Question

I have the code below which will query an entity and set a random number:

    EntityManager em = EMF.get().createEntityManager();
    Profile user = null;
    Query q = null;
    try{
        q = em.createNamedQuery("Profile.getRandomProfile");
        q.setParameter("random", Math.random());
        q.setMaxResults(1);
        user = (Profile) q.getSingleResult();

        user.setRandom( Math.random() );

    } catch(NoResultException ex){
            ex.printStackTrace();
    }

I thought doing so will update random property of profile. Why isn’t it updated? How to update the random property?

Answer 1

You need to begin and commit a transaction around your changes.

See,

http://en.wikibooks.org/wiki/Java_Persistence/Transactions