EJB3.0 Beta1 problems with query over inheritance

elmosca · **Joined:** Mon Mar 14, 2005 4:16 pm **Posts:** 27

Hi all, I am using the brand new EJB3.0 Beta1, but I am having a problem with an issue that did not happen using the Preview5.
I have implemented a single-table per class strategy (entities that extend a superclass, all mapped to the same table and using a discriminator). I have everything as the documentation tells:

For the superclass:

Code:

@Entity
@Table(name = "message_event")
@Inheritance(strategy = SINGLE_TABLE, discriminatorType = CHAR, discriminatorValue = "-")
@DiscriminatorColumn(name = "event_type")
@SequenceGenerator(name="seq_event", sequenceName="seq_event")
public class Event implements Serializable {
...
}

and, for instance, a subclass:

Code:

@Entity
@Inheritance(discriminatorValue="I")
public class InfoEvent extends Event{
...
}

If I create a query or a criteria looking for all entities 'from PersEvent' I get this exception:

Quote:

org.hibernate.WrongClassException: Object with id: 2 was not of the specified subclass: com.test.PersEvent

The object with id 2 isa InfoEvent (that extends Event), so no exception should be thrown. I did not happend using the Preview 5,

Has anybody else observed this behaviour? Am I missing something?

Regards,

Bruno

elmosca · **Joined:** Mon Mar 14, 2005 4:16 pm **Posts:** 27

Found the reason of this issue and I think it is a bug. If you use the @Column metadata for the attribute id, the polymorphic query files, but if you don't put the @Column (id column is created by default) everything works as expected...

Regards,

Bruno

emmanuel · **Posted:** Fri Jul 01, 2005 9:52 am

Can you post a runnable test case to JIRA please, I'll look at it.

Kango · **Joined:** Sun Jun 13, 2004 9:49 pm **Posts:** 38

Some more info on this.

I'm using the same thing and have found that when i run the query and have a look at the generated SQL, the discriminator ciolumn is missing.

This causes hibernate to give the above exception as it cannot determine the class type.

I'll remove the @Column annotation from the id and see what diff that makes.

Kango · **Joined:** Sun Jun 13, 2004 9:49 pm **Posts:** 38

Yep sure enough, i removed the @Column tag from the @Id property in the superclass and now my testcase works.

The query runs fine and the discriminator column is now present at the end of the column list.

So, this must be a bug.

Kango · **Joined:** Sun Jun 13, 2004 9:49 pm **Posts:** 38

It's not the @Column tag itself, but the name attribute. The existence of the annotation is ok, but if you rename the id column then the discriminator vanishes.

Shall i raise this as a bug?

emmanuel · **Posted:** Tue Jul 19, 2005 12:44 pm

post a runnable test case and I'll look at it

mentiro · **Joined:** Wed Mar 03, 2004 11:22 am **Posts:** 12

I have experienced this same problem - has a JIRA issue been created for it?

emmanuel · **Posted:** Sun Nov 06, 2005 9:39 am

This bug is solved in Hibernate3 core HEAD