Question

I have JPA code that compiles fine in eclipse Helios and works fine in production. But in a newer version of eclipse, I am getting the error “ID class should not be mapped” when using the annotation @IdClass from javax.persistence.* package.

@Entity
@IdClass(RetailLocationPK.class)  // Generates "ID class should not be mapped" error
@Table(name="loc_rtl_loc")
public class RetailLocation implements Serializable {
    @Id
    @Column(name="organization_id")    
    private int organizationId;

    @Id
    @Column(name="rtl_loc_id")
    private int rtlLocId;
...
}

Then in RetailLocationPK.java I have:

@Embeddable
public class RetailLocationPK implements Serializable {
    //default serial version id, required for serializable classes.
    private static final long serialVersionUID = 1L;
    @Column(name="organization_id")
    private int organizationId;

    @Column(name="rtl_loc_id")
    private int rtlLocId;

    public RetailLocationPK() {
    }
    ...
}

Finally, in persistence.xml, I have:

<persistence-unit name="taxPu" transaction-type="JTA">
    <class>tbss.persist.RetailLocation</class>
    <class>tbss.persist.RetailLocationPK</class>
    ...
</persistence-unit>

I have turned off the error notification for now, but why does this happen?

Answer 1

I’m not sure that it shouldn’t be, but @IdClass (unlike @EmbeddedId) definitely doesn’t have to be @Embeddable and mapped with <class>.