Question

Why do I need to use a transaction to persist an Entity? Is there something I can add to my persistence.xml to auto-commit?

This doesn’t insert:

em.persist(this);

But this does:

em.getTransaction().begin();
em.persist(this);
em.getTransaction().commit();

I guess my initial reference point was this GWT doco

public void persist() 
{
   EntityManager em = entityManager();
   try 
   {
     em.persist(this);
   } 
   finally 
   {
     em.close();    
   }  
}

Answer 1

JPA does not define such behaviour; any “persist()” is defined to wait til the next transaction according to the spec. Obviously some implementations of JPA (such as DataNucleus JPA) do provide that (auto-commit) facility, but it’s beyond (not part of) the JPA spec