Is there an alternative to ISession.Merge() that doesn't throw when using optimistic locking?

Question

I've been trying to use ISession.Merge() to keep coherence between two sessions, but it fails when the merged instance has a higher Version property than the one loaded in the session (with a StaleObjectStateException).

Is there an alternative method that would work when the Version fields do not match ?

score 0 · Answer 1 · answered Jul 27 '11 at 20:22

0

Try calling:

Session.Lock(string entityName, object obj, LockMode lockMode);

with LockMode.Force. The remarks for that method state:

This may be used to perform a version check (NHibernate.LockMode.Read), to upgrade to a pessimistic lock (NHibernate.LockMode.Upgrade), or to simply reassociate a transient instance with a session (NHibernate.LockMode.None). This operation cascades to associated instances if the association is mapped with cascade="lock".

And for LockMode.Force:

Similar to NHibernate.LockMode.Upgrade except that, for versioned entities, it results in a forced version increment.

answered Jul 27 '11 at 20:22

eulerfx

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The documentation and litterature elsewere make me think that LockMode.Force will rather force a write of a new Version to the DB, rather than get the latest state...I'll see what I can do with it though. – Mathieu Garstecki Jul 29 '11 at 14:27
1

Confirmed, LockMode.Force forces NHibernate to send a SQL update, which is the opposite of what I want here. – Mathieu Garstecki Aug 02 '11 at 12:57

score 0 · Accepted Answer · answered Aug 08 '11 at 13:30

There doesn't seem to be any way to safely merge entities between sessions, at least with optimistic-locking.

I'm going with another pattern: each session has its own copies of each entity, and I refresh() the instances on each session as needed. This has added overhead in memory usage and round-trips to the DB, but it seems to work.

Is there an alternative to ISession.Merge() that doesn't throw when using optimistic locking?

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