problem with inheriting foreign key property

czarek_r · **Posted:** Wed Jan 21, 2009 6:44 am

I've got a problem with inheriting a foreign key. I've got three classes:

Code:

@Entity
@Inheritance(strategy=InheritanceType.SINGLE_TABLE)
class Disc{
  @Id @GeneratedValue
  long id;
  @ManyToOne
  DiscCollection coll;
}

@Entity
class AudioDisc extends Disc{}

@Entity
class DiscCollection{
 @Id @GeneratedValue
  long id;
  @OneToMany(mappedBy="coll")
  List<Disc> discs = new ArrayList<Disc>();
}

Everything is OK here. However, if I change List generic type in the last class to:

Code:

List<AudioDisc> discs = new ArrayList<AudioDisc>();

then i get the following exception:

Code:

Caused by: org.hibernate.AnnotationException: mappedBy reference an unknown target entity property: tests.AudioDisc.coll in tests.DiscCollection.discs
   at org.hibernate.cfg.annotations.CollectionBinder.bindStarToManySecondPass(CollectionBinder.java:552)
   at org.hibernate.cfg.annotations.CollectionBinder$1.secondPass(CollectionBinder.java:517)
   at org.hibernate.cfg.CollectionSecondPass.doSecondPass(CollectionSecondPass.java:43)
   at org.hibernate.cfg.Configuration.secondPassCompile(Configuration.java:1130)
   at org.hibernate.cfg.AnnotationConfiguration.secondPassCompile(AnnotationConfiguration.java:316)
   at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1286)
   at org.hibernate.cfg.AnnotationConfiguration.buildSessionFactory(AnnotationConfiguration.java:915)

It looks like hibernate can't see that AudioDisc class inherits coll property from its Disc superclass. I can't find such example or any solution in the Manning book.

Regards,
czarek_r

mmerder · **Posted:** Wed Jan 21, 2009 8:31 am

Your mapping is kind of inconsistent if you change your type. Any Disc can belong to a DiscCollection, but a DiscCollection only consists of AudioDiscs? Thats not logical, so hibernate does not support it.

It's like defining a vehicle which can be parked in a building, but also saying that this building can only contain bicycles (which are vehicles).