How do I implement Unit Of Work in Spring & JPA/Hibernate?

Question

I am trying to get my head around the concept of UOW and how I can implement it in my spring/jpa/hibernate app with DDD. I make my methods transactional, but how do I make sure that all the entities that have been changed in the transaction get persisted? Is it by using cascading collections or is there another way?

Answer 1

Hibernate implements Unit of Work internally. That is, all changes made to persistent entities inside a transaction are persisted automatically (unless you have a transaction with readOnly = true).

Cascading options are needed to configure transition of graphs of transient or detached entities to persistent state.

See also:

• 11.1. Hibernate object states

Answer 2

how do I make sure that all the entities that have been changed in the transaction get persisted?

That's default behaviour for the JPA EntityManager.

Read this section of the Java EE 5 tutorial (all the way down to Synchronizing Entity Data to the Database)