[jboss-user] [JBoss Cache] New message: "Inconsistent behaviour when fetching cached subclass entities?"

[Jimmy Borg]

User development,

A new message was posted in the thread "Inconsistent behaviour when fetching cached subclass entities?":

http://community.jboss.org/message/527588#527588

Author  : Jimmy Borg
Profile : http://community.jboss.org/people/jborg

Message:
--------------------------------------------------------------
Hi all,
 
The use of jboss-cache as hibernate second-level cache is leading to inconsistent behaviour when fetching cached subclass entities as opposed to fetching non-cached subclass entities.
 
*Scenario*
Consider a simple scenario having a parent entity:
> @Entity
> @Table(name = "tt_test")
> @Inheritance(strategy = InheritanceType.SINGLE_TABLE)
> public abstract class ParentEntity implements Serializable {
>     
>     private static final long serialVersionUID = 5751958972675892020L;
>     
>     @Id
>     private String id;
>     
>     protected ParentEntity() {
>         super();
>     }
>     
>     public ParentEntity(String id) {
>         this.id = id;
>     }
>     
>     public String getId() {
>     
>         return id;
>     }
>     
> }
 
and two subclass entities extending the above entity:
> @Entity
> public final class Subclass1 extends ParentEntity {
> 
>     private static final long serialVersionUID = -4329753920470094896L;
> 
>     protected Subclass1() {
>         super();
>     }
>     
>     public Subclass1(String id) {
>         super(id);
>     }
> 
>     @Override
>     public String toString() {
> 
>         return "Subclass1 [ID={" + getId() + "}, Class={" + getClass() + "}]";
>     }
> }
 
> @Entity
> public final class Subclass2 extends ParentEntity {
> 
>     private static final long serialVersionUID = -6102575763486357670L;
> 
>     /**
>      * Default constructor (required for hibernation reasons)
>      */
>     protected Subclass2() {
>         super();
>     }
>     
>     public Subclass2(String id) {
>         super(id);
>     }
>     
> 
>     @Override
>     public String toString() {
> 
>         return "Subclass2 [ID={" + getId() + "}, Class={" + getClass() + "}]";
>     }
> }
 
After persisting an instance of Subclass1 using:
> em.persist(new Subclass1("identifier1")); 
 
Trying to fetch an instance of Subclass2 using:
> em.find(Subclass2.class, "identifier1");
 
will result in a +null+ return if the entity is not cached. This is the expected, correct behaviour.
 
However, when the entity with id +identifier1+ is cached, this will match and return an instance (of Subclass1) if the entity is cached. This appears to be both inconsistent behaviour, and a wrong result, as the entity with identifier +identifier1+ is of type Subclass1 not SubClass2, as requested in the call to em.find().
 
*Environment* 
jboss-cache 1.4.1.SP13
hibernate 3.2.5
jboss 4.2.2

--------------------------------------------------------------

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