Inheritence of Embedded objects (@Embeddable)

jpebe · **Joined:** Wed Oct 18, 2006 6:34 pm **Posts:** 4

Hi there @Hibernate (must be a pretty often repeated joke in here...)

I have an @Embeddable object AllocationId which extends another @Embeddable
object (GenericId). AllocationId, is simply a marker class and has NO attributes in it,
while all attributes (String id; which I want to persist) are in GenericId (inherited in AllocationId).

I get the following exception:

Code:

org.hibernate.AnnotationException: com.xxx.yyy.AllocationId has no persistent id property
        at org.hibernate.cfg.AnnotationBinder.bindId(AnnotationBinder.java:1714)
        at org.hibernate.cfg.AnnotationBinder.processElementAnnotations(AnnotationBinder.java:1171)
        at org.hibernate.cfg.AnnotationBinder.bindClass(AnnotationBinder.java:706)
        at org.hibernate.cfg.AnnotationConfiguration.processArtifactsOfType(AnnotationConfiguration.java:452)
        at org.hibernate.cfg.AnnotationConfiguration.secondPassCompile(AnnotationConfiguration.java:268)
        at org.hibernate.cfg.Configuration.buildMappings(Configuration.java:1039)
        at org.hibernate.ejb.Ejb3Configuration.buildMappings(Ejb3Configuration.java:1207)
        at org.hibernate.ejb.EventListenerConfigurator.configure(EventListenerConfigurator.java:154)
        at org.hibernate.ejb.Ejb3Configuration.configure(Ejb3Configuration.java:844)
        at org.hibernate.ejb.Ejb3Configuration.configure(Ejb3Configuration.java:382)
        at org.hibernate.ejb.HibernatePersistence.createContainerEntityManagerFactory(HibernatePersistence.java:126)
        at org.jboss.ejb3.entity.PersistenceUnitDeployment.start(PersistenceUnitDeployment.java:264)
        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:585)
        at org.jboss.ejb3.ServiceDelegateWrapper.startService(ServiceDelegateWrapper.java:102)
        at org.jboss.system.ServiceMBeanSupport.jbossInternalStart(ServiceMBeanSupport.java:289)
        at org.jboss.system.ServiceMBeanSupport.jbossInternalLifecycle(ServiceMBeanSupport.java:245)
        at sun.reflect.GeneratedMethodAccessor144.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)

Any Ideas ?

Code snippets as follow:

Code:

@Embeddable
public final class AllocationId extends GenericId {

   // ... serial UID here - removed as considered somewhat sensitive ...

    /**
     * @param id
     */
    public AllocationId(final String id) {
        super(id);
    }
}

Code:

@Embeddable
public abstract class GenericId implements Serializable {

    /**
     * The actual Id
     */
    protected String id; // THIS IS NOT BEING 'SEEN' AS INSIDE AllocationId

    /**
     * Constructor to create a generic Id.
     * Syntactic checks are performed here (not null and empty string)
     *
     * @param allocationId The allocation Id
     */
    protected GenericId(final String id) {
        validate(id);
        this.id = id;
    }

    /**
     * Performs syntactic checking of the generic id
     *
     * @param id may not be null or empty ""
     */
    private void validate(final String id) throws IllegalArgumentException {

        if (id == null) {
            throw new IllegalArgumentException("id cannot be null");
        }
        if (id.trim().length() == 0) {
            throw new IllegalArgumentException("id cannot be length 0");
        }
    }

    /**
     * @return the id
     */
    public String getId() {
        return this.id;
    }

    @Override
    public String toString() {
        return getId();
    }

    // some less interesting code here .equals overrides etc.
}

Let me know.

Many Thanks - for your attention and for your GREAT product,
Malta (MT).

jpebe · **Joined:** Wed Oct 18, 2006 6:34 pm **Posts:** 4

My dear self,

This wasn't that hard after all:

Code:

@MappedSuperclass
public abstract class GenericId implements Serializable {
   // rest of the broth...

}

You need to explicitly use the hibernate specific @MappedSuperclass - otherwise all super classes will be ignored.

Also note that this is not official EJB3 spec, but rather Hibernate extensions - so you are marrying Hibernate (which isn't too bad I guess)

emmanuel · **Posted:** Thu Oct 19, 2006 8:04 pm

correct
Something that is not possible (read not tested nor supported) is to have a class both @Embeddable and @MappedSuperclass (ie inherited).
But I guess this kind of case is pretty uncommon

jpebe · **Joined:** Wed Oct 18, 2006 6:34 pm **Posts:** 4

Emmanuel,

do you see this as a shortcoming in the EJB3 spec ?

how come something as @MappedSuperclass didn't make it to the spec ? I would think that Id (and embeddable object) inheritence would be pretty much the common case rather than the exception.

cheers
JP

emmanuel · **Posted:** Wed Oct 25, 2006 11:38 am

no
@MappedSuperclass *is* in the spec and is usable for @Entity superclasses
@MappedSuperclass usable for @Embeddable superclasses is an hibernate extension (sowewhat useful I thing)
@MappedSuperclass and @Entity on the same class or @MappedSuperclass and @Embeddable on the same class or @Entity and @Embeddable on the same class are not supported by the spec nor Hibernate Annotations

jpebe · **Joined:** Wed Oct 18, 2006 6:34 pm **Posts:** 4

Looks like all of a sudden (4 years down the line) this is supported (both @MappedSuperclass and @Embeddable) because we were having problems (attribute was null in the database) and when we marked the class with both annotations it worked.

Some development there.
JP