 class BaseDatabaseOperations(object):
     """
@@ -144,6 +145,15 @@ class BaseDatabaseOperations(object):
         """
         return 'DEFAULT'
 
+    def query_set_class(self, DefaultQuerySet):
+        """
+        Given the default QuerySet class, returns a custom QuerySet class
+        to use for this backend. Returns None if a custom QuerySet isn't used.
+        See also BaseDatabaseFeatures.uses_custom_queryset, which regulates
+        whether this method is called at all.
+        """
+        return None
+
     def quote_name(self, name):
         """
         Returns a quoted version of the given table, index or column name. Does

django/db/models/query.py

@@ -564,9 +564,9 @@ class _QuerySet(object):
 
         return select, " ".join(sql), params
 
-# Use the backend's QuerySet class if it defines one, otherwise use _QuerySet.
-if hasattr(backend, 'get_query_set_class'):
-    QuerySet = backend.get_query_set_class(_QuerySet)
+# Use the backend's QuerySet class if it defines one. Otherwise, use _QuerySet.
+if connection.features.uses_custom_queryset:
+    QuerySet = connection.ops.query_set_class(_QuerySet)
 else:
     QuerySet = _QuerySet