remove object from session in hibernate?

Question

Hi there,

my case is that, i've loaded an object X from DB using hibernateTemplate find by id, then i get some attributes from that object and added it to another object Y from the same type which was also loaded by the same X id, then i tried to saveOrUpdate object Y, hibernate thrown exception 'a different object with the same identifier value was already associated with the session' which means as i think that object X is associated with that attribute in the same session, so Y can't be saved or updated and affect also that attribute

so how can i remove object X from session so it's no more associated to that attribute

i tried to use merge instead of saveOrUpdate and it's working fine, but is it the same as saveOrUpdate, i mean can i depend on it to add new records or update them?

Answer 1

Perhaps you can try session.evict().

Answer 2

After a lot of tries, i found that using merge is the best approach to handle this effectively, and to take care of new instances to be saved i think best approach is to do this

        'if (X.getId() != null) {
            return hibernateTemplate.merge(X);
        } else {
            hibernateTemplate.saveOrUpdate(X);
        }'

so if it was a new instance to session it'll be done through saveOrUpdate, and if it's a duplicated instance for the same rows, it'll be handled using merge