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

I have an one-to-one, bidirectional entity relationship with shared keys. When I attempt to save the owner of the association I get a "null id generated" exception against the owned side of the relationship. I am utilizing hibernate-entitymanager and using spring for transaction management.

Owning Entity

@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;
    }
}

Owned Entity

@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;
    }
}

and the code below is being used to save the entity:

LeadAffiliate aff = new LeadAffiliate();

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

em.persist(lead);

This all works perfectly fine in hibernate 3.5.0-Final. When attempting to upgrade to 3.5.6-Final or 3.6.0.Final is when I start getting the "null id generated for LeadAffiliate" error:

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

As an aside, I am not sure that the annotations on Lead Affiliate were quite right to begin with. They worked, but seemed kind of kludgey. So I have since changed them to:

@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;
    }
}

However, with these changes I get the same result. (Works in 3.5.0 but not 3.5.6 or 3.6.0)

Is there a new way I need to be doing this or is this a bug? My concern is that my code is currently working because of a bug :/.

Answer 1

Specification says that derived entity should be the owning side of the relationship:

The identity of an entity may be derived from the identity of another entity (the "parent" entity) when the former entity (the "dependent" entity) is the owner of a many-to-one or one-to-one relationship to the parent entity and a foreign key maps the relationship from dependent to parent.

In your case LeadAffiliate is derived, so it should be the owner, when Lead should be marked as non-owning side by mappedBy . The following works in both 3.5.0 and 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

My answer won't explain why things are working with Hibernate 3.5.0-Final but don't with 3.5.6-Final or 3.6.0.Final (and you should report this, I call this a regression).

Anyway, derived identifiers are much better supported in JPA 2.0, in a standard way, and in your case, I think you could simply annotate your OneToOne relation with an Id annotation.

Update: As underlined by axtavt, when using a derived identifier, the "dependent" entity must be the owner of the relationship. So the full mapping for the dependent entity would be:

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

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

And the "parent" entity:

@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;
    }
}

This is a valid JPA 2.0 mapping, and works with EclipseLink . However, Hibernate doesn't like it and won't instantiate the EntityManagerFactory (dammit!).

As workaround, you'll have to use the solution suggested by axtavt ie to declare a primary key attribute as well as the relationship attribute and to use MapsId on the relationship attribute.

But the above should work, there is IMO a bug in Hibernate (reported as HHH-5695 ).

References

• JPA 2.0 Specification
  • Section 2.4.1 "Primary Keys Corresponding to Derived Identities" (lengthy, covers many cases)
• JPA Wikibook
  • Primary Keys through OneToOne Relationships