如何在复合主键中使用外键？

Question

我想用hibernate 创建一个composite primary key。通常我会选择@IdClass。

但这次我想在复合主键中也使用foreign key。

问题：这可能吗？

例子：

@Entity
class Person {
    long id;
}

class CarPK implements Serializable {
    private int code;
    private String name;

    public CarPK(int code, String name) {
        this.code = code;
        this.name = name;
    }
}

@Entity
@IdClass(CarPK.class)
class Car {
    @Id
    private int code;

    @Id
    private String name;

    //can I also mark "person.id" with @Id?
    @ManyToOne
    @JoinColumn(name = "fk_person_id", foreignKey = @ForeignKey(name = "fk_person"))
    private Person person; //assume car is shared
}

人员参考将在数据库中显示为fk_person_id。是否也可以将此列添加到car 表的primary key 中？

所以我会变得类似于：CONSTRAINT car_pkey PRIMARY KEY (code, name, fk_person_id)?

---

更新：

@ManyToOne
@JoinColumn(name = "id")
private Person person;

结果：Property of @IdClass not found in entity path.to$Car: id

Answer 1

是的，您可以将@Id 添加到连接列，但您必须使用IdClass 中的密钥类型。在我当前的项目中，我正在做同样的事情。

@Entity
@IdClass(MyIdClass.class)
public class MyObject {

    @Id
    private String key;

    @Column
    @Lob
    private String value;

    @ManyToOne(cascade = CascadeType.PERSIST)
    @Id
    @JoinColumn(name = "id")
    private MyOtherObject otherObject;
...

和

public class MyIdClass implements Serializable {

    private long otherObject;
    private String key;

...

MyOtherObject.id 在这种情况下是 long。