JPA Container管理的事务-如何在同一事务中更新多个实体

Question

I'm still new to JPA and how the entity manager works. I have an application configured with container managed transactions, and I'm trying to figure out how to persist multiple objects in a single transaction. Here is what I tried first:

@Stateless
public class UserManager{
 @PersistenceContext(unitname="dataPortal")
 EntityManager em;

 public void insertUser(User user)
 {
  em.getTransaction().begin();
  ChangeEvent event = new ChangeEvent("user created");
  em.persist(u);
  em.persist(event);
  em.getTransaction().commit();
 }

}

This throws an illegal state exception when I try to get the transaction. I found out through reading that you aren't suppose to touch the transaction when it is container managed.

What I want to do is make sure that the User and ChangeEvent objects are persisted in the same transaction. How can I enforce that with container managed transactions?

Answer 1

Like you already said, the transactions are managed by the container.

If you want that both User and ChangeEvent are persisted in the same transaction just annotate your method the following way:

@TransactionAttribute(TransactionAttributeType.REQUIRES_NEW)
@TransactionManagement(TransactionManagementType.CONTAINER) 
public void insertUser(User user)
     {
      ChangeEvent event = new ChangeEvent("user created");
      em.persist(u);
      em.persist(event);
     }

This should do the trick. If you have further questions, feel free to ask.