Use an enum as ID in JPA-CodePudding

I'm trying to create an entity like this:

public class Entity {

    @Id
    @Column(name = "id")
    private EntityId id;

    @RequiredArgsConstructor
    public enum EntityId {

        A("a"),
        B("b"),
        C("c"),
        D("d");

        @Getter
        private final String id;

    }

}

And I have its corresponding repository:

public interface EntityRepository extends JpaRepository<Entity, Entity.EntityId> {
}

But executing EntityRepository#findAll throws the following:

org.springframework.dao.DataIntegrityViolationException: could not execute query; SQL [select entity0_.id as id_1_2_ from entity entity0_];

...

Caused by: org.hibernate.exception.DataException: could not execute query

...

Caused by: org.h2.jdbc.JdbcSQLDataException: Data conversion error converting "b" [22018-200]

...

Caused by: java.lang.NumberFormatException: For input string: "b"

I also created the corresponding AttributeConverter<Entity.EntityId, String>, but I don't know what else to do... FYI if I remove Entity.EntityId#id and use @Enumerated(STRING) it works perfectly, but I need that property...

UPDATE:

To clarify, the table's id is a string, so using enum's ordinal is not possible. Also, it is not possible to use enum's name since the table is populated with a, b, c and d; not A, B, C or D.

CodePudding user response：

You cannot use the id of the enum as the primary key. That's not possible.

The only thing you can do is to use the enum string value.

@Id
@Enumerated(EnumType.STRING)
private EntityId id;

The problem is that enums are singleton and immutable values. So to make your example work it would be necessary to have a setter the enum.