SecondaryTable可以是一对多关系吗?

问题描述 投票:0回答:1

当前,我具有以下数据库结构:

+----------------+             +-----------------------+
|Person          |             |LegalGuardian_Person   |
|----------------+             |-----------------------+
|personId, int   |             |legGuard_person_id, int|
|name, varchar   |             |represented_person, int|
|surname, varchar|             |representative, int    |
+----------------+             +-----------------------+

presentated_person和代表都引用不同的人。现在,我尝试使用@SecondaryTable或@OneToOne来“加入”这些实体,以便我可以通过personId找出合法监护人是谁。

例如,玛丽亚和迈克尔是约翰的法定监护人:

personId: 1
name: Maria
surname: Doe
legalGuardian: []

personId: 2
name: Michael
surname: Doe
legalGuardian: []

personId: 3
name: John
surname: Doe
legalGuardian: [Maria, Michael]

到目前为止,我一直这样尝试,但是我总是得到一个空的列表:

@OneToMany(fetch = FetchType.EAGER)
@JoinTable(name = "LegalGuardian_Person",
joinColumns = @JoinColumn(name = "represented_person"),
inverseJoinColumns = @JoinColumn(name = "representative"))
private List<PersonRole> representatives;

[当我用@OneToMany(mappedBy="represented_person")尝试时,显然我得到了永无止境的结果。因此,我拥有Person实体,并尝试使用当前的personId查找represented_person并找回代表。

有办法吗?

java hibernate jpa hibernate-mapping
1个回答
0
投票

实现您所需要的一种方法是拥有OneToMany relationship between Person and LegalGuardian_Person,并且为了获得[[避免映射表,我们也可能拥有ManyToOne relationship between LegalGuardian_Person and Person

@Entity class LegalGuardian_Person { @Id@GeneratedValue(strategy = GenerationType.IDENTITY) private int id; @OneToOne private Person legGuard_person_id; @OneToOne private Person representative; @ManyToOne private Person represented_person; //getters and setters }
@Entity
public class Person {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int personId;
    private String name;
    private String surname;

    @OneToMany(mappedBy = "represented_person")
    Set<LegalGuardian_Person> legalGuardian_personSet;

    //getters and setters

    public static void main(String[] args) {
        Person Maria = new Person();
        Maria.setName("Maria");
        Maria.setSurname("Doe");

        Person Michael = new Person();
        Michael.setName("Michael");
        Michael.setSurname("Doe");

        Person John = new Person();
        John.setName("John");
        John.setSurname("Doe");

        {
            SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();
            Session session = sessionFactory.openSession();
            Transaction transaction = session.beginTransaction();

            session.save(Maria);
            session.save(Michael);
            session.save(John);

            LegalGuardian_Person John_LegalGuardian_Person = new LegalGuardian_Person();
            John_LegalGuardian_Person.setRepresented_person(John);
            John_LegalGuardian_Person.setLegGuard_person_id(Maria);

            session.save(John_LegalGuardian_Person);
            Set<LegalGuardian_Person> legalGuardian_personSet = new HashSet<>();
            legalGuardian_personSet.add(John_LegalGuardian_Person);

            John_LegalGuardian_Person = new LegalGuardian_Person();
            John_LegalGuardian_Person.setRepresented_person(John);
            John_LegalGuardian_Person.setLegGuard_person_id(Michael);

            session.save(John_LegalGuardian_Person);
            legalGuardian_personSet.add(John_LegalGuardian_Person);

            John.setLegalGuardian_personSet(legalGuardian_personSet);

            transaction.commit();
            session.close();
        }

        {
            SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();
            Session session = sessionFactory.openSession();

            Person person = session.get(Person.class, 3);
            person.legalGuardian_personSet.forEach(legalGuardian_person -> System.out.println(legalGuardian_person.getLegGuard_person_id().getName()));

            session.close();
        }
    }
}

由休眠和输出创建的表

Hibernate: create table LegalGuardian_Person (id integer not null auto_increment, legGuard_person_id_personId integer, representative_personId integer, represented_person_personId integer, primary key (id)) engine=MyISAM Hibernate: create table Person (personId integer not null auto_increment, name varchar(255), surname varchar(255), primary key (personId)) engine=MyISAM Hibernate: alter table LegalGuardian_Person add constraint FKoe3yay7hrvwic3od1f7ibdm0k foreign key (legGuard_person_id_personId) references Person (personId) Hibernate: alter table LegalGuardian_Person add constraint FKc7p7lx5e837i0blk0q1ukydnk foreign key (representative_personId) references Person (personId) Hibernate: alter table LegalGuardian_Person add constraint FKpkmx0g3ix2myf9py309ngwfaa foreign key (represented_person_personId) references Person (personId) Hibernate: insert into Person (name, surname) values (?, ?) Hibernate: insert into Person (name, surname) values (?, ?) Hibernate: insert into Person (name, surname) values (?, ?) Hibernate: insert into LegalGuardian_Person (legGuard_person_id_personId, representative_personId, represented_person_personId) values (?, ?, ?) Hibernate: insert into LegalGuardian_Person (legGuard_person_id_personId, representative_personId, represented_person_personId) values (?, ?, ?) Hibernate: alter table LegalGuardian_Person add constraint FKoe3yay7hrvwic3od1f7ibdm0k foreign key (legGuard_person_id_personId) references Person (personId) Hibernate: alter table LegalGuardian_Person add constraint FKc7p7lx5e837i0blk0q1ukydnk foreign key (representative_personId) references Person (personId) Hibernate: alter table LegalGuardian_Person add constraint FKpkmx0g3ix2myf9py309ngwfaa foreign key (represented_person_personId) references Person (personId) Hibernate: select person0_.personId as personId1_1_0_, person0_.name as name2_1_0_, person0_.surname as surname3_1_0_ from Person person0_ where person0_.personId=? Hibernate: select legalguard0_.represented_person_personId as represen4_0_0_, legalguard0_.id as id1_0_0_, legalguard0_.id as id1_0_1_, legalguard0_.legGuard_person_id_personId as legGuard2_0_1_, legalguard0_.representative_personId as represen3_0_1_, legalguard0_.represented_person_personId as represen4_0_1_, person1_.personId as personId1_1_2_, person1_.name as name2_1_2_, person1_.surname as surname3_1_2_, person2_.personId as personId1_1_3_, person2_.name as name2_1_3_, person2_.surname as surname3_1_3_ from LegalGuardian_Person legalguard0_ left outer join Person person1_ on legalguard0_.legGuard_person_id_personId=person1_.personId left outer join Person person2_ on legalguard0_.representative_personId=person2_.personId where legalguard0_.represented_person_personId=? Maria Michael
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