Spring 启动 JPA 复合外键映射

Question

我在为某些实体设置 jpa 映射时遇到问题。下面是我要实现的场景。

有 3 个表：

Users：存储用户信息。（自动生成的 ID 是主键）
Posts：存放公司发布的Feed。（自动生成的 ID 是主键）
Likes：存储用户喜欢的Feed。 ( User-Id, Post-Id as composite Primary key )

下面是我尝试实现的代码，但它不起作用

@Entity(name = "likes")
@IdClass(LikesId.class)
public class Likes {

    @Id
    @ManyToOne(optional = false)
    @JoinColumn(name = "post_id")
    private Post post;

    @Id
    @ManyToOne(optional = false)
    @JoinColumn(name = "user_id")
    private User user;

    @UpdateTimestamp
    private Date timestamp;

    public Like (Post post, User user){
        this.setPost(post);
        this.setUser(user);
    }

}

下面是复合键的 IdClass :

@NoArgsConstructor
@AllArgsConstructor
@EqualsAndHashCode
public class LikesId implements Serializable {

    @ManyToOne(optional = false)
    @JoinColumn(name = "post_id")
    private Post post;

    @ManyToOne(optional = false)
    @JoinColumn(name = "user_id")
    private User user;

}

我在调用 saveAndFlush 时遇到以下错误：

java.lang.IllegalArgumentException: Can not set com.app.models.post.Post field com.app.models.likes.LikesId.post to java.lang.Long

Answer 1

您的 ID class 应如下所示。

@NoArgsConstructor
@AllArgsConstructor
@EqualsAndHashCode
public class LikesId implements Serializable {

    private Long postId;

    private Long userId;

}

Spring 启动 JPA 复合外键映射

Spring boot JPA composite foreign key mapping

foreign-keys

composite-key

composite-primary-key

spring-boot

spring-boot-jpa