Roll back transaction after exception in JPA + Spring

Question

I'm using Spring and JPA with HIbernate underneath. When a PersistenceException is thrown, I want to catch it and return the error message so that it is not propagated up to the caller.

@Transactional
public String save(Object bean) {
    String error = null;

    try {
        EntityManager entityManager = getEntityManager();

        for (int i = 0, n = entities.size(); i < n; i ++) {
            entityManager.merge(entities.get(i));
        }
    }
    catch (PersistenceException e) {
        error = e.getMessage();
    }

    return error;
}

But I get an exception saying that javax.persistence.RollbackException: Transaction marked as rollbackOnly. I get that the transaction needs to be rolled back after an exception but how do I roll it back when I've catched the exception and do not want to re-throw it?

Answer 1

By using @Transactional if there are any RuntimeExceptions thrown in the method, it will automatically perform the rollback. You don't need to manually do it. You probably shouldn't be catching that exception at all and instead let it pass to a higher level ExceptionHandler that shows some standard error page to the user (not the stack trace). Also your method is marked void but you are returning a String.

Answer 2

You can use Spring's Exception Translation with a custom PersistenceExceptionTranslator to translate PersistenceException into something useful.

Oh, btw, you shouldn't use @Transactional at the DAO level. Transactions should be started at the service level.

Answer 3

It appears that there is no way to roll back a failed transaction managed by Spring ORM. The code shown in the question is a service class. Extracting its persistence routine to a separate DAO class and having the service class handle PersistenceExceptions did the trick.