Persisting an object in Hibernate while having a known primary key.

Question

My problem is with detached objects...

I am currently using Spring with Hibernate.

I have a mapped object that has a primary key as a String (I know it sucks... but refactoring the code would take months), and I wish to persist it. (I have simplified the object with just two attributes)

@Id
private String id;

private String pattern;

So for example I want to add something like:

["id":"myFirstPattern","pattern":".*"]

Notice that my primary key is already set. The problem with that is that whenever I try to persist, Hibernate will try to link this object with any object within the context (because of the primary key) and will fail to do so, since there are none. Throwing a detached object error.

I've done some research and came to the conclusion that merge() would suffice my needs, since it persists and updates even if the object is not available. However I found this a rather dirty workaround and wanted to check if there are any other solutions to this problem.

Take into account that we have a Helper layer, so Services layer will not work directly with the HibernateDao layer. So I can "mask" this by adding 'persist' and 'update' methods that will invoke the same merge DAO method.

Thanks, Flavio.

Answer 1

Have you tried saveOrUpdate?

Session sess = factory.openSession();
Transaction tx;
try {
    tx = sess.beginTransaction();
    session.saveOrUpdate( yourObjectHere );

    tx.commit();
}
catch (Exception e) {
    if (tx!=null) tx.rollback();
    throw e;
}
finally {
    sess.close();
}