Add conditionals specific to deferred for expire ro properties

Fixed bug where a :func:`.column_property` that is also marked as
"deferred" would be marked as "expired" during a flush, causing it
to be loaded along with the unexpiry of regular attributes even
though this attribute was never accessed.

Change-Id: Iaa9e17b66ece30a8e729e4af746b31ff99b1ec9a
Fixes: #3984

1 files changed, 10 insertions, 2 deletions

diff --git a/lib/sqlalchemy/orm/persistence.py b/lib/sqlalchemy/orm/persistence.py
index 5dc5a90b1..588a1d696 100644
--- a/lib/sqlalchemy/orm/persistence.py
+++ b/lib/sqlalchemy/orm/persistence.py
@@ -982,8 +982,16 @@ def _finalize_insert_update_commands(base_mapper, uowtransaction, states):
 
         if mapper._readonly_props:
             readonly = state.unmodified_intersection(
-                [p.key for p in mapper._readonly_props
-                    if p.expire_on_flush or p.key not in state.dict]
+                [
+                    p.key for p in mapper._readonly_props
+                    if (
+                        p.expire_on_flush and
+                        (not p.deferred or p.key in state.dict)
+                    ) or (
+                        not p.expire_on_flush and
+                        not p.deferred and p.key not in state.dict
+                    )
+                ]
             )
             if readonly:
                 state._expire_attributes(state.dict, readonly)