Question

I have “table inheritance” in my DB (where descendants reference base with foreign key) and use Linq To Sql as my DAL:

[Table]
class Document {
    [Column]public int ID { get; set; }
    [Column]public int DocTypeID { get; set; }
    [Association]public Application Application { get; set; }
}

[Table]
class Application {
    [Column]public int ID { get; set; }
    [Column]public string AppType { get; set; }
    [Association]public Document Document {get;set}
}

Since L2S does not support multi-table inheritance Application is not inherited from Document. However, in my entity classes i do want inheritance:

class DocumentBase {
    public int ID { get; set; }
    public int DocTypeID { get; set; }
}

class MyApplication : DocumentBase {
    public string AppType { get; set; }
}

Now i’m creating the mappings:

Mapper.CreateMap<Document, DocumentBase>();
Mapper.CreateMap<Application, MyApplication>();

But AutoMapper complains about base properties in MyApplication not mapped. I don’t want to duplicate base properties in MyApplication map (too many descendants from DocumentBase). I found few posts suggesting custom ITypeConverter but don’t understand how to apply it to my scenario. What do i do?

Answer 1

Found this solution which also suffers from AssertConfigurationIsValid() complaining about base properties not mapped but slightly modified it:

static void InheritMappingFromBaseType<S, D>(this IMappingExpression<S, D> mappingExpression)
    where S: Document
    where D: DocumentBase
{
    mappingExpression // add any other props of Document
        .ForMember(d => d.DocTypeId, opt => opt.MapFrom(s => s.Document.DocTypeId);
}

Now it can be chained to each DocumentBase descendant map:

Mapper.CreateMap<Application, MyApplication>()
    .InheritMappingFromBaseType();

and AssertConfigurationIsValid() is happy.