It seems you cannot clone objects with attributes using lazy loading in JPA

Question

I have an entity with an attribute using lazy loading:
@Entity
public class B {
@ManyToOne(fetch=FetchType.LAZY)
private A a;
@Entity
public class A {
Assume the following code:
A a1 = new A();
A a2 = new A();
B b1 = EntityManager.find(B.class, ...);
b1.setA(a1);
B b2 = b1.clone();
b2.setA(a2);
Now with lazy loading enabled I get b1.getA() == a2 instead of b1.getA() == a1. Moreover, the debugger displays the same value holder in b1 and b2 for the attribute a. It appears as if cloning does not make a (deep) copy of the value holder managing the attribute a.
How can I create a copy b2 of b1, such that the value holder managing a in b1 is a different object as the value holder managing a in b2?
Thanks, Thomas.

Answer 1

I have filed a bug to have this addressed in Oracle TopLink 11gR1. I would recommend you file a bug against TopLink Essentials in GlassFish or if you have a support contract report the issue to metalink to have the issue resolved.
If this is urgent I did try fixing the issue with a small helper method using some reflection. This method is simplified through its throwing of Exception. If you wish to use something like this I would recommend proper error handling.
     * Helper method for cloning an entity and fixing the woven value-holders to
     * complete a proper shallow cloning.
    public static Employee clone(Employee entity) throws Exception {
       Employee clone = entity.clone();
       // Now fix the cloned ValueHolder references
       Field[] fields = entity.getClass().getDeclaredFields();
       for (int index = 0; index < fields.length; index++) {
           Field field = fields[index];
           if (field.getName().startsWith("_toplink_")) {
               field.setAccessible(true);
               ValueHolderInterface vhi = (ValueHolderInterface)field.get(entity);
               Object value = vhi.isInstantiated() ? vhi.getValue() : null;
               field.set(clone, new ValueHolder(value));
       return clone;
    }Doug