如何在Hibernate 3.6的主键上正确地级联保存一对一的双向关系

Question

我与共享密钥具有一对一的双向实体关系。当我尝试保存关联的所有者时，对于该关系的拥有方，我收到一个“生成的null ID”异常。我正在使用hibernate-
entitymanager并使用spring进行事务管理。

所属实体

@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;
    }
}

所属实体

@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);

在hibernate3.5.0-最终版中，这一切都可以正常工作。尝试升级到3.5.6-Final或3.6.0.Final时，是我开始获取“为LeadAffiliate生成的空ID”的错误：

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，我不确定关于Lead Affiliate的注解是否正确。他们工作了，但似乎有些k昧。因此，我将其更改为：

@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。（仅适用于3.5.0，不适用于3.5.6或3.6.0）

我需要一种新的方式来执行此操作，还是这是一个错误？我担心的是我的代码由于//错误而正在运行。

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

当前一个实体（“从属”实体）是与该实体多对一或一对一关系的所有者时，一个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关系映射到父关系。

在您的情况下LeadAffiliate是派生的，因此应为所有者，何时Lead应由标记为非所有者mappedBy。以下在3.5.0和3.5.6中均适用：

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;

    ...
}