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82

answers:

1
Q: 

NHibernate: StaleStateException with delete triggers.

I have an NHibernate entity which contains a many-to-many list of related items. When a certain property of the entity changes, a database trigger is called that removes all associations between the entity and any entities that it is joined to. However, NHibernate throws a StaleStateException with a message along the lines of:

Batch update returned unexpected row count from update; actual row count: 0; expected: N

This presents a problem because it causes a rollback of the transaction and the entity is not saved. This arises because when the entity is updated, all of the entities in the many-to-many collection are also updated by NHibernate, but they no longer exist because of the trigger, which then causes the updates to fail giving back a row count of 0.

I unfortunately cannot change this database behavior and implement this entirely in NHibernate.

Is there anyway to prevent this behavior or update the entity without updating the entities in the many-to-many association?

A: 

Use set nocount on in the trigger

Diego Mijelshon  2010-09-03 21:11:12
This is not the problem. This occurs after the trigger executed and NHibernate is attempting to update the deleted entries. The deleted entries no longer exist, so 0 rows are affected which causes NHibernate to throw an exception because it expected N rows (the rows deleted by the trigger when the parent entity was updated) and not 0 rows.
Joshua Rodgers  2010-09-07 14:38:26
Have you actually tried what I said before downvoting? Also, if you have DB cascades (even if implemented by a trigger), you should tell NH by means of the on-delete attribute.
Diego Mijelshon  2010-09-07 16:13:48
I have tried what you said. In fact the trigger had "SET NOCOUNT ON" from the start. Please do not assume I don't know what I'm doing. You obviously did not thoroughly read my question before giving an answer that doesn't work.
Joshua Rodgers  2010-09-07 16:33:31
Actually, if you use triggers instead of ON DELETE CASCADE, I *do* assume you don't know what you're doing. More so if you don't post the code of the triggers, nor the classes, nor the mappings, expecting a magical answer to a poorly-defined problem.
Diego Mijelshon  2010-09-07 17:00:27

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