EntityManager throws TransactionRequiredException on merge() in JBoss JSF bean

Question

I've set up a JSF application on JBoss 5.0.1GA to present a list of Users in a table and allow deleting of individual users via a button next to each user.

When deleteUser is called, the call is passed to a UserDAOBean which gets an EntityManager injected from JBoss.

I'm using the code

public void delete(E entity)
{
    em.remove(em.merge(entity));
}

to delete the user (code was c&p from a JPA tutorial). Just calling em.remove(entity) has no effect and still causes the same exception.

When this line is reached, I'm getting a TransactionRequiredException:

(skipping apparently irrelevant stacktrace-stuff)

...

20:38:06,406 ERROR [[Faces Servlet]] Servlet.service() for servlet Faces Servlet threw exception javax.persistence.TransactionRequiredException: EntityManager must be access within a transaction at org.jboss.jpa.deployment.ManagedEntityManagerFactory.verifyInTx(ManagedEntityManagerFactory.java:155) at org.jboss.jpa.tx.TransactionScopedEntityManager.merge(TransactionScopedEntityManager.java:192) at at.fhj.itm.utils.DAOImplTemplate.delete(DAOImplTemplate.java:54) at at.fhj.itm.UserBean.delete(UserBean.java:53) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

...

I already tried to wrap a manually managed transaction (em.getTransaction().begin() + .commit() ) around it, but this failed because it is not allowed within JBoss container. I had no success with UserTransaction either. Searches on the web for this issue also turned up no similar case and solution.

Has anyone experienced something similar before and found a solution to this?

Answer 1

Found the missing link.

It was indeed a missing transaction but the solution was not to use the EntityManager to handle it but to add an injected UserTransaction.

@Resource
UserTransaction ut;
...
public void delete(E entity)
{
        ut.begin();
        em.remove(em.merge(entity));
        ut.commit();
}

Thanks to all suggestions which somehow over 100 corners lead to this solution.

Answer 2

Know this is an old question, but just in case somebody stumbles on this like me.

Try

em.joinTransaction();
em.remove(bean);
em.flush();

That's what we use in all our @Stateful beans.

If you are using Seam, you can also use @Transactional(TransactionPropagationType.REQUIRED) annotation.

Answer 3

Are you sure that you annotated you bean with @Stateless or register it with xml?

Try add transaction's annotation to you code, this can help you:

@TransactionAttribute(REQUIRED)
public void delete(E entity)
{
        em.remove(em.merge(entity));
}

But it seems strange, because this is default value if you don't set it explicitly.

Answer 4

只是注意：我们今天遇到了同样的问题，结果有人将EJB标记为TransactionAttributeType.NOT_SUPPORTED并将方法标记为TransactionAttributeType.REQUIRED，导致em.merge因缺少事务而失败。