如何正确级联在Hibernate 3.6中保存主键上的一对一双向关系

Question

我与共享密钥有一对一的双向实体关系.当我尝试保存关联的所有者时,我得到了一个"null id generated"异常,对照关系的拥有方.我正在利用hibernate-entitymanager并使用spring进行事务管理.

拥有实体

@Entity
@Table(name = "lead")
public class Lead
{
    private Long leadId;

    private LeadAffiliate leadAffiliate;

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    public Long getLeadId()
    {
        return leadId;
    }

    @OneToOne(cascade = CascadeType.ALL)
    @PrimaryKeyJoinColumn
    public LeadAffiliate getLeadAffiliate()
    {
        return leadAffiliate;
    }
}

拥有实体

@Entity
@Table(name = "lead_affiliate")
public class LeadAffiliate
{
    private Long leadId;

    private Lead lead;

    @Id
    public Long getLeadId()
    {
        return leadId;
    }

    @MapsIdmappedBy = "leadAffiliate")
    @OneToOne(cascade = CascadeType.All)
    @PrimaryKeyJoinColumn
    @JoinColumn(name = "lead_id")
    public Lead getLead()
    {
        return lead;
    }
}

并且以下代码用于保存实体:

LeadAffiliate aff = new LeadAffiliate();

aff.setLead(lead);
lead.setLeadAffiliate(aff);

em.persist(lead);

这一切在hibernate 3.5.0-Final中完全正常.当尝试升级到3.5.6-Final或3.6.0.Final时,我开始得到"为LeadAffiliate生成的空id"错误:

javax.persistence.PersistenceException: org.hibernate.id.IdentifierGenerationException: null id generated for:class com.sellingsource.bizdev.entities.LeadAffiliate
    at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1214)
    at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1147)
    at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1153)
    at org.hibernate.ejb.AbstractEntityManagerImpl.persist(AbstractEntityManagerImpl.java:678)
    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.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerInvocationHandler.invoke(ExtendedEntityManagerCreator.java:365)
    at $Proxy152.persist(Unknown Source)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:240)
    at $Proxy120.persist(Unknown Source)
    at com.sellingsource.common.dao.JpaGenericDao.create(JpaGenericDao.java:38)
    ... 64 more
Caused by: org.hibernate.id.IdentifierGenerationException: null id generated for:class com.sellingsource.bizdev.entities.LeadAffiliate
    at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:123)
    at org.hibernate.ejb.event.EJB3PersistEventListener.saveWithGeneratedId(EJB3PersistEventListener.java:69)
    at org.hibernate.event.def.DefaultPersistEventListener.entityIsTransient(DefaultPersistEventListener.java:179)
    at org.hibernate.event.def.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:135)
    at org.hibernate.impl.SessionImpl.firePersist(SessionImpl.java:799)
    at org.hibernate.impl.SessionImpl.persist(SessionImpl.java:791)
    at org.hibernate.engine.EJB3CascadingAction$1.cascade(EJB3CascadingAction.java:48)
    at org.hibernate.engine.Cascade.cascadeToOne(Cascade.java:392)
    at org.hibernate.engine.Cascade.cascadeAssociation(Cascade.java:335)
    at org.hibernate.engine.Cascade.cascadeProperty(Cascade.java:204)
    at org.hibernate.engine.Cascade.cascade(Cascade.java:161)
    at org.hibernate.event.def.AbstractSaveEventListener.cascadeBeforeSave(AbstractSaveEventListener.java:450)
    at org.hibernate.event.def.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:282)
    at org.hibernate.event.def.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:203)
    at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:129)
    at org.hibernate.ejb.event.EJB3PersistEventListener.saveWithGeneratedId(EJB3PersistEventListener.java:69)
    at org.hibernate.event.def.DefaultPersistEventListener.entityIsTransient(DefaultPersistEventListener.java:179)
    at org.hibernate.event.def.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:135)
    at org.hibernate.event.def.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:61)
    at org.hibernate.impl.SessionImpl.firePersist(SessionImpl.java:808)
    at org.hibernate.impl.SessionImpl.persist(SessionImpl.java:782)
    at org.hibernate.impl.SessionImpl.persist(SessionImpl.java:786)
    at org.hibernate.ejb.AbstractEntityManagerImpl.persist(AbstractEntityManagerImpl.java:672)
    ... 77 more

