Allow more flexible conditional mapping for TPH and similar

I have the following model

public class BaseType
    {
        public string Code {get;set;}
        public string Type {get;set;}
}
public class ChildType:BaseType
    {
        public ChildType()=> Type = "ExplicitChild"
        public string AdditionalData {get;set;}
}

I am able to create a BaseType with a type value as “Implicit Child” and save it to the database, but when retrieving the information I can not get a reference to the “Implicit Child.”

db.Set<BaseType>().ToList();

This is caused by the discriminator column being present in the where clause at all times.

Where [e].[Type] IN (N'ExplicitChild', N'BaseType')

I would expect one of the following

• Prevent saving of arbitrary discriminator.
• Don’t check the discriminator column at all when using the base set without any constraints. <== preferred for my case

Further technical details

EF Core version: 2.0.0 Database Provider: SqlLite, MSSql Operating system: Windows 10 IDE:Visual Studio 2017

[Tarig0]

on your point on what would I expect when creating a base type, I would expect the discriminator to have to be explicitly defined, before attaching the entity.

Another option is to add a fluent function to the hasdiscriminator path, something like “HasDefaultDiscriminator” or have hasvalue<T> have the overload that takes an ienumerable<t> require a T param to be passed for the default

typeEnum Type {get;set}

modelBuilder.Entity<BaseClass>().HasDiscriminator(e=>e.Type)
   .HasValue<ExplicitChild>(typeEnum.ExplicitChild)
   .HasValue<BaseClass>(typeEnum.Child1,typeEnum.Child2)
   .HasDefaultDiscriminator<BaseClass>(typeEnum.Child1);

modelBuilder.Entity<BaseClass>().HasDiscriminator(e=>e.Type)
   .HasValue<ExplicitChild>(typeEnum.ExplicitChild)
   .HasValue<BaseClass>(default:typeEnum.Child1, typeEnum.Child1,typeEnum.Child2)

[gojanpaolo]

Are there any workarounds to assign multiple discriminator values for a single derived type?