How can I make a copy of an existing data object, changing only the PK value?

For example,

Class A {
Long id; //is PK
String value;
......
}


This is essentially what I want, but it obviously doesn't work because of the way Hibernate's sessions work. Hibernate identifies the object as already existing in the session cache, and doesn't like changing the key.

aInstance = session.load(A.class,new Long(1));
aInstance.setID(new Long(2));
session.save(aInstance);


Any Ideas? How about if I do an evict(aInstance) right after I load it? Can I load an object without actually having Hibernate store it in the cache?

Hibernate does not allow changing the id of a persistent object for obvious reasons. You can copy a persistent object by creating a transient object (e.g. with new) and setting/copying its attributes, including the id.

mota

Well... just clone your object or define a copy-constructor. You can then safely change its id without disturbing Hibernate.

Thanks. I figured it would come down to doing it manually, I just wanted to ask to see if there was something out there already. The cloning becomes more complicated when there are associations mapped in the class as well, but nothing I can't handle!

Thanks again.