Question

I have the following 3 entities:

• entity class A implements interface X
• entity class B implements interface X
• entity class C

Where I could like entity class C to be able to hold a reference to an entity of type X, that is: either A or B.

Is it possible to do this without having two reference fields in C, like:

@ManyToOne private C parent;

Or do I need to have one reference for each implementation of C and do the assignment myself?

Answer 1

Nope. JPA doesn’t define persistence for fields/properties of interface types. JDO is the only persistence specification to allow that.

Only thing you could do is have a common base class, but that may be impossible with your model.