Abstract Properties with a foreign key in Entity Framework 4.1? - entity-framework

Question

UPDATE:
I updated the classes to look more like my actual model. When I remove the Assignable property from the Document base entity, everything works.
Is something like this possible to map in EF 4.1?
public abstract class Entity
{
public Guid Id {get;set;}
}
public abstract class Assignable:Entity
{
}
public class Contact: Assignable
{
public string Name {get;set;}
}
public class Partner: Assignable
{
public string Area {get;set;}
}
public abstract class Document: Entity {
public Guid AssignedToId {get;set}
public Assignable AssignedTo {get;set;
}
public class Submittal: Document
{
public string SomeProperty {get;set;}
}
Mapping:
public class EntityConfiguration<TEntity> : EntityTypeConfiguration<TEntity>
where TEntity : Entity
{
protected EntityConfiguration()
{
HasKey(e => e.Id);
Property(e => e.Id).HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);
}
}
public class AssignableEntityMapping<TEntity>: EntityConfiguration<TEntity> where TEntity: Assignable
{
}
public class DocumentEntityMapping<TEntity>: EntityConfiguration<TEntity>
{
public DocumentEntityMapping()
{
HasOptional(e => e.AssignedTo).WithMany().HasForeignKey(e => e.AssignedToId);
}
}
public class ContactMapping: AssignableEntityMapping<Contact>
{
....
}
public class PartnerMapping: AssignableEntityMapping<Partner>
{
....
}
public class SubmittalMapping: DocumentEntityMapping<Submittal>
{
....
}
If this is possible how do I setup the mapping so that the AssignedToId is a foreign key to one of the concrete entities? I created a mapping for the Document entity and I get the error: "The property 'Id' is not a declared property on type..." I am guessing it is because EF doesn't know how to discriminate what the AssignedToId refers to?

Answer 1

I had a lot of extra architecture around the Contact and Partner entities that I could not use something like a TPH (Table Per Hierarchy) approach. EF doesn't know how to map the AssignedToId in the Document class since i was trying to use Table per Concrete Type (TPC) at the same time. I ended up just adding all the "assignable" types to the Document class for now. If there is another way around this, I'd like to know.
public abstract class Document: Entity
{
public Guid? AssignedContactId {get;set;}
public Contact AssignedContact {get;set;}
public Guid? AssignedPartnerId {get;set;}
public Partner AssignedPartner {get;set;}
}