JPA/Hibernate 嵌入式 ID

Question

JPA/Hibernate 嵌入式 ID

6

我想做这样的事情：

一个ReportingFile对象，可以是LogRequest或LogReport文件（两者结构相同）。
一个包含一个logRequest和一个日期列表的logReport列表的Reporting对象。

我尝试设置一个嵌入式ID，它将成为logRequest的属性。这就是我遇到的问题。我无法处理嵌入式ID。（http://docs.jboss.org/hibernate/stable/annotations/reference/en/html_single/#entity-mapping-identifier）

如果您有关于如何解决此问题的线索：）

以下是一个示例（不起作用）：

@Entity
@AssociationOverride( name="logRequest.fileName", joinColumns = { @JoinColumn(name="log_request_file_name") } )
public class Reporting {

    @EmbeddedId
    private ReportingFile logRequest;

    @CollectionOfElements(fetch = FetchType.EAGER)
    @JoinTable(name = "t_reports", schema="", joinColumns = {@JoinColumn(name = "log_report")})
    @Fetch(FetchMode.SELECT)
    private List<ReportingFile> reports;

    @Column(name="generated_date",nullable=true)
    private Date generatedDate;

    [...]
}

@Embeddable
public class ReportingFile {

    @Column(name="file_name",length=255)
    private String fileName;

    @Column(name="xml_content")
    private Clob xmlContent;

    [...]
}

在这个示例中，我遇到了以下错误：

    15.03.2010 16:37:59 [ERROR] org.springframework.web.context.ContextLoader       Context initialization failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor#0' defined in class path resource [config/persistenceContext.xml]: Initialization of bean failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [config/persistenceContext.xml]: Invocation of init method failed; nested exception is javax.persistence.PersistenceException: [PersistenceUnit: test] Unable to configure EntityManagerFactory
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:480)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory$1.run(AbstractAutowireCapableBeanFactory.java:409)
    at java.security.AccessController.doPrivileged(Native Method)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:380)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:264)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:221)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:261)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:185)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:164)
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:881)
    at org.springframework.context.support.AbstractApplicationContext.registerBeanPostProcessors(AbstractApplicationContext.java:597)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:366)
    at org.springframework.web.context.ContextLoader.createWebApplicationContext(ContextLoader.java:255)
    at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:199)
    at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:45)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:3843)
    at org.apache.catalina.core.StandardContext.start(StandardContext.java:4350)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
    at org.apache.catalina.core.StandardHost.start(StandardHost.java:719)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
    at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:443)
    at org.apache.catalina.core.StandardService.start(StandardService.java:516)
    at org.apache.catalina.core.StandardServer.start(StandardServer.java:710)
    at org.apache.catalina.startup.Catalina.start(Catalina.java:578)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:288)
    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:413)
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [config/persistenceContext.xml]: Invocation of init method failed; nested exception is javax.persistence.PersistenceException: [PersistenceUnit: test] Unable to configure EntityManagerFactory
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1337)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:473)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory$1.run(AbstractAutowireCapableBeanFactory.java:409)
    at java.security.AccessController.doPrivileged(Native Method)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:380)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:264)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:221)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:261)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:185)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:164)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeansOfType(DefaultListableBeanFactory.java:308)
    at org.springframework.beans.factory.BeanFactoryUtils.beansOfTypeIncludingAncestors(BeanFactoryUtils.java:270)
    at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.detectPersistenceExceptionTranslators(PersistenceExceptionTranslationInterceptor.java:122)
    at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.<init>(PersistenceExceptionTranslationInterceptor.java:78)
    at org.springframework.dao.annotation.PersistenceExceptionTranslationAdvisor.<init>(PersistenceExceptionTranslationAdvisor.java:70)
    at org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor.setBeanFactory(PersistenceExceptionTranslationPostProcessor.java:97)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1325)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:473)
    ... 29 more
Caused by: javax.persistence.PersistenceException: [PersistenceUnit: test] Unable to configure EntityManagerFactory
    at org.hibernate.ejb.Ejb3Configuration.configure(Ejb3Configuration.java:265)
    at org.hibernate.ejb.HibernatePersistence.createEntityManagerFactory(HibernatePersistence.java:125)
    at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:83)
    at org.springframework.orm.jpa.LocalEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalEntityManagerFactoryBean.java:91)
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:291)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1368)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1334)
    ... 46 more
Caused by: org.hibernate.AnnotationException: A Foreign key refering Reporting from Reporting has the wrong number of column. should be 2
    at org.hibernate.cfg.annotations.TableBinder.bindFk(TableBinder.java:272)
    at org.hibernate.cfg.annotations.CollectionBinder.bindCollectionSecondPass(CollectionBinder.java:1319)
    at org.hibernate.cfg.annotations.CollectionBinder.bindManyToManySecondPass(CollectionBinder.java:1158)
    at org.hibernate.cfg.annotations.CollectionBinder.bindStarToManySecondPass(CollectionBinder.java:600)
    at org.hibernate.cfg.annotations.CollectionBinder$1.secondPass(CollectionBinder.java:541)
    at org.hibernate.cfg.CollectionSecondPass.doSecondPass(CollectionSecondPass.java:43)
    at org.hibernate.cfg.Configuration.secondPassCompile(Configuration.java:1140)
    at org.hibernate.cfg.AnnotationConfiguration.secondPassCompile(AnnotationConfiguration.java:319)
    at org.hibernate.cfg.Configuration.buildMappings(Configuration.java:1125)
    at org.hibernate.ejb.Ejb3Configuration.buildMappings(Ejb3Configuration.java:1226)
    at org.hibernate.ejb.EventListenerConfigurator.configure(EventListenerConfigurator.java:159)
    at org.hibernate.ejb.Ejb3Configuration.configure(Ejb3Configuration.java:854)
    at org.hibernate.ejb.Ejb3Configuration.configure(Ejb3Configuration.java:191)
    at org.hibernate.ejb.Ejb3Configuration.configure(Ejb3Configuration.java:253)
    ... 52 more

