JPQL 查询/JPA/Spring 引导更新多对多的最佳实践table

Question

我有一个 user table 和一个 city table 并且我有一个连接 table users_cities（列：id， user_id、city_id）。一个用户可以关注多个城市。从客户端我发送了一个 cityIds 的数组。有些可能是新的，有些可能仍处于选中状态，有些可能已被取消选择。

用数据更新 users_cities table 的最佳做法是什么？我应该只删除那个特定 userId 的所有内容并插入新数组还是...？~

此外，一个 delete 和 insert 如何批量处理数据，供多对多参考？！

@Getter
@Setter
@NoArgsConstructor
@ToString
@Accessors(chain = true)
@Entity
@Table(name = "users")
public class User {

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

    @Column(unique = true)
    private String email;

    private String password;

    private Boolean isGuest;

    @ManyToMany(fetch = FetchType.EAGER)
    private Set<Role> roles;

    @ManyToOne()
    @JoinColumn(name = "country_following_id")
    private Country countryFollowing;

    @ManyToMany()
    private Set<City> citiesFollowing;

    @ManyToMany()
    private Set<Offer> offersFollowing;

}

和

@Getter
@Setter
@NoArgsConstructor
@ToString
@Accessors(chain = true)
@Entity
@Table(name = "cities")
public class City {

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

    private String countryCode;
    private String name;

    @Latitude
    private Double latitude;
    @Longitude
    private Double longitude;


}

Answer 1

Should I just delete everything for that particular userId and insert the new array

既然连接用户和城市的关系没有自己的身份，这听起来很合理

Also, how does one delete and repsectively insert the data in bulk, for a many to many reference?

只需清除 User.citiesFollowing 集合并重新填充它（提示：由于您已准备好 cityIds，您可以使用 EntityManager.getReference() 加载城市）

JPQL 查询/JPA/Spring 引导更新多对多的最佳实践table

JPQL query / JPA / Spring boot best practice of updating many to many table

jpa

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