Refs #27149 -- Moved subquery expression resolving to Query.

This makes Subquery a thin wrapper over Query and makes sure it respects
the Expression source expression API by accepting the same number of
expressions as it returns. Refs #30188.

It also makes OuterRef usable in Query without Subquery wrapping. This
should allow Query's internals to more easily perform subquery push downs
during split_exclude(). Refs #21703.

1 files changed, 15 insertions, 0 deletions

diff --git a/django/db/models/sql/where.py b/django/db/models/sql/where.py
index 9d3d6a9366..496822c58b 100644
--- a/django/db/models/sql/where.py
+++ b/django/db/models/sql/where.py
@@ -183,8 +183,23 @@ class WhereNode(tree.Node):
     def is_summary(self):
         return any(child.is_summary for child in self.children)
 
+    @staticmethod
+    def _resolve_rhs(rhs, query, *args, **kwargs):
+        if hasattr(rhs, 'resolve_expression'):
+            rhs = rhs.resolve_expression(query, *args, **kwargs)
+        return rhs
+
+    @classmethod
+    def _resolve_node(cls, node, query, *args, **kwargs):
+        if hasattr(node, 'children'):
+            for child in node.children:
+                cls._resolve_node(child, query, *args, **kwargs)
+        if hasattr(node, 'rhs'):
+            node.rhs = cls._resolve_rhs(node.rhs, query, *args, **kwargs)
+
     def resolve_expression(self, *args, **kwargs):
         clone = self.clone()
+        clone._resolve_node(clone, *args, **kwargs)
         clone.resolved = True
         return clone