在复合键上使用“链式”外键时出现问题

Question

我有几个 OneToOne 和 ManyToOne 关系，我想为每个元素使用相同的主键，将键从父级“链接”到子级。

我的模型 (MWE) 具有三个实体：祖父母、父母和孩子。 Grandparent 和 Parent 是一对一相关的，而 Child 和 Parent 是多对一相关的，Child 具有一个以相关 Parent 作为成员的复合键。

实现如下：

祖父母：

@Entity
@Table(name = "GRANDPARENT")
public class Grandparent implements Serializable {
    @Id
    @Column(length = 20)
    String grandparentId;

    @OneToOne(mappedBy = "grandparent", cascade = CascadeType.ALL)
    Parent parent;
}

家长：

@Entity
@Table(name = "PARENT")
public class Parent implements Serializable {
    @Id
    @OneToOne
    @JoinColumn(name = "grandparent")
    Grandparent grandparent;

    @OneToMany(mappedBy = "parent", cascade = CascadeType.ALL)
    List<Child> child;
}

孩子：

@Entity
@IdClass(ChildId.class)
@Table(name = "CHILD")
public class Child implements Serializable {
    @Id
    @ManyToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
    @JoinColumn(name = "parent", referencedColumnName = "grandparent", columnDefinition = "varchar(20)")
    Parent parent;

    @Id
    @Column(length = 20)
    String childStringId;
}

ChildId：

public class ChildId implements Serializable {  
    Grandparent parent; // should have the type of the Id of "parent", according to the JPA spec
    String childStringId;

    // hashCode and equals methods
    ...
}

部署失败，但出现以下异常：

14:03:52,579 ERROR [org.jboss.msc.service.fail] (ServerService Thread Pool -- 85) MSC000001: Failed to start service jboss.persistenceunit."hibernateMWE.war#pu": org.jboss.msc.service.StartException in service jboss.persistenceunit."hibernateMWE.war#pu": java.util.NoSuchElementException
    at org.jboss.as.jpa@17.0.1.Final//org.jboss.as.jpa.service.PersistenceUnitServiceImpl$1$1.run(PersistenceUnitServiceImpl.java:198)
    at org.jboss.as.jpa@17.0.1.Final//org.jboss.as.jpa.service.PersistenceUnitServiceImpl$1$1.run(PersistenceUnitServiceImpl.java:128)
    at org.wildfly.security.elytron-private@1.9.1.Final//org.wildfly.security.manager.WildFlySecurityManager.doChecked(WildFlySecurityManager.java:649)
    at org.jboss.as.jpa@17.0.1.Final//org.jboss.as.jpa.service.PersistenceUnitServiceImpl$1.run(PersistenceUnitServiceImpl.java:212)
    at org.jboss.threads@2.3.3.Final//org.jboss.threads.ContextClassLoaderSavingRunnable.run(ContextClassLoaderSavingRunnable.java:35)
    at org.jboss.threads@2.3.3.Final//org.jboss.threads.EnhancedQueueExecutor.safeRun(EnhancedQueueExecutor.java:1982)
    at org.jboss.threads@2.3.3.Final//org.jboss.threads.EnhancedQueueExecutor$ThreadBody.doRunTask(EnhancedQueueExecutor.java:1486)
    at org.jboss.threads@2.3.3.Final//org.jboss.threads.EnhancedQueueExecutor$ThreadBody.run(EnhancedQueueExecutor.java:1377)
    at java.base/java.lang.Thread.run(Thread.java:835)
    at org.jboss.threads@2.3.3.Final//org.jboss.threads.JBossThread.run(JBossThread.java:485)
Caused by: java.util.NoSuchElementException
    at java.base/java.util.ArrayList$Itr.next(ArrayList.java:999)
    at org.hibernate@5.3.10.Final//org.hibernate.internal.util.collections.JoinedIterator.next(JoinedIterator.java:47)
    at org.hibernate@5.3.10.Final//org.hibernate.cfg.annotations.TableBinder.linkJoinColumnWithValueOverridingNameIfImplicit(TableBinder.java:724)
    at org.hibernate@5.3.10.Final//org.hibernate.cfg.PkDrivenByDefaultMapsIdSecondPass.doSecondPass(PkDrivenByDefaultMapsIdSecondPass.java:37)
    at org.hibernate@5.3.10.Final//org.hibernate.boot.internal.InFlightMetadataCollectorImpl.processSecondPasses(InFlightMetadataCollectorImpl.java:1696)
    at org.hibernate@5.3.10.Final//org.hibernate.boot.internal.InFlightMetadataCollectorImpl.processSecondPasses(InFlightMetadataCollectorImpl.java:1653)
    at org.hibernate@5.3.10.Final//org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:287)
    at org.hibernate@5.3.10.Final//org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.metadata(EntityManagerFactoryBuilderImpl.java:904)
    at org.hibernate@5.3.10.Final//org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:935)
    at org.hibernate.jipijapa-hibernate5-3@17.0.1.Final//org.jboss.as.jpa.hibernate5.TwoPhaseBootstrapImpl.build(TwoPhaseBootstrapImpl.java:44)
    at org.jboss.as.jpa@17.0.1.Final//org.jboss.as.jpa.service.PersistenceUnitServiceImpl$1$1.run(PersistenceUnitServiceImpl.java:170)
    ... 9 more

14:03:52,580 ERROR [org.jboss.as.controller.management-operation] (DeploymentScanner-threads - 2) WFLYCTL0013: Operation ("full-replace-deployment") failed - address: ([]) - failure description: {"WFLYCTL0080: Failed services" => {"jboss.persistenceunit.\"hibernateMWE.war#pu\"" => "java.util.NoSuchElementException
    Caused by: java.util.NoSuchElementException"}}

如果我将 ChildId 中“parent”字段的类型从 Grandparent 更改为 Parent，则部署将失败并显示 MappingException: Unable to find column with logical name: grandparent in org.hibernate.mapping.Table(PARENT) and its related supertables and secondary tables。如果我改为将其更改为 String，它会成功部署，但持久化实体会引发 IllegalArgumentException: Can not set java.lang.String field entity.ChildId.parent to entity.Parent。

我也尝试从 Child 中删除 JoinColumn 注释，但这会导致以下异常：

 Caused by: org.hibernate.MappingException: Foreign key (FKdjmtwrjnm98ag78day8q0okub:CHILD [])) must have same number of columns as the referenced primary key (PARENT [grandparent])"}

我在 wildfly 17.0.1.Final 上使用 Hibernate 5.3.10.Final，我的数据库是 MariaDB 10.0.38。我已经使用@MapsId 进行了此映射，但为了简单起见，我宁愿只使用@Ids。

Answer 1

您可以尝试像这样映射Parent 和Child，让Grandparent 保持原样：

@Entity
@Table(name = "PARENT")
public class Parent implements Serializable {
    @Id
    String id;

    @OneToOne
    @JoinColumn(name = "grandparent")
    @MapsId
    Grandparent grandparent;

    @OneToMany(mappedBy = "parent", cascade = CascadeType.ALL)
    List<Child> child;
}

@Entity
@IdClass(ChildId.class)
@Table(name = "CHILD")
public class Child implements Serializable {
    @Id
    @ManyToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
    @JoinColumn(name = "parent", referencedColumnName = "grandparent", columnDefinition = "varchar(20)")
    Parent parent;

    @Id
    @Column(length = 20)
    String childStringId;
}

public class ChildId implements Serializable {  
    String parent; // should have the type of the Id of "parent", according to the JPA spec
    String childStringId;

    // hashCode and equals methods
    ...
}