JPA / Hibernate - 如何获取EmbeddedId？

Question

I have the following entity:

@Entity(name = "game_users")
public class GameUser {

    private GameUsersPK primaryKey;

    @EmbeddedId
    public GameUsersPK getPrimaryKey() {
        return primaryKey;
    }
    ...
}

With the following PK:

@Embeddable
public class GameUsersPK implements Serializable {
    @ManyToOne
    private Game game;

    @ManyToOne
    private User user;
    ...
}

When I query for a GameUser by executing:

GameUser gameUser = em.createQuery("from game_users", GameUser.class).setMaxResults(1).getSingleResult();

I notice Hibernate is executing two queries - one from game_users and one from games left outer join users .

Can I make Hibernate fetch all entities in one query - from game_users, games, users ?

Thanks.

Answer 1

select gu from GameUser gu
left join fetch gu.primaryKey.game
left join fetch gu.primaryKey.user

Read the Hibernate documentation about HQL and associations .