- RoD

1个回答

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- Arthur Ronald · Accepted Answer

好的，让我们看一下

您有一个@AssociationOverride注释，其API说：

此注释用于重写实体关系的属性或字段的多对一或一对一映射。

并且

它可以应用于扩展映射超类的实体，以覆盖由映射超类定义的多对一或一对一映射

我在您的问题中没有看到@ManyToOne或@OnoToOne。因此，您的问题有些问题。

但是我在您的StackTrace中看到了以下日志

从Reporting引用Reporting的外键列数错误。应该是2

您的复合主键由@EmbeddedId注释定义，具有两个属性（fileName和xmlContent）

现在，让我们看看您的@CollectionOfElements

@CollectionOfElements(fetch=FetchType.EAGER)
@JoinTable(name="t_reports", 
    // Your mistake goes here
    joinColumns=@JoinColumn(name="log_report"))
@Fetch(FetchMode.SELECT)
private List<ReportingFile> reports;

它的外键只包含一个属性，而你的复合主键包含两个属性。 两者必须匹配。这就解释了为什么你看到这条好消息

从Reporting引用Reporting的外键列数不正确，应该是2

你正确的映射应该像这样

@CollectionOfElements(fetch=FetchType.EAGER)
@JoinTable(name="t_reports", 
    joinColumns={
        // The number of columns defined by our Compound primary key (2)
        // must match the number of columns defined by its Foreign key (2)
        @JoinColumn(name="file_name", referencedColumnName="file_name"),
        @JoinColumn(name="xml_content", referencedColumnName="xml_content")})
@Fetch(FetchMode.SELECT)
private List<ReportingFile> reports;

