JPA entity with a interface attribute, is it possible?

Question

I have the following entity:

@Entity
public class TestCaseStep implements JPAEntity<Integer> {

        ...

    @Column(name="STEP_NUMBER")
    private Integer stepNumber;

    @Enumerated(EnumType.STRING)
    @Column(name="ACTION")
    private Action action;

    **@ManyToOne
    @JoinColumn(name="connector")
    private ScriptItem connector;**

My attribute ScriptItem is a interface for 3 other classes. Is it possible to configure JPA to set the correct class id in runtime execution?

Other resources:

public interface ScriptItem {

    String getValue();
    ScriptItemType getType();
}

@Entity
@Table(name="DAT_FEED_XML")
public class FeedXml implements JPAEntity<Integer>, ScriptItem {
    ...
}

@Entity
@Table(name="DAT_DB_STMT")
public class DbStatement implements JPAEntity<Integer>, ScriptItem {
       ...
}

Which annotations should I use to let JPA understand that I want to save the id of one of the 3 classes?

Thanks in advance,

Answer 1

It is really a good idea but unfortunately directly mapping interfaces as an entity attribute is not supported by JPA.

You can only map top level classes directly annotated with @Entity. This top level class may implement an interface though.

This feature has been requested and discussed for a long time.

Also take a look at this and this.

Depending on what you're trying to accomplish, @Inheritance annotation with table-per-class strategy could be an option.

I hope it helps.