JPA remove detached entity - jpa

Question

I've just begun working with JPA and hibernate, and I have been able to insert query and update on one table, but I cannot seem to delete an entity. Even after I attach the entity with the merge function, the program insists it is detached. Here is the relevant code:
public User getUserByEmail(String email) throws DAOException{
User user = null;
EntityManager em = null; //declare here for use in finally block
try{
//get em for use
EntityManagerFactory factory = JPAUtil.getEntityManagerFactory();
em = factory.createEntityManager();
//setup return type as user
CriteriaBuilder cb = em.getCriteriaBuilder();
CriteriaQuery<User> criteriaQuery = cb.createQuery(User.class);
Root<User> userRoot = criteriaQuery.from(User.class);
//populate the where clause
criteriaQuery.where(cb.equal(userRoot.get("email"), cb.parameter(String.class, "email")));
Query query = em.createQuery(criteriaQuery);
query.setParameter("email", email);
//actually run the query on db
user = (User) query.getSingleResult();
}catch(Exception ex){
DAOException dE = new DAOException(2, "getUserByEmail failed", ex);
//TODO log
throw dE;
}
//cleanup
finally{
if(em != null && em.isOpen()){
em.close();
}
}
return user; //if not found, will still be null
}
#Override
/*
* (non-Javadoc)
* #see dao.IUserDAO#deleteUser(java.lang.String)
*/
public void deleteUser(String email) throws DAOException {
EntityManagerFactory entityManagerFactory;
EntityManager em = null;
EntityTransaction trans = null;
try{
//search user on email
User user = getUserByEmail(email);
//check we found user with specified email
if(user != null){
//setup for interaction with database
entityManagerFactory = JPAUtil.getEntityManagerFactory();
em = entityManagerFactory.createEntityManager();
//alterations of db must occur in scope of transaction
trans = em.getTransaction();
trans.begin();
em.merge(user); //TODO update find to take transaction as parameter
em.remove(user);
trans.commit();
//explicitly flush here
em.flush();
}else{
//TODO we didn't find the user
}
}catch(Exception ex){
DAOException dE = new DAOException(6, "delete failed", ex);
//TODO log
trans.rollback();
throw dE;
}finally{
if(em != null && em.isOpen()){
em.close();
}
}
}
And here is the output from the eclipse console:
"Removing a deattached instance of User#1".
Could someone explain why this bean is still deattached after I explicitly called merge? Also, how would I fix this problem? Thanks.

Answer 1

The content of the specified detached entity object is copied into an
existing managed entity object with the same identity (i.e. same type
and primary key). If the EntityManager does not manage such an entity
object yet a new managed entity object is constructed. The detached
object itself, however, remains unchanged and detached.
Even after merge the detached object itself remains detached, merge will return the new created merged entity
user = em.merge(user); //TODO update find to take transaction as parameter
em.remove(user);