[hibernate-dev] Can a transient attribute be overridden to be persistent in a subclass?

[Gail Badner]

I *think* the following is valid, but I need confirmation. This mapping
does seem to work for Hibernate.

A transient attribute, Employee#title, gets overridden as a persistent
attribute, Editor#title, stored in a column named "e_title".

Writer#title is also transient, but Writer#group uses the same "e_title"
column as a foreign key. That foreign key value is used to populate
Writer#title.

@Entity
@Table(name="Employee")
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name="department")
public abstract class Employee {
    private String name;
    private String title;

    @Id
    public String getName() {
        return name;
    }

    @Transient
    public String getTitle() {
        return title;
    }

    protected void setName(String name) {
        this.name = name;
    }

    protected void setTitle(String title) {
        this.title = title;
    }
}

@Entity
public class Editor extends Employee {
    @Column(name = "e_title")
    public String getTitle() {
        return super.getTitle();
    }

    public void setTitle(String title) {
        super.setTitle( title );
    }
}

@Entity
public class Writer extends Employee {
    private Group group;

    @ManyToOne(optional = false)
    @JoinColumn(name = "e_title")
    public Group getGroup() {
        return group;
    }

    public void setGroup(Group group) {
        this.group = group;
        setTitle( group.getName() );
    }
}

In 4.2, the above mapping worked with Employee#title being persistent, but
does not work in 5.3.

Section 2.2 Persistent Fields and Properties of the spec says:

"Entity subclasses may override the property accessor methods. However,
portable applications must not override the object/relational mapping
metadata that applies to the persistent fields or properties of entity
superclasses."

Would overriding a transient attribute be portable? If not, is that
something Hibernate would/should support?

Thanks,
Gail