在组合键上使用“链接”外键的问题

Posted 2023-01-21

我有一些OneToOne和ManyToOne关系，我想对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，父母和子女。祖父母与父母之间是一对一的关系，而子女与父母之间是一对多的关系，其中孩子具有由相关父母作为成员的复合键。

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;

父母：

@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;

儿童：

@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
    ...

此部署失败，但有以下例外：

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 [e-mail]//org.jboss.as.jpa.service.PersistenceUnitServiceImpl$1$1.run(PersistenceUnitServiceImpl.java:198)
    at [e-mail]//org.jboss.as.jpa.service.PersistenceUnitServiceImpl$1$1.run(PersistenceUnitServiceImpl.java:128)
    at [e-mail]//org.wildfly.security.manager.WildFlySecurityManager.doChecked(WildFlySecurityManager.java:649)
    at [e-mail]//org.jboss.as.jpa.service.PersistenceUnitServiceImpl$1.run(PersistenceUnitServiceImpl.java:212)
    at [e-mail]//org.jboss.threads.ContextClassLoaderSavingRunnable.run(ContextClassLoaderSavingRunnable.java:35)
    at [e-mail]//org.jboss.threads.EnhancedQueueExecutor.safeRun(EnhancedQueueExecutor.java:1982)
    at [e-mail]//org.jboss.threads.EnhancedQueueExecutor$ThreadBody.doRunTask(EnhancedQueueExecutor.java:1486)
    at [e-mail]//org.jboss.threads.EnhancedQueueExecutor$ThreadBody.run(EnhancedQueueExecutor.java:1377)
    at java.base/java.lang.Thread.run(Thread.java:835)
    at [e-mail]//org.jboss.threads.JBossThread.run(JBossThread.java:485)
Caused by: java.util.NoSuchElementException
    at java.base/java.util.ArrayList$Itr.next(ArrayList.java:999)
    at [e-mail]//org.hibernate.internal.util.collections.JoinedIterator.next(JoinedIterator.java:47)
    at [e-mail]//org.hibernate.cfg.annotations.TableBinder.linkJoinColumnWithValueOverridingNameIfImplicit(TableBinder.java:724)
    at [e-mail]//org.hibernate.cfg.PkDrivenByDefaultMapsIdSecondPass.doSecondPass(PkDrivenByDefaultMapsIdSecondPass.java:37)
    at [e-mail]//org.hibernate.boot.internal.InFlightMetadataCollectorImpl.processSecondPasses(InFlightMetadataCollectorImpl.java:1696)
    at [e-mail]//org.hibernate.boot.internal.InFlightMetadataCollectorImpl.processSecondPasses(InFlightMetadataCollectorImpl.java:1653)
    at [e-mail]//org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:287)
    at [e-mail]//org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.metadata(EntityManagerFactoryBuilderImpl.java:904)
    at [e-mail]//org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:935)
    at [e-mail]//org.jboss.as.jpa.hibernate5.TwoPhaseBootstrapImpl.build(TwoPhaseBootstrapImpl.java:44)
    at [e-mail]//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“父”字段的类型从“祖父母”更改为“父”，则部署失败，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，则它将成功部署，但是持久保存实体会产生IllegalArgumentException: Can not set java.lang.String field entity.ChildId.parent to entity.Parent。

我也试图从Child中删除JoinColumn批注，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，但是为了简单起见，我宁愿只使用@Ids。

答案

您可以尝试像这样映射Parent和Child，使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
    ...