How to start a transaction in JPA using entityManager

Question

I have started working on an application which uses spring, hibernate, JPA, SOAP webservices. Now there is a requirement that certain queries have to be run in a transaction

Answer 1

The EntityManager instance returned by @PersistenceContext is always a container managed EntityManager. And container managed EntityManager are always JTA EntityManagers and hence their lifecycle is managed by the container. I guess now it makes sense as to why it is illegal to call getTransaction() on them.This might help

Answer 2

@Transactional annotation will do exactly what you need.

http://docs.spring.io/spring/docs/current/spring-framework-reference/html/transaction.html#transaction-declarative-annotations

Answer 3

The add a hibernate.jta.allowTransactionAccess property with the value true and you should be allowed to use it manually. Though it's not a good practice to mix your strategies, having some code managed by JTA, some manually.

Answer 4

Try injecting EntityManagerFactory and then creating the EntityManager manually:

@PersistenceUnit
private EntityManagerFactory entityManagerFactory;

public boolean processBills() throws Exception{

   EntityManager em = entityManagerFactory.createEntityManager();

   EntityTransaction tx = null;

   Session session = null;

   try{

       session = em.unwrap(Session.class);
       tx = em.getTransaction();