Hibernate Error: org.hibernate.NonUniqueObjectException: a different object with the same identifier value was already associated with the session

Question

Hi folks,

I have got almost the same problem like that user.

In my situation I load one entity from db, I convert this entity into a DataTransferObject, then I want to edit one attribute, after that I convert it back into an entityObject, then I update that entity and hibernate throws following error:

Hibernate Error: org.hibernate.NonUniqueObjectException: a different object with the same identifier value was already associated with the session

Apparently, the problem is that the object I retrieve from db has the same id as the one I want to update (like it should be) BUT those are not the same objects!

How to manage that? Thank you for help...

Answer 1

choose either one:

1 - you can close the session after loading the entity and open new session for update

2 - instead of creating new Entity for update, use the old one and edit it.

3 - detach your first entity from session - session.evict(myEntity)

Answer 2

Your problem is that the object you previously loaded still exists in you hibernate session. I see two ways to cope with that.

1.) tell the hibernate session to merge your modified object with the one in the session

session.merge(object)

2.) kick the old object out of the session before writing the updated object to the session. session.clear() might work.

Answer 3

Beyond just calling clear() on the session, it sounds like you might have a problem with the way you are using Hibernate:

Apparently, the problem is that the object I retrieve from db has the same id as the one I want to update (like it should be) BUT those are not the same objects!

Do you mean to say that you have two distinct entities which have the same ID? If so, then you should find a different field that uniquely identifies different entities.