Hibernate删除多到多个惰性集合

Question

我的实体类是：

@Entity
public class User implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(unique = true, nullable = false)
    private Long id;

    @Temporal(TemporalType.TIMESTAMP)
    @Column(name = "dt_creation", nullable = false)
    private Date dtCreation;

    @Temporal(TemporalType.TIMESTAMP)
    @Column(name = "dt_maj", nullable = false)
    private Date dtMaj;

    // bi-directional many-to-one 
    @OneToMany(mappedBy = "quality", cascade = CascadeType.ALL, orphanRemoval = true)
    private Set<RQulityUser> RQualityUser;


@Entity
public class RQualityUser implements Serializable {

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private Long id;

    @Temporal(TemporalType.TIMESTAMP)
    @Column(name = "dt_creation", nullable = false)
    private Date dtCreation;

    @Temporal(TemporalType.TIMESTAMP)
    @Column(name = "dt_maj", nullable = false)
    private Date dtMaj;

    // bi-directional many-to-one association to Questionnaire
    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "fk_user", updatable = false, nullable = false)
    private User user;

    // bi-directional many-to-one association to QualitePersonne
    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "cd_quality_user", updatable = false, nullable = false)
    private Quality quality;

当我得到一个用户，并且我试图清除RQualityUser列表时，我不工作：

 User user = em.getByid(11);
 user.getRQualityUserList().clear();

Hibernate不删除关系表中的记录吗？

Answer 1

“延迟加载”意味着，只有当您第一次实际访问实体时，才会加载实体。

当你做的时候

user.getRQualityUserList() // Still contains nothing.

因此，您正在清除空列表，然后当您使用该列表时，将从DB调用数据。

Answer 2

如果你这么做

User user = em.getByid(11);
user.getRQualityUserList().clear();

对于打开的持久上下文和事务内部，Hibernate应该删除记录。

如果你没有交易，你应该使用它。

如果使用封闭的持久上下文执行clear()，则应更新user以删除记录。