JPA Spring boot在删除时删除参考？

Question

Im使用JPA、MySQL和Spring boot

我一辈子都搞不清楚如何应用级联，文档似乎没有应用我的意图：

例如。https://hellokoding.com/deleting-data-with-jpa-hibernate/使用CascadeType。ALL或CascadeType。删除父实体时，删除子实体的REMOVE属性。它们可以在@OneToOne、@OneTo很多、@ManyToOne和@ManyTo很多上使用

^我不想删除子实体我只想删除引用

我猜这种关系是多对多的？

many users can have many modules
many modules can have many users

如何通过级联注释应用此功能？

when a user is deleted the module is not

when a module is deleted its reference is removed from user

when a user is added a module is not

when a module is added a user is not

当前实体：

@Entity
@Table(name = "module")
public class Module {
    @Id
    @GeneratedValue( strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;
    @ManyToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL, mappedBy = "modules")
    private Set<User> users;

Answer 1

您可以指定“孤立删除”（OrphanRemoving），如果为true-从数据库中删除，如果为false-不删除

对于许多人

@ManyToMany
@Cascade(value = org.hibernate.annotations.CascadeType.DELETE_ORPHAN)
private Set<User> users;

对于OneToMany

@OneToMany(mappedBy = "topic", cascade = CascadeType.ALL, orphanRemoval = true)
private Set<User> users;