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;}
}