Issues updating with Unit of Work

Question

Hello,
I think, I might be missing a point about toplink. I know that when I need to update an Object, i find the current object in cache(ReadObject) and then register that object to get a cloned object and do updates on the cloned object and then commit it.
Everything works fine in above scenario, IF AND ONLY IF, I set the attributes of the cloned object individually. But the update doesn't work if I set the cloned object to a totally different object (clonedObj = otherObj) Here otherObj has changed attributes which i want to be updated. Toplink somehow doesn't like it.
How do i do it?
Sample working code:
public void mergeData(Object obj, Class c){
try{
ReadObjectQuery query = ReadObjectQuery(obj);
// get the object with the primary key as the one passed in
Object persistableObject = session.executeQuery(query);
Object objectClone = tx.register(persistableObject);
//It is a User object
((User)objectClone).setName("New Neeraj");
tx.commit();
Sample NOT working code
public void mergeData(Object obj, Class c){
try{
ReadObjectQuery query = ReadObjectQuery(obj);
// get the object with the primary key as the one passed in
Object persistableObject = session.executeQuery(query);
Object objectClone = tx.register(persistableObject);
objectClone = obj //passed in object
tx.commit();
Is it becuase of the ReadObjectQuery using the same object as used to set up the cloned object?
Thanks in advance for the help.
Regards,
Neeraj

Answer 1

Don,
This is what the documentation says related to mergeClone:
"Merge the attributes of the clone into the unit of work copy. This can be used for objects that are returned from the client through RMI serialization (or another serialization mechanism), because the RMI object will be a clone this will merge its attributes correctly to preserve object identity within the unit of work and record its changes. The object and its private owned parts are merged."
What is the significance RMI and serialization in this.
I tries mergeClone locally (using the UOW) and it works fine, but just want to make sure that I understand what the documentation says.
Also, if you will be kind enough to explain the difference between mergeClone and mergeCloneWithReferences.
Thanks,
Neeraj