JPA：保留外键约束的问题

我有两个实体：

客户实体

@Entity
public class Customer {

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;

private String name;

@OneToMany(mappedBy="customer", cascade=CascadeType.ALL)
private List<Facility> facilities;

//Setter and Getter for name and facilities

public void addFacility(Facility facility){
    this.facilities.add(facility);
}
}

所以我主要是这样做的

    Customer customer = new Customer();
    customer.setName("Wake Forest University");
    Facility facility = new Facility();
    facility.setName("Tom Cruise");
    EntityManager entityManager = Persistence.createEntityManagerFactory("EntityClassPU").createEntityManager();
    entityManager.getTransaction().begin();
    customer.addFacility(facility);
    entityManager.persist(customer);
    entityManager.getTransaction().commit();

---

Wake Forest University

已成功插入

Customer

，并且

Tom Cruise

已成功插入

Facility

，但是在

Facility

内部，

Customer\u FK

值为空，这表明我无法持久保存外键约束。我做错了什么？

您的

客户

和

设施

之间的关系是双向关联，您必须管理关联的双方。您可以手动执行此操作，但我建议使用

addFacility（）

方法执行此操作：

public void addFacility(Facility facility){
    if (this.facilities == null) { 
        this.facilities = new ArrayList<Facility>();
    } 
    this.facilities.add(facility);
    facility.setCustomer(this); // that's the part you're currently missing
}

公共设施（设施）{
如果（this.facilities==null）{
this.facilities=new ArrayList（）；
} 
本.设施.新增（设施）；
facility.setCustomer（this）；//这是您当前缺少的部分
}

@PascalThivent:你能抽出几分钟帮我解决这个问题吗>>

public void addFacility(Facility facility){
    if (this.facilities == null) { 
        this.facilities = new ArrayList<Facility>();
    } 
    this.facilities.add(facility);
    facility.setCustomer(this); // that's the part you're currently missing
}