abstract entity and subclasses for components

[robshep]

Recently we had,

@Entity
@Name("user")
@Scope(SESSION)
public class User { ... }

But now we must change it to the following structure:

public abstract class User { ... }

public class UserTypeA extends User { ... }

public class UserTypeB extends User { ... }

However,

I've tried various combinations of the @Entity, @Name and @Scope annotations,

It seems I can't have multiple sub-types with @Name

Two components with the same name and precedence - component name: user

But if they exist on User SEAM complains that User is abstract.

Then, making User non-abstract (not ideal) I see it get's installed (But only the super-type)
The other types don't get a mention.

I see examples like this have been raised, but this is a simple case of polymorphism, where the concrete sub-types provide minor implementation differences.  The whole application (apart from a single other method) just requires:

@In User user

Any hints on what to do?

Thanks and kind regards

Rob

[sean.tozer]

Try the following mapping:

@MappedSuperClass
abstract class User { ... }

@Entity
@Table(..)
class UserA extends User { ... }

That will map UserA to the correc table, whatever it is in your setup, while still alowing both user types to be stored in a User variable. The trick of course is the MappedSuperClass, which makes Seam (through Hibernate) aware of the class and hierarchy without actually trying to map it to any instantiable entity.