@OneToMany关系不保存子表中父级的主键

Question

让三个JPA实体。一个Person和两个一对多的关系。当我试图保存Person AD_P_ID和AC_P_ID外键总是为空。这些字段的预期值是人员ID。我究竟做错了什么？

1. Person.java：它包含与Account和Address Entity类的一对多关系

   @Entity
   @Table(name = "A2C_PERSON")
   class Person implements Serializable {
   
       private long id;
   
       private List<Account> acs;
   
       private List<Address> ads;
   
       @OneToMany(cascade=CascadeType.ALL, mappedBy = "person")
       public List<Account> getAccount() {
           return this.acs;
       }
   
       @OneToMany(cascade=CascadeType.ALL, mappedBy = "person")
       public List<Address> getAddress() {
           return this.ads;
       }
   }

2. Account.java

   @Entity
   @Table(name = "A2C_ACCOUNT")
   public class Account implements Serializable {
   
       private long id;
   
       private Person person;
   
       @ManyToOne(cascade=CascadeType.ALL, fetch = FetchType.LAZY)
       @JoinColumn(name = "AC_P_ID")
       public Person getPerson() {
           return this.person;
       }
   }

3. Address.java

   @Entity
   @Table(name = "A2C_ADDRESS")
   public class Address implements Serializable {
   
       private long id;
   
       private Person person;
   
       @ManyToOne(cascade=CascadeType.ALL,fetch = FetchType.LAZY)
       @JoinColumn(name = "AD_P_ID")
       public Person getPerson() {
           return this.person;
       }
   }

保存此人的代码：

Person p = new Person();

Account ac1 = new Account();
Account ac2 = new Account();
List<Account> acList = new ArrayList<>();
acList.add(ac1);
acList.add(ac2)

Address ad1 = new Adddress();
Address ad2 = new Adddress();
List<Address> adList = new ArrayList<>();
acList.add(ad1);
acList.add(ad2)

p.setAcs(acList);
p.setAds(adList);

personRepo.save(p);

Answer 1

对于每个Address和Account实体，您需要设置Person实体。这是必需的，以便hibernate在子节点中保存id：

Person p = new Person();

Account ac1 = new Account();
ac1.setPerson(p);  
List<Account> acList = new ArrayList<>();
acList.add(ac1);

Address ad1 = new Adddress();
ad1.setPerson(p);
List<Address> adList = new ArrayList<>();
acList.add(ad1);

Answer 2

@JoinColumn表示关系的所有者。

“MappedBy”表示反面。

所以：

@OneToMany(mappedBy = "parent")
private Collection<Child> childCollection;

不会为其子项设置父引用。这是你的情况。您可以像Maciej一样手动设置它，但它会添加一些样机代码。

要自动设置对其子项的父引用，您必须按以下方式定义关系的所有者。

@OneToMany(cascade = CascadeType.ALL)
@JoinColumn
private Collection<Child> childCollection;