Question

我有两个@OneToOne关系的实体：

@Entity
public class User implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id_user")
    private Long id;

    @OneToOne(cascade = CascadeType.MERGE, orphanRemoval=true)
    @JoinColumn(name = "id_details")
    private UserDetails details;
//...username, password, email
}

@Entity
public class UserDetails implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id_user_details")
    private Long id;
//...firstname, lastname, address
}

首先，我使用UserDetails保存用户：

public class Main {
    public static void main(String[] args) {
        EntityManagerFactory emf = Persistence.createEntityManagerFactory("pu");
        EntityManager em = emf.createEntityManager();

        em.getTransaction().begin();
        UserDetails details = new UserDetails("John", "Doe", "NYC 11");
        User user = new User("uname", "pass", "mail", details);
        em.merge(user);
        em.getTransaction().commit();

        em.close();
        emf.close();
    }
}

一切正常，因为有级联MERGE，因此两个实体都被保存。当我运行另一个班级时：

public class MainUpdate {
    public static void main(String[] args) {
        EntityManagerFactory emf = Persistence.createEntityManagerFactory("pu");
        EntityManager em = emf.createEntityManager();

        User user = em.find(User.class, 1L);
        user.setDetails(null);

        em.getTransaction().begin();
        em.merge(user);
        em.getTransaction().commit();

        em.close();
        emf.close();
    }
}

我预计用户中的id_details将在数据库中设置为null（它是）但是因为有orphanRemoval = true我还希望孤儿行将从userdetails表中删除但不是。

当我设置CascadeType PERSIST而不是MERGE时，有趣的是删除了孤儿。有人可以解释为什么PERSIST与orphanRemoval一起工作但是MERGE没有吗？

GitHub回购：https://github.com/slwch/onetoone-orphan

使用Hibernate 5.0.6和4.1.8进行测试

与Cascade PERSIST和MERGE

0 个答案: