Identity Crisis: JPA @Id

Who am I?

Allow me to show you a simple JPA mapping,

@MappedSuperclass
public class Domain implements Serializable {
    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "ID_SEQ")
    private Integer id;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }
}

Do you see the thorny issue here?

Look again.

Yes, you're right - the setter method!

    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "ID_SEQ")

    public void setId(Integer id) {
        this.id = id;
     }

In my view, the setter method should not be there at all as id property is marked as "sequence". How often do you invoke setId(Integer) method? I believe rarely or almost never.

A question emerges from the back of your mind - "But I need that for my unit test?!".

If you populate this property yourself, then there's something wrong with your unit test and I strongly suggest that you rethink the way you write your test code.

I admit I've done this before many times. You are not alone my friend.

"Who is it that can tell me who I am?"