Are they same? save=persist, update=merge, delete=remove

jbchurn · **Posted:** Mon May 05, 2008 12:08 am

Hi,

I'm just switching from Hibernate Core to JPA but still a bit uncertain with persist() & merge(). For remove(), I'm quite sure it's equivalent.

Are the following understanding correct?

Hibernate's Session.save() is same as JPA'S EntityManager.persist()
Hibernate's Session.update() is same as JPA'S EntityManager.merge()
Hibernate's Session.delete() is same as JPA'S EntityManager.remove()

Please advise.

hardy.ferentschik · **Posted:** Mon May 05, 2008 6:04 am

Hi,

I guess that's a good working assumption. However, there are differences for example in the return types of these methods.

The hibernate entity manager documentation says:

Quote:

Merging in EJB3 is similar to the saveOrUpdateCopy() method in native Hibernate. However, it is not the same as the saveOrUpdate() method, the given instance is not reattached with the persistence context, but a managed instance is returned by the merge() method.

I recommend reading through the entity manager documentation and looking at the examples there.

--Hardy

cbredesen · **Posted:** Thu May 08, 2008 5:59 pm

Also note that although these methods have similar behavior, they cascade separately. So if you have cascade="save", and you persist() something, that action will not be cascaded. Definitely check out the EM reference, as Hardy suggested. Pay particular attention to merge().