OneToMany JPA关系和AbstractClass中的targetEntity

Question

I'm currently using JPA (EclipseLink) but I'm stuck because of the targetEntity parameter for a OneToMany relation.

@Entity
@Table(name = "INVENTORY")
public class InventoryJPA implements IInventory {

    /**
     * Unique identifier of the inventory
     */
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "ID")
    private int id;

    /**
     * The list of resources avalible in the inventory.
     */
    private transient Map<Resource, Integer> resources = null;

    /**
     * The list of items in the inventory.
     */
    @OneToMany( targetEntity = AbstractItemJPA.class,
            cascade = CascadeType.ALL)
    private List<IItem> items = null;

I have an AbstractItemJPA class which impl. a IItem interface. And others Abstract classes which extend AbstractItemJPA.

This is a example :

@MappedSuperclass
public abstract class AbstractControlItemJPA extends AbstractItemJPA implements IControlItem

It seems that EclipseLink don't want an AbstractClass for the targetEntity parameter.

@OneToMany( targetEntity = AbstractItemJPA.class,
                cascade = CascadeType.ALL)
        private List<IItem> items = null;

Is there a solution for this ?

Thanks for all !

Answer 1

You didn't give us the way you defined your AbstractItemJPA.

Nevertheless, a class annotated with @MappedSuperclass is not an entity. It is only a class used to share mapping information with its children.

Thus you can't create an association to this class. Only an association to an entity can be created.

You should ask yourself if you really need such a complex hierarchy of classes. Keep your entities model simple and keep control on how the hierarchy of your classes will be stored in table (one table or several tables ?).