From: Mike Bayer <mike_mp@zzzcomputing.com>
Date: Tue, 22 Sep 2020 13:00:44 +0000 (-0400)
Subject: Expect collected weak reference in ORM listener
X-Git-Tag: rel_1_4_0b1~83
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=468766d6bac1e54a59c5f7d7167467dbc7d29a82;p=thirdparty%2Fsqlalchemy%2Fsqlalchemy.git

Expect collected weak reference in ORM listener

CI is showing that this listener may be triggered
when the target, a mapped class, has been garbage collected.

I'm not able to reproduce this locally.

Change-Id: Iad96c088a9a3dc28c4bcd716e293c03d3b312efd
---

diff --git a/lib/sqlalchemy/orm/events.py b/lib/sqlalchemy/orm/events.py
index ec907c63e7..0349c445ce 100644
--- a/lib/sqlalchemy/orm/events.py
+++ b/lib/sqlalchemy/orm/events.py
@@ -67,6 +67,9 @@ class InstrumentationEvents(event.Events):
 
         def listen(target_cls, *arg):
             listen_cls = target()
+            if listen_cls is None:
+                return None
+
             if propagate and issubclass(target_cls, listen_cls):
                 return fn(target_cls, *arg)
             elif not propagate and target_cls is listen_cls: