Hi all,
This is a slightly complicated problem, which I'm not sure how to tackle.
I get a
"""
StaleDataError: UPDATE statement on table 'D' expected to update 1 row(s); 0
were matched.
"""
in the following setup and action sequence:
Setup:
I have defined an association_proxy - named 'tasks' - from class A to class
C, via class B, like this
A -> B -> C
|
-->D
There is also a class D that has a 1-1 rel with class B. I have defined a
before_delete MapperExtension, as I want to delete D objects only under
certain conditions.
Now, assuming objects a,b,c,d, when I execute a.tasks = [], the association
proxy code nulls B's foreign key that references A, and my "all,
delete-orphan" cascade rule is then
responsible for actually deleting B objects. Subsequently, the before_delete
extension will delete D objects using a
connection.execute(Dtable.delete().where(..)) approach.
Anyway, at some point I get the StaleDataError and the cause of the
problems seems to be an UPDATE that is executed after a DELETE.
The last few lines are telling:
--
sqlalchemy.engine.base.Engine.0x...8e8c: INFO: DELETE FROM Dtable WHERE
Dtable.id = %s
sqlalchemy.engine.base.Engine.0x...8e8c: INFO: (4L,)
sqlalchemy.engine.base.Engine.0x...8e8c: INFO: DELETE FROM Btable WHERE
Btable.uuid = %s
sqlalchemy.engine.base.Engine.0x...8e8c: INFO:
('fe23694052ae469cbff12fa3b557118b',)
sqlalchemy.engine.base.Engine.0x...8e8c: INFO: DELETE FROM syncobjects WHERE
syncobjects.uuid = %s
sqlalchemy.engine.base.Engine.0x...8e8c: INFO:
('fe23694052ae469cbff12fa3b557118b',)
sqlalchemy.engine.base.Engine.0x...8e8c: INFO: UPDATE Dtable SET data_id=%s
WHERE Dtable.id = %s
sqlalchemy.engine.base.Engine.0x...8e8c: INFO: (None, 4L)
sqlalchemy.engine.base.Engine.0x...8e8c: INFO: ROLLBACK
--
A,B,C all inherit from a SyncObject class.
The problem appears _most_ of the time, but not _all_ of the time. Statement
ordering issue maybe ?
I'm using SA 0.6.6 with MySQL 5.1.49, though the same problem appears with
SQLite.
Many thanks,
A.
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