Fluent NHibernate trying to map subclass of subclass using table-per-subclass - nhibernate

Question

I am building an application with heavy inheritance and have a part where there exists classes, A, B and C with:
class A
class B : A
class C : B
I implemented subclass mapping as a table-per-subclass style for class B as follows:
class BMap : SubclassMap<B>
{
public BMap()
{
Extends<A>();
KeyColumn("ID");
}
}
Which works perfectly. However, when I want to implement C as follows:
class CMap : SubclassMap<C>
{
public CMap()
{
Extends<B>();
KeyColumn("ID");
}
}
It results in the error
Duplicate class/entity mapping
I browsed the Hibernate/NHibernate forum but could not find an answer to this problem.

Answer 1

this does work as expected with NH 3.3.1.4000
public class A
{
public virtual int Id { get; protected set; }
}
public class B : A { }
public class C : B { }
public class AMap : ClassMap<A>
{
public AMap()
{
Id(x => x.Id);
}
}
public class BMap : SubclassMap<B> { }
public class CMap : SubclassMap<C> { }
public static void Main(string[] args)
{
var config = Fluently.Configure()
.Database(SQLiteConfiguration.Standard.InMemory().ShowSql().FormatSql())
.Mappings(m => m.FluentMappings
.Add<AMap>()
.Add<BMap>()
.Add<CMap>()
)
.BuildConfiguration();
using (var sf = config.BuildSessionFactory())
using (var session = sf.OpenSession())
{
new SchemaExport(config).Execute(true, true, false, session.Connection, null);
session.Save(new C());
session.Flush();
}
}