Detaching objects

kash_meu · **Posted:** Thu May 08, 2008 4:10 pm

This is the body of the update function in the DAO class

org.hibernate.Transaction tx=getSession().beginTransaction();
getSession().update(instance);
tx.commit();

What does it mean by detaching objects and attaching objects?

naesc · **Joined:** Mon Apr 14, 2008 1:13 pm **Posts:** 11

A detached object is one that has been persistent, but its Session has been closed.

For example:

Code:

    Session session = factory.openSession();
    MyEntity myEntity = null;
    Transaction tx;
    try {
        tx = session.beginTransaction();
        //do some work
        entity = session.get(MyEntity.class, new Long(12345));
        ...
        tx.commit();
    } catch (Exception e) {
        if (tx!=null) tx.rollback();
        throw e;
    } finally {
        session.close();
    }
    // myEntity is now a detached instance
    System.out.println(myEntity.getFoo());

For more info on different stats of persistent objects, see this page: http://www.hibernate.org/hib_docs/reference/en/html/objectstate.html