java - 乘以 ID 映射抛出 BaseEntity

Question

我正在通过 Hibernate 映射类，并且需要为 Relationship 映射多个 ID。所有 ID 均从 BaseEntity 扩展。如何为 Relationship 实现多个 ID 映射，其中包含数据库中 User 的外键？

基本上，Relationship 中的字段 userIdOne 和 userIdTwo 必须包含发送请求的用户 ID。

User从BaseEntity扩展自己的ID。

每次运行它时 - 都会出现错误:

This class [class com.mylov.springsocialnetwork.model.Relationship] does not define an IdClass

    @Getter
    @Setter
    @NoArgsConstructor
    @AllArgsConstructor
    @MappedSuperclass
    @EqualsAndHashCode
    public class BaseEntity implements Serializable {
        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        private Long id;

    }


    @Builder
    @Getter
    @Setter
    @NoArgsConstructor
    @AllArgsConstructor
    @EqualsAndHashCode(exclude = {"posts"}, callSuper = false)
    @Entity
    public class User extends BaseEntity {
        private String userName;
        private String realName;
        private String email;
        private String phoneNumber;
        private LocalDate birthDate;

        @OneToMany(cascade = CascadeType.ALL, mappedBy = "userPosted")
        private Set<Post> posts = new HashSet<>();
        private String password;

        public User(Long id, String userName, String realName, String email, String phoneNumber, LocalDate birthDate,
                    Set<Post> posts, String password) {
            super(id);
            this.userName = userName;
            this.realName = realName;
            this.email = email;
            this.phoneNumber = phoneNumber;
            this.birthDate = birthDate;
            this.posts = posts;
            this.password = password;
        }
    }


    @Builder
    @Getter
    @Setter
    @NoArgsConstructor
    @AllArgsConstructor
    @Entity
    public class Relationship implements Serializable {

        //@Id not working
        private Long userIdFrom;
        //@Id
        private Long userIdTo;

        @Enumerated(value = EnumType.STRING)
        private RelationshipStatus status;
        private LocalDate friendsRequestDate;
    }

Answer 1

您似乎希望在两个不同的用户之间建立关系。这意味着每个 Relationship 都是它自己的对象/实体，并且应该有自己的 @Id (与用户 ID 无关)。构成此关系的每个User的链接应映射为外键(可能是@ManyToOne和@JoinColumn )。

例如:

@Entity
public class Relationship implements Serializable {

    @Id
    private Long relationshipId;

    @ManyToOne(...)
    @ForeignKey(name="FK_USER_ONE") //for generation only, it isn't strictly required
    @JoinColumn(name="from")
    private Long userIdFrom;

    @ManyToOne(...)
    @ForeignKey(name="FK_USER_TWO") //for generation only, it isn't strictly required
    @JoinColumn(name="to")
    private Long userIdTo;

    @Enumerated(value = EnumType.STRING)
    private RelationshipStatus status;
    private LocalDate friendsRequestDate;
}

<小时/>

编辑:不需要指定 @ForeignKey 注释。如果数据库表是自动生成的(可以用于测试，但在生产中通常不是您想要的)，则将使用它们，并将相应地在表上创建 FOREIGN KEY 约束，但 JPA 映射将没有它也可以正常工作，因为它从您定义的模型中获取关系，而不是从数据库本身。