Issue updating aggregate when setting foreign key to Null

[RaHus]

I have 2 tables defined as such

class BaseUserList(Base):
    id = Column(Integer, primary_key=True)
    ...
    event = relationship("Event", back_populates="base_user_list")

    @aggregated(
        "event", Column(Boolean, server_default=text("false"), nullable=False)
    )
    def _has_event(self):
        return func.count(Event.id) > 0

class Event(Base):
    id = Column(Integer, primary_key=True)
    ...
    base_user_list_id = Column(
        Integer, ForeignKey("user_list.id", ondelete="SET NULL"), index=True
    )
    base_user_list = relationship("BaseUserList", back_populates="event")

When i attach a list to the event the aggregate updates correctly

 ev=Event.q.get(83) # q is DBSession.query(Event)
 ev.base_user_list_id=2
 ev.flush()
 
 INFO  [sqlalchemy.engine.Engine][MainThread] UPDATE event SET updated_at=%(updated_at)s, base_user_list_id=%(base_user_list_id)s WHERE event.id = %(event_id)s
 INFO  [sqlalchemy.engine.Engine][MainThread] [cached since 2127s ago] {'updated_at': datetime.datetime(2024, 4, 1, 9, 20, 50, 634580), 'base_user_list_id': 2, 'event_id': 83}
 INFO  [sqlalchemy.engine.Engine][MainThread]  UPDATE user_list SET updated_at=%(updated_at)s, _has_event=(SELECT count(event.id) > %(count_1)s AS anon_1 
FROM event 
WHERE user_list.id = event.base_user_list_id) WHERE user_list.id IN (%(id_1_1)s)
 INFO  [sqlalchemy.engine.Engine][MainThread] [generated in 0.00018s] {'updated_at': datetime.datetime(2024, 4, 1, 9, 20, 50, 636710), 'id_1_1': 2}

But when i clear the foreign key in the Event class, the update query is wrong

ev.base_user_list_id=None

ev.flush()

UPDATE event SET updated_at=%(updated_at)s, base_user_list_id=%(base_user_list_id)s WHERE event.id = %(event_id)s
INFO  [sqlalchemy.engine.Engine][MainThread] [cached since 233.5s ago] {'updated_at': datetime.datetime(2024, 4, 1, 9, 26, 43, 931450), 'base_user_list_id': None, 'event_id': 83}
 INFO  [sqlalchemy.engine.Engine][MainThread] UPDATE user_list SET updated_at=%(updated_at)s, _has_event=(SELECT count(event.id) > %(count_1)s AS anon_1 
FROM event 
WHERE user_list.id = event.base_user_list_id) WHERE user_list.id IN (NULL)
INFO  [sqlalchemy.engine.Engine][MainThread] [generated in 0.00067s] {'updated_at': datetime.datetime(2024, 4, 1, 9, 26, 43, 938208), 'count_1': 0}

As you can see in the update query issued by sqlalchey_utils:

UPDATE user_list SET updated_at=..., _has_event=(SELECT count(event.id) > 0 AS anon_1 
FROM event 
WHERE user_list.id = event.base_user_list_id) WHERE user_list.id IN (NULL)

The update condition is WHERE user_list.id IN (NULL) which is something that never makes sense

Here the query generated should have used the value for base_user_list_id before the update

Also tried adding
base_user_list = relationship("BaseUserList", back_populates="event", uselist=False)
but it still results in the exact same query

[RaHus]

@kvesteri Any feedback for this one?