1 files changed, 11 insertions, 0 deletions
diff --git a/django/db/models/sql/where.py b/django/db/models/sql/where.py
index df44803b8a..bb4e9252b4 100644
--- a/django/db/models/sql/where.py
+++ b/django/db/models/sql/where.py
@@ -118,6 +118,13 @@ class WhereNode(tree.Node):
             cols.extend(child.get_group_by_cols())
         return cols
 
+    def get_source_expressions(self):
+        return self.children[:]
+
+    def set_source_expressions(self, children):
+        assert len(children) == len(self.children)
+        self.children = children
+
     def relabel_aliases(self, change_map):
         """
         Relabels the alias values of any children. 'change_map' is a dictionary
@@ -160,6 +167,10 @@ class WhereNode(tree.Node):
     def contains_aggregate(self):
         return self._contains_aggregate(self)
 
+    @property
+    def is_summary(self):
+        return any(child.is_summary for child in self.children)
+
 
 class NothingNode(object):
     """