Hi,

I am using Hibernate version: 3.13

I want to execute multiple operations in one session for my User object. Basically first I am creating a user object and then deleting that object in same session. But deletion of object fails with following exception:

org.hibernate.NonUniqueObjectException: a different object with the same identifier value was already associated with the session:

I have tried using merge() and evict() before deleting the object but it fails.

Here is my program:

DAO CLASS METHODS
=====================
public User create(User user) {
String id = (String)session.save(user);
User retUser = (User)user.clone();
retUser.setId(id);
return retUser;
}

public void delete(String id) {
User user = new User();
user.setId(id);
session.delete(user);
}

public startOperation() {
session = HibernateFactory.getSession();
tx = session.beginTransaction();
}

public void commit() {
tx.commit();
}

public void rollback() {
tx.rollback();
}

public void close() {
session.close();
}

TEST CLIENT
===================
try {
dao.startOperation();
// add an object
User user = new User();
User retUser = dao.create(user);
// delete object
dao.delete(retUser.getId());
dao.commit();
} catch (Exception ex) {
dao.rollback();
} finally {
dao.close();
}

Thanks.

Sanjeev

flush the session as indicated by the comment line in the code.

this topic (http://forum.hibernate.org/viewtopic.php?t=959555) already discussed and have some comments

This is the way Hibernate works.
You can:
- evict object from session after saving; (not avisable)
- or you can check for the object presence in the sesion in the delete method:
O o = session.get( User.class, id );
if( o != null ){
session.delete( o );
}else{
your current code in the delete method
}

Thanks.

I have tried to get the object from session and it works.

Does this mean if I do more operations in one session such as update or retreive then I should try to get the object first from session.

Is there will be any performance issue when I will first try to get the object from session (like any database call).


DAO CLASS METHODS
=====================
public void delete(String id) {
Object o = session.get( User.class, id );
if( o != null ){
session.delete( o );
}else{
User user = new User();
user.setId(id);
session.delete(user);
}

public User retrieve(String id) {
Object obj = session.get(User.class, id);
if (obj == null) {
session.load(User.class, id);
}
}


TEST CLIENT
===================
try {
startOperation();
// add an object
User retUser = dao.create(user);

// get object
User retuser2 = dao.retrieve(retUser.getId());

// delete object
dao.delete(retUser.getId());

dao.commit();
} catch (Exception ex) {
dao.rollback();
} finally {
dao.close();
}

Thanks.

Sanjeev

session.lock( userObj, LockMode.NONE );

will not require a SELECT.

No.
session.load( ) tries to loads object from DB, get() - does not

Hello,
you can do multiple actions on objects in the session without flushing. Flushing is needed in rare cases for objects in relation when you need to create a db generated primary key first.

Your problem is IMHO that you are cloning the user. You assign the primary key, save the user then clone it and start deleting the cloned one. Than Hibernate detects that there is allready a user with the same primary key in the session. Do not clone.

Best Regards
Sebastian