Hi,

I've got two classes like Car and Bike which both inherit from Vehicle and are stored using a single table strategy.

Now I would like to change the class of a persistent object without changing its id. Yes, I do have a need for that :-)

In plain database terms it would mean to modify the discriminator field's value for that row (and perhaps some fields representing the instance's properties).

But is there a way to do that in Hibernate?

I've tried to turn a bike into a car with some code like this:

//retrieve bike from database
...

id = bike.getId();
entityManager.clear();

car = new Car();
car.setId(id);
entityManager.merge(car);

But that just creates a new car without caring about the id I set.

Any ideas appreciated!

Norbert

I doubt you can do this, because Java doesn't allow it. You'll have to take care of it outside of a hibernate transaction.