顺便说一句,我不确定Lead Affiliate的注释是否适合开始.他们工作,但似乎有点kludgey.所以我后来改为:

@Entity
@Table(name = "lead_affiliate")
public class LeadAffiliate
{
    private Long leadId;

    private Lead lead;

    @Id
    @GenericGenerator(name = "foreign", strategy = "foreign", parameters = {
                    @org.hibernate.annotations.Parameter(name = "property", value="lead")
    })
    @GeneratedValue(generator = "foreign")
    public Long getLeadId()
    {
        return leadId;
    }

    @OneToOne(mappedBy = "leadAffiliate")
    @PrimaryKeyJoinColumn
    public Lead getLead()
    {
        return lead;
    }
}

但是,通过这些更改,我得到了相同的结果.(适用于3.5.0但不适用3.5.6或3.6.0)

有没有新方法我需要这样做或这是一个错误？我担心的是我的代码目前正在运行,因为有一个bug:/.

Answer 1

规范说派生实体应该是关系的拥有方:

2.4.1对应于派生身份的主键

当前实体("从属"实体)是多对一或一对一关系的所有者时,实体的身份可以从另一个实体("父"实体)的身份派生.父实体和外键将关系从依赖映射到父.

在你的情况下LeadAffiliate派生,所以它应该是所有者,何时Lead应该被标记为非拥有方mappedBy.以下适用于3.5.0和3.5.6:

public class Lead { 
    @Id @GeneratedValue
    private Long leadId; 

    @OneToOne(cascade = CascadeType.ALL, mappedBy = "lead")
    private LeadAffiliate leadAffiliate; 

    ...
}

.

public class LeadAffiliate {  
    @Id
    private Long leadId;  

    @OneToOne @MapsId
    private Lead lead; 

    ...
}

Answer 2

我的答案不能解释为什么事情正在使用Hibernate 3.5.0-Final,但不能使用3.5.6-Final或3.6.0.Final(你应该报告这个,我称之为回归).

无论如何,JPA 2.0中以标准方式更好地支持派生标识符,在您的情况下,我认为您可以简单地使用注释来注释您的OneToOne关系Id.

更新:如axtavt所示,当使用派生标识符时,"依赖"实体必须是关系的所有者.因此,依赖实体的完整映射将是:

@Entity
@Table(name = "lead_affiliate")
public class LeadAffiliate {
    private Lead lead;

    @Id
    @OneToOne
    @JoinColumn(name="FK")
    public Lead getLead() {
        return lead;
    }
}

而"父母"实体:

@Entity
@Table(name = "lead")
public class Lead {
    private Long leadId;

    private LeadAffiliate leadAffiliate;

    @Id @GeneratedValue(strategy = GenerationType.AUTO)
    public Long getLeadId() {
        return leadId;
    }

    @OneToOne(cascade = CascadeType.ALL, mappedBy="lead")
    public LeadAffiliate getLeadAffiliate() {
        return leadAffiliate;
    }
}

这是一个有效的JPA 2.0映射,可与EclipseLink一起使用.但是,Hibernate不喜欢它并且不会实例化EntityManagerFactory(该死!).

作为解决方法,您将必须使用axtavt建议的解决方案,即声明主键属性以及关系属性并在关系属性上使用MapsId.

但上面应该有效,有一个IMO在Hibernate中有一个错误(报告为HHH-5695).

参考

• JPA 2.0规范
  • 第2.4.1节"与派生身份相对应的主键"(冗长,涵盖许多情况)
• JPA Wikibook
  • 通过OneToOne关系的主键