Question

结合使用Hibernate和mysql。

当我尝试从联接表继承的子项创建@OneToOne关系时，同时也使用@MapsId映射联接表子项的ID。

为了测试它，我什至创建了一个具有以下结构的测试项目：

联合表父级

@Entity
@Table(name = "test_joined_bases")
@Getter
@Setter
@NoArgsConstructor
@Inheritance(strategy = InheritanceType.JOINED)
public class AJoinedBase implements Serializable {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
}

加入餐桌的孩子

@Entity
@Table(name = "test_joined_children")
@Getter
@Setter
@NoArgsConstructor
@PrimaryKeyJoinColumn(name = "id")
public class JoinedChild extends AJoinedBase {
    @OneToOne(mappedBy = "note", fetch = FetchType.LAZY, cascade = CascadeType.ALL, optional = false)
    private NoteContent content;
}

OneToOne扩展

@Entity
@Table(name = "test_joined_child_extensions")
@Getter
@Setter
@NoArgsConstructor
public class JoinedChildExtension implements Serializable {
    @Id
    private Long id;

    @OneToOne(fetch = FetchType.LAZY)
    @MapsId
    private JoinedChild joinedChild;
}

但是，我什至无法启动spring boot应用程序而不会引发错误。问题似乎是Hibernate无法找到所引用实体的键列（此处为JoinedChild），因此在调用columnIterator.next（）;时抛出NullPointerException。我相信发生这种情况的原因是，由于联接表继承，键被保存在wrappedValue中。
谁能帮我解决这个问题，或者这是Hibernate ORM的问题吗？

StackTrace

构建项目时，出现以下错误：

2018-08-10 18:54:20.611  WARN 9836 --- [           main] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaConfiguration.class]: Invocation of init method failed; nested exception is java.util.NoSuchElementException
[...]
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaConfiguration.class]: Invocation of init method failed; nested exception is java.util.NoSuchElementException
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1706) ~[spring-beans-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:579) ~[spring-beans-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:501) ~[spring-beans-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:317) ~[spring-beans-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228) ~[spring-beans-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:315) ~[spring-beans-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) ~[spring-beans-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1089) ~[spring-context-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:859) ~[spring-context-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:550) ~[spring-context-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:140) ~[spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:759) [spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:395) [spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:327) [spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1255) [spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1243) [spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE]
    at com.studynote.StudynoteBackendApplication.main(StudynoteBackendApplication.java:27) [classes/:na]
Caused by: java.util.NoSuchElementException: null
    at java.util.ArrayList$Itr.next(ArrayList.java:862) ~[na:1.8.0_171]
    at org.hibernate.cfg.annotations.TableBinder.linkJoinColumnWithValueOverridingNameIfImplicit(TableBinder.java:724) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.cfg.PkDrivenByDefaultMapsIdSecondPass.doSecondPass(PkDrivenByDefaultMapsIdSecondPass.java:37) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.processSecondPasses(InFlightMetadataCollectorImpl.java:1640) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.processSecondPasses(InFlightMetadataCollectorImpl.java:1597) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:278) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.metadata(EntityManagerFactoryBuilderImpl.java:861) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:888) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.springframework.orm.jpa.vendor.SpringHibernateJpaPersistenceProvider.createContainerEntityManagerFactory(SpringHibernateJpaPersistenceProvider.java:57) ~[spring-orm-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:365) ~[spring-orm-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:390) ~[spring-orm-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:377) ~[spring-orm-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.afterPropertiesSet(LocalContainerEntityManagerFactoryBean.java:341) ~[spring-orm-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1765) ~[spring-beans-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1702) ~[spring-beans-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    ... 16 common frames omitted

Answer 1

@MapId是为可嵌入ID设计的有关更多详细信息，您可以阅读here 我已经解决了我用@JoinColumn（“ nameOfColumn”）替换@MapId（“ nameOfColumn”）

的问题

Answer 2

@MapsId 非常适合与 @OneToOne 关系一起使用。有关用法，请参阅这些文章：

One-to-One Relationship in JPA。

The best way to map a @OneToOne relationship with JPA and Hibernate。

然而，NoSuchElementException 在堆栈跟踪中可能是因为将 @Inheritance(strategy = InheritanceType.JOINED) 与 @MapsId 一起使用。这些 Hibernate 问题单中描述了该问题： HHH-13335、HHH-13295 和 HHH-7135。

目前，所有三张票都未解决。我们必须等待这个错误被修复。同时，您可以使用 InheritanceType.SINGLE_TABLE 或 InheritanceType.TABLE_PER_CLASS 和 @MapsId 作为解决方法。有关这些 InheritanceType 替代方案的用法，请参阅 this article。

Hibernate通过OneToOne和@MapsId联合表继承IM

联合表父级

加入餐桌的孩子

OneToOne扩展

StackTrace

2 个答案: