Question

当我试图拯救人时，它不会保存任何人或城市。我不想保存或更新City对象。我只想更新/删除joinColumn。有没有办法做到这一点？

Person person = new Person();
person.setCities(...);
personDAO.save(person);



public class Person{

    @OneToMany(fetch = FetchType.EAGER)
    @JoinColumn(name = "city_id")
    private List<City> cities;

}


public class City{
    @Id
    @Column(name = "city_id")
    @GeneratedValue(generator = "system-uuid")
    @GenericGenerator(name = "system-uuid", strategy = "org.hibernate.id.UUIDGenerator")
    private String cityId;

}

Answer 1

首先在城市一侧定义@ManyToOne映射：

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

然后添加mappedBy属性并删除@JoinColumn：

@OneToMany(fetch = FetchType.EAGER, mappedBy = "person")
private List<City> cities;

当你保存/更新时，你必须在依赖关系的两边设置实体：

Person person = new Person();
person.setCities(...);

for(City city: cities){
   city.setPerson(person);
}  

personDAO.save(person);

同样适用于删除..您必须删除双方的实体引用。

如何在没有任何级联的情况下定义单向OneToMany JPA关系？

1 个答案: