Question

I’ve got a nested object (object with subobjects) that I’d like to retrieve from a repository associated with an active session from one database, evict it, and save it in another database (different session, different connection string, different repository). I have tried:

myISession.Evict(myObjectInstance);

My MappingConfiguration has

Conventions.Add(DefaultCascade.All())

for all types.

But I still get “NHibernate.HibernateException: Illegal attempt to associate a collection with two open sessions”. How can I remove the association with the original session?

Answer 1

OK, it turns out my object, in this case myObjectInstance was composed of objects from two different sessions, let’s call them A and B. myObjectInstance had properties myProp1 from session A, and myProp2 from session B. I was then to store the whole myObjectInstance in session B.

Unfortunately I was trying to evict myObjectInstance from session A, rather than just myProp1.

The solution was to:

NHibernateUtil.Initialize(myObjectInstance.myProp1); //eager load object being evicted.
_dataSession.Evict(myObjectInstance.myProp1);
MyObjectRepository.Save(myObjectInstance);