hibernate - 具有反向外键的单向@OneToOne

Question

我们想使用不在主表中但在从表中的外键创建单向@OneToOne映射。通过提供以下Java代码，Hibernate尝试在表product_ID中找到product列，但在productimage中找不到。是否可以使其仅对注释进行修改？

该示例中删除了所有不必要的字段和列。

JPA实体:

@Entity
public class Product {

    @Id
    @Column(name = "ID", unique = true)
    private String id;

    // this doesn't work
    @OneToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL, orphanRemoval = true)
    @JoinColumn(name = "product_ID", nullable = false)
    private ProductImage productImage;

    // this works, but we want one-to-one
    // @OneToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL, orphanRemoval = true)
    // @JoinColumn(name = "product_ID", nullable = false)
    // private List<ProductImage> productImages;

    // getters/setters omitted
}

@Entity
public class ProductImage {

    @Id
    @Column(name = "ID", unique = true)
    private String id;

    @Column
    @Lob
    private Blob data;

    // getters/setters omitted
}

数据库表:

CREATE TABLE `product` (
  `ID` varchar(255) NOT NULL,
  PRIMARY KEY (`ID`)
)

CREATE TABLE `productimage` (
  `ID` varchar(255) NOT NULL,
  `data` longblob NOT NULL,
  `product_ID` varchar(255) NOT NULL,
  PRIMARY KEY (`ID`),
  KEY `FK_123` (`product_ID`),
  CONSTRAINT `FK_123` FOREIGN KEY (`product_ID`) REFERENCES `product` (`ID`)
)

Answer 1

JPA实体，更多关于 @PrimaryKeyJoinColumn :

@Entity
public class Product {
    @Id
    private String id;

    @PrimaryKeyJoinColumn
    @OneToOne(orhanRemoval = true)
    private ProductImage image;
}

@Entity
public class ProductImage {
    @Id
    private String productId; // this will be foreign key as well as primary

   //other properties goes here
}

数据库表:

CREATE TABLE product (
    id VARCHAR PRIMARY KEY
);

CREATE TABLE product_image (
    product_id VARCHAR PRIMARY KEY REFERENCES product(id)
    -- other columns goes here
);