更多内容：我不知道您的目标数据库是否支持Clob作为主键。所以请记住这一点。

根据您的回复添加到原始答案中

1º 第一个场景（不使用 @CollectionOfElements）

@Entity
public class Reporting {

    // You said you just want a single fileName as primary key
    @Id
    @Column(name="file_name", nullable=false)
    private String fileName;

    // You said you still want to have the whole ReportingFile object
    @Embedded
    private ReportingFile reportingFile;

    @Embeddable
    public static class ReportingFile implements Serializable {

        // You must set up insertable=false, updatable=false
        @Column(name="file_name", insertable=false, updatable=false)
        private String fileName;

        @Column(name="xml_content")
        private Clob xmlContent;

   }

}

请记住以下内容：Hibernate不允许定义两个属性共享同一列。因此，我必须在 fileName 属性中定义 insertable=false, updatable=false。

当我执行以下操作时：

Reporting reporting = new Reporting();
reporting.setFileName("home.pdf");

ReportingFile reportingFile = new ReportingFile();
// It will not persisted because of insertable=false, updatable=false
reportingFile.setFileName("home.pdf");
reportingFile.setXmlContent(someClobObject);

session.save(reporting); // It works

第二步 第一个场景（使用 @CollectionOfElements）

@Entity
public class Reporting {

    // You said you just want a single fileName as primary key
    @Id
    @Column(name="file_name", nullable=false)
    private String fileName;

    // You said you still want to have the whole ReportingFile object
    @Embedded
    private ReportingFile reportingFile;

    @CollectionOfElements(fetch=FetchType.EAGER)
    @JoinTable(
        name="t_reports",
        joinColumns=@JoinColumn(name="file_name", referencedColumnName="file_name", insertable=false, updatable=false))
    private List<ReportingFile> reports;

    @Embeddable
    public static class ReportingFile implements Serializable {

        // You must set up insertable=false, updatable=false
        @Column(name="file_name", insertable=false, updatable=false)
        private String fileName;

        @Column(name="xml_content")
        private Clob xmlContent;

   }

}

当我执行以下操作时

Reporting reporting = new Reporting();
reporting.setFileName("home.pdf");

ReportingFile reportingFile = new ReportingFile();
// It will not persisted because of insertable=false, updatable=false
reportingFile.setFileName("home.pdf");
reportingFile.setXmlContent(someClobObject);

reporting.getReports().add(reportingFile);

session.save(reporting); // It does not work

Hibernate会抱怨

映射集合中的重复列：报告列：file_name

因此，当您有一个共享外键的@CollectionOfElements时，它将无法按预期工作。但是您可以采用解决方法。

@Entity
public class Reporting {

    // You said you just want a single fileName as primary key
    @Id
    @Column(name="file_name", nullable=false)
    private String fileName;

    // You said you still want to have the whole ReportingFile object
    @Embedded
    private ReportingFile reportingFile;

    // Your workaround goes here
    @CollectionOfElements(fetch=FetchType.EAGER)
    @JoinTable(
        name="t_reports",
        joinColumns=@JoinColumn(name="file_name", referencedColumnName="file_name"))
    private List<Clob> xmlContents;

    @Transient
    public List<ReportingFile> getReports() {
        List<ReportingFile> reports = new ArrayList<ReportingFile>();

        for(Clob xmlContent: getXmlContents())
            reports.add(new ReportingFile(getFileName(), xmlContent));

        return reports;
    }

    @Embeddable
    public static class ReportingFile implements Serializable {

        // required no-arg  constructor
        public ReportingFile() {}

        public ReportingFile(String fileName, Clob xmlContent) {
            this.fileName = fileName;
            this.xmlContent = xmlContent;
        }

        // You must set up insertable=false, updatable=false
        @Column(name="file_name", insertable=false, updatable=false)
        private String fileName;

        @Column(name="xml_content")
        private Clob xmlContent;

   }

}

请注意，当在拥有类内使用时，您可以将@Embeddable类定义为静态。