Hibernate:如何在 Annotation 的一个连接表中加入三个 3 表? [英] Hibernate: How to Join three 3 tables in one join table in Annotation?

问题描述

你能帮我如何用一张普通的连接表连接三个表吗?我有 USER、APPLICATION 和 ROLE 表.我希望他们的 ID 加入一个名为 USER_APP_ROLE(user.ID, application.ID, role.ID) 的表中.

Can you please help me how to join three tables with one common join table? I have USER, APPLICATION, and ROLE tables. And I want thier IDs to be joined in a table named USER_APP_ROLE(user.ID, application.ID, role.ID).

当我在多对多连接中删除应用程序或角色表时，我的代码正在运行.

When I remove either Application or Role tables in Join Many to Many my code is working.

我已经完成了以下代码:

I have done the following codes:

用户.java

@ManyToMany (targetEntity=Role.class)
@JoinTable(name="USER_APPLICATION_ROLE",
    joinColumns=@JoinColumn(name="USER_ID"),
    inverseJoinColumns=@JoinColumn(name="ROLE_ID"))

private Collection<Role> roles;

@ManyToMany (targetEntity=Application.class)
@JoinTable(name="USER_APPLICATION_ROLE",
    joinColumns=@JoinColumn(name="USER_ID"),
    inverseJoinColumns=@JoinColumn(name="APPLICATION_ID"))
private Collection<Application> applications;

角色.java

@ManyToMany(mappedBy="roles", targetEntity=User.class)
private Collection<User> users = new ArrayList<User>();

应用程序.java

@ManyToMany(mappedBy="applications", targetEntity=User.class)
private Collection<User> users = new ArrayList<User>();

当我尝试运行以下测试时:

When I tried to run the following test:

    user.getRoles().add(role1);
    user.getRoles().add(role2);

    role1.getUsers().add(user);
    role1.getUsers().add(user);

    role2.getUsers().add(user);
    role2.getUsers().add(user);

    user.getApplications().add(app1);
    user.getApplications().add(app2);

    app1.getUsers().add(user);
    app2.getUsers().add(user);
      ......

      session.beginTransaction();
      session.save(user);
      session.save(role1);
      session.save(role2);
      session.save(app1);
      session.save(app2);

我收到以下错误:

Hibernate: select seq_cm_user.nextval from dual
Hibernate: select seq_role.nextval from dual
Hibernate: select seq_role.nextval from dual
Hibernate: select seq_application.nextval from dual
Hibernate: select seq_application.nextval from dual
Hibernate: insert into CM_USER (EMAIL, FIRST_NAME, LAST_NAME, MIDDLE_NAME, USERNAME, ID) values (?, ?, ?, ?, ?, ?)
Hibernate: insert into CM_ROLE (DESCRIPTION, ID) values (?, ?)
Hibernate: insert into CM_ROLE (DESCRIPTION, ID) values (?, ?)
Hibernate: insert into CM_APPLICATION (CODE, DESCRIPTION, ID) values (?, ?, ?)
Hibernate: insert into CM_APPLICATION (CODE, DESCRIPTION, ID) values (?, ?, ?)
Hibernate: insert into USER_APPLICATION_ROLE (USER_ID, APPLICATION_ID) values (?, ?)
Hibernate: insert into USER_APPLICATION_ROLE (USER_ID, APPLICATION_ID) values (?, ?)
Exception in thread "main" org.hibernate.exception.ConstraintViolationException: Could not execute JDBC batch update
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:96)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:275)
at org.hibernate.jdbc.AbstractBatcher.prepareStatement(AbstractBatcher.java:114)
at org.hibernate.jdbc.AbstractBatcher.prepareStatement(AbstractBatcher.java:109)
at org.hibernate.jdbc.AbstractBatcher.prepareBatchStatement(AbstractBatcher.java:244)
at org.hibernate.persister.collection.AbstractCollectionPersister.recreate(AbstractCollectionPersister.java:1179)
at org.hibernate.action.CollectionRecreateAction.execute(CollectionRecreateAction.java:58)
at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:273)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:265)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:188)
at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:321)
at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:51)
at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1216)
at org.hibernate.impl.SessionImpl.managedFlush(SessionImpl.java:383)
at org.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:133)
at com.hp.gdas.capman.HibernateTest.main(HibernateTest.java:73)

Caused by: java.sql.BatchUpdateException: ORA-01400: cannot insert NULL into ("SYSTEM"."USER_APPLICATION_ROLE"."ROLE_ID")
at oracle.jdbc.driver.DatabaseError.throwBatchUpdateException(DatabaseError.java:343)
at oracle.jdbc.driver.OraclePreparedStatement.executeBatch(OraclePreparedStatement.java:10657)
at org.hibernate.jdbc.BatchingBatcher.doExecuteBatch(BatchingBatcher.java:70)
at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:268)
... 14 more

非常感谢！

推荐答案

问题是您定义了与角色的关系和与应用程序的单独关系.没有声明任何特定用户是一个角色和一个应用程序的加入.

The problem is that you have defined a relationship to roles and a separate relationship to applications. There's no declaration that any specific user is a join of both one role and one application.

当您尝试与角色关联时，应用程序为空，反之亦然.

When you try to associate with a role, the application is null and visa-versa.

以下是使用 JPA 在 A、B 和 C 类之间映射三向连接的示例.注意，连接表不需要实体.

Here's an example of mapping a 3-way join between classes A, B and C using JPA. Note, no entity is required for the join table.

@Entity
public class A {

    @JoinTable(name = "a_b_c",
        joinColumns = @JoinColumn(name = "a_id"),
        inverseJoinColumns = @JoinColumn(name = "c_id"))
    @MapKeyJoinColumn(name = "b_id")
    @ElementCollection
    private Map<B, C> cByB = new HashMap<>();

}

@Entity
public class B {
    ...
}

@Entity
public class C {
    ...
}

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