One to One relationship mapping JPA SpringBoot implementation error: ids for this class must be manually assigned before calling save()

Question

我正在尝试了解 JPA Spring 一对一映射的启动实现 classes，希望有人能给我提供清晰的图片。

一对一映射场景：Table foo 和 Table childfoo Foo 有 foo_id、foo_name、foo_place 列 childfoo 有 columnd foo_id(foo table 的外键), childfoo_name

这是我目前所做的 JPA 实体实现：

@Entity
@Data
@Table(name = "foo")
public class foo implements Serializable {

/**
 * 
 */
private static final long serialVersionUID = 1L;

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "foo_id")
private Integer fooId;

@OneToOne(cascade = CascadeType.ALL, fetch = FetchType.LAZY)
@JoinColumn(name="fooId")
private ChildFoo childFoo;
}

ChildFoo class

@Entity
@Data
@NoArgsConstructor
@EqualsAndHashCode(exclude ="foo")
@Table(name = "childfoo")
public class Childfoo implements Serializable {

    /**
     * 
     */
    private static final long serialVersionUID = -8142203085486540150L;
    
    @Id
    private Integer fooId;

    @OneToOne(cascade = CascadeType.ALL, optional = false, fetch = FetchType.LAZY)
    @PrimaryKeyJoinColumn(name = "foo_id", referencedColumnName = "fooId")
    private Foo foo;
    
    @Column(name="child_name")
     private String childName;

   }

我已经为 Foo 创建了一个存储库并且我正在使用 FooRepository.save(foo) 在控制器中保存数据。

添加 foo 和 childfoo 的控制器代码：

Foo foo = new Foo();
foo.set...

   ChildFoo childFoo = new ChildFoo();
        childFoo.setChildName("abc");
        childFoo.setFoo(foo);

foo.setChildFoo(childFoo);
fooRepository.save(foo);

但我收到错误消息：

此 class 的 ID 必须在调用 save() 之前手动分配。

Answer 1

从您的评论看来，您正在尝试使用 shared primary key strategy，其中 ChildFoo 也将使用 fooId 作为自己的主键。

如果是这样，那么我认为您需要更新一些 JPA 注释：

@Entity
@Data
@Table(name = "foo")
public class Foo implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "foo_id")
    private Integer fooId;

    @OneToOne(cascade = CascadeType.ALL, mappedBy = "foo")
    private ChildFoo childFoo;

}


@Entity
@Data
@NoArgsConstructor
@EqualsAndHashCode(exclude ="foo")
@Table(name = "childfoo")
public class ChildFoo implements Serializable {

    private static final long serialVersionUID = -8142203085486540150L;
    
    @Id
    @Column(name = "foo_id")
    private Integer fooId;

    @OneToOne(cascade = CascadeType.ALL, optional = false)
    @MapsId // primary key copied from Foo
    @JoinColumn(name = "foo_id")
    private Foo foo;
    
    @Column(name="child_name")
     private String childName;

}

并且您可能需要在关联和保存 ChildFoo 之前保存 Foo 的实例（从而生成共享 ID），但我认为一旦所有内容都被正确注释后就没有必要了。

说到注释，我只是从您的原始注释中删除了惰性提取类型以阐明更新。您应该能够毫无问题地包含它们。

其他有用的链接： Shared primary key with JPA and Spring Boot OneToOne shared primary key - JPA2.0 updates

One to One relationship mapping JPA SpringBoot implementation error: ids for this class must be manually assigned before calling save()

One to One relationship mapping JPA SpringBoot implementation error: ids for this class must be manually assigned before calling save()

java

spring-boot

jpa

one-to-one

spring-boot-jpa