ManyToMany关系删除所有实体
ManyToMany关系删除所有实体
提问于 2019-06-21 03:22:47
我有两个实体，user和movies。他们有很多的双向关系。我的问题是，当我通过我的控制器删除一部电影时，它也会删除所有与该电影实体相关的内容。我的用户和此用户角色以及电影实体。我该怎么做，当删除电影实体时，从表中删除它，并保留用户的角色，而不是全部删除它们。
@Data
@ToString
@EqualsAndHashCode
@Entity
@Table(name = "movies")
public class Movie {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
@Column(name = "title")
private String title;
@Column(name = "description")
private String description;
@Column(name = "release_date")
@Temporal(TemporalType.DATE)
private Date release_date;
@Column(name = "country")
private String country;
@Column(name = "category")
private String category;
@ManyToMany(mappedBy = "movies")
@ToString.Exclude
@EqualsAndHashCode.Exclude
private Set<User> users = new HashSet<>();@Data
@ToString
@Entity
@Table(name = "users")
public class User {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
@Column(name = "username")
private String username;
@Column(name = "password")
private String password;
@Transient
private String confirmPassword;
@ManyToMany(cascade = CascadeType.ALL)
@JoinTable(name = "users_roles", joinColumns = {@JoinColumn(name = "user_id", referencedColumnName = "id")},
inverseJoinColumns = {@JoinColumn(name = "role_id", referencedColumnName = "id")})
@ToString.Exclude
@EqualsAndHashCode.Exclude
private Set<Role> roles = new HashSet<>();
@ManyToMany(cascade = CascadeType.ALL)
@JoinTable(name = "users_movies", joinColumns = {@JoinColumn(name = "user_id", referencedColumnName = "id")},
inverseJoinColumns = {@JoinColumn(name = "movie_id", referencedColumnName = "id")})
@ToString.Exclude
@EqualsAndHashCode.Exclude
private Set<Movie> movies = new HashSet<>();回答 2
Stack Overflow用户
发布于 2019-06-21 21:57:20
问题解决了，我没有使用mappedBy，而是在电影实体中添加了一个JoinTable注释，现在它可以正常工作了。
Stack Overflow用户
发布于 2019-06-21 21:19:19
好吧，我不得不猜测您的Role实体是什么样子的，所以要包含完整的示例。您没有指定是使用Spring-Data-Jpa还是仅使用Jpa，所以谁知道呢。编辑:在您的示例中，您最终澄清了您使用的是spring-data-jpa，但概念与本文中的概念是相同的。
@Data
@ToString
@Entity
@Table(name = "roles")
public class Role {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
@ManyToMany(mappedBy="roles")
@ToString.Exclude
@EqualsAndHashCode.Exclude
private Set<User> users = new HashSet<>();
}并使用
tx.begin();
User u1 = new User();
Role r1 = new Role();
u1.setRoles(Collections.singleton(r1));
Movie m1 = new Movie();
m1.setDescription("movie 1");
Movie m2 = new Movie();
m2.setDescription("movie 2");
u1.setMovies(Stream.of(m1, m2).collect(Collectors.toSet()));
em.persist(u1);
tx.commit();
// now to query
em.clear();
tx.begin();
User u = em.createQuery("from User u left outer join fetch u.movies where u.id = 1", User.class).getSingleResult();
Movie m = u.getMovies().stream().filter(mv->mv.getDescription().equals("movie 1")).findFirst().get();
u.getMovies().remove(m);
em.remove(m);
tx.commit();这将创建日志
create table users (id bigint generated by default as identity (start with 1), password varchar(255), username varchar(255), primary key (id))
create table users_movies (user_id bigint not null, movie_id bigint not null, primary key (user_id, movie_id))
create table users_roles (user_id bigint not null, role_id bigint not null, primary key (user_id, role_id))
alter table users_movies add constraint FKt4hasm7tvj0vor58ql33xptjy foreign key (movie_id) references movies
alter table users_movies add constraint FKhhj9vi206o88q0typfntk3fek foreign key (user_id) references users
alter table users_roles add constraint FKj6m8fwv7oqv74fcehir1a9ffy foreign key (role_id) references roles
alter table users_roles add constraint FK2o0jvgh89lemvvo17cbqvdxaa foreign key (user_id) references users
insert into users (id, password, username) values (default, ?, ?)
insert into movies (id, category, country, description, release_date, title) values (default, ?, ?, ?, ?, ?)
insert into movies (id, category, country, description, release_date, title) values (default, ?, ?, ?, ?, ?)
insert into roles (id) values (default)
insert into users_movies (user_id, movie_id) values (?, ?)
insert into users_movies (user_id, movie_id) values (?, ?)
insert into users_roles (user_id, role_id) values (?, ?)
select user0_.id as id1_2_0_, movie2_.id as id1_0_1_, user0_.password as password2_2_0_, user0_.username as username3_2_0_, movie2_.category as category2_0_1_, movie2_.country as country3_0_1_, movie2_.description as descript4_0_1_, movie2_.release_date as release_5_0_1_, movie2_.title as title6_0_1_, movies1_.user_id as user_id1_3_0__, movies1_.movie_id as movie_id2_3_0__ from users user0_ left outer join users_movies movies1_ on user0_.id=movies1_.user_id left outer join movies movie2_ on movies1_.movie_id=movie2_.id where user0_.id=1
delete from users_movies where user_id=? and movie_id=?
delete from movies where id=?页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/56692623
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