PersistentObjectException: detached entity passed to persist

[jeff mutonho]

I'm trying to do a simple persisting of an object into a MySQL database , with the following code:

public static void main(String[] args){
 EntityManager em=JPAUtility.getEntityManager();
 List existing = JPAUtility.getEntityManager().createQuery("select u  from UserBean u where u.userName='foo' and u.password='bar'").getResultList();
 if (existing.size() == 0) {
 System.out.println("User not in db...inserting");
 UserBean user = new UserBean();
 JPAUtility.beginTransaction();
 user.setId(1);
 user.setUserName("foo");
 user.setPassword("bar");
 em.persist(user);
 JPAUtility.commitTransaction();
 System.out.println("Persisted user "+user.getUserName());
} else {
System.out.println("Already in db...");
}
  }

When I run this I'm getting a org.hibernate.PersistentObjectException: detached entity passed to persist .The full stacktrace is as follows:

User not in db...inserting
Exception in thread "main" javax.persistence.PersistenceException: org.hibernate.PersistentObjectException: detached entity passed to persist: com.introspect.tutorial.UserBean
at org.hibernate.ejb.AbstractEntityManagerImpl.throwPersistenceException(AbstractEntityManagerImpl.java:629)
at org.hibernate.ejb.AbstractEntityManagerImpl.persist(AbstractEntityManagerImpl.java:218)
at com.introspect.tutorial.JPAUtility.main(JPAUtility.java:172)
Caused by: org.hibernate.PersistentObjectException: detached entity passed to persist: com.introspect.tutorial.UserBean
at org.hibernate.event.def.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:79)
at org.hibernate.event.def.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:38)
at org.hibernate.impl.SessionImpl.firePersist(SessionImpl.java:618)
at org.hibernate.impl.SessionImpl.persist(SessionImpl.java:592)
at org.hibernate.impl.SessionImpl.persist(SessionImpl.java:596)
at org.hibernate.ejb.AbstractEntityManagerImpl.persist(AbstractEntityManagerImpl.java:212)
... 1 more

[srinivas bodduluri]

The way you presented in the first code snippet for the lines

  UserBean user = new UserBean();   
 JPAUtility.beginTransaction();     

is wrong.

you need to create UserBean object after beginning the transaction.

or what you can do is

instead of em.parsist just use merge. since user object in the above code treat it as detached object. you will have to reattach by using merge but not with parsist.