Multiple column discriminator

[vslee]

Is there a way to use multiple columns as a discriminator? I tried putting those columns into an owned type, but EF Core did not like it. Here is my attempt:

using Microsoft.EntityFrameworkCore;
using System.ComponentModel.DataAnnotations.Schema;

namespace MultipleDiscriminatorColumns
{
	class Program
	{
		static void Main(string[] args) { }
	}
	public class BloggingContext : DbContext
	{
		public DbSet<BaseType> BaseTypeSet { get; set; }

		protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
		{
			optionsBuilder.UseSqlServer(
				@"Server=(localdb)\mssqllocaldb;Database=Blogging;Integrated Security=True");
		}

		protected override void OnModelCreating(ModelBuilder modelBuilder)
		{
			modelBuilder.Entity<BaseType>()
				.OwnsOne(b => b.SeriesCategory);
			modelBuilder.Entity<BaseType>()
						.HasDiscriminator(b => b.SeriesCategory)
						.HasValue(new SeriesCategory() { Series = Series.One, Category = Category.A })
						.HasValue<Series2CategoryB>(new SeriesCategory() { Series = Series.Two, Category = Category.B });
		}
	}

	public enum Series { One, Two }
	public enum Category { A, B }

	public class SeriesCategory
	{
		public Series Series { get; set; }
		public Category Category { get; set; }
	}

	public class BaseType
	{
		[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
		public int Id { get; set; }

		public SeriesCategory SeriesCategory { get; set; }
	}
	public class Series2CategoryB : BaseType { }
}

PM> Add-Migration MyFirstMigration
Build started...
Build succeeded.
System.InvalidOperationException: 'SeriesCategory' cannot be used as a property on entity type 'BaseType' because it is configured as a navigation.
   at Microsoft.EntityFrameworkCore.Metadata.Internal.InternalEntityTypeBuilder.Property(Type propertyType, String propertyName, MemberInfo memberInfo, Nullable`1 typeConfigurationSource, Nullable`1 configurationSource)
   at Microsoft.EntityFrameworkCore.Metadata.Internal.InternalEntityTypeBuilder.Property(MemberInfo memberInfo, Nullable`1 configurationSource)
   at Microsoft.EntityFrameworkCore.Metadata.Internal.InternalEntityTypeBuilder.HasDiscriminator(MemberInfo memberInfo, ConfigurationSource configurationSource)
   at Microsoft.EntityFrameworkCore.Metadata.Builders.EntityTypeBuilder`1.HasDiscriminator[TDiscriminator](Expression`1 propertyExpression)
   at MultipleDiscriminatorColumns.BloggingContext.OnModelCreating(ModelBuilder modelBuilder) in G:\Google Drive\TestProjects\InterfaceOnDerived\MultipleDiscriminatorColumns\Program.cs:line 24
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelCustomizer.Customize(ModelBuilder modelBuilder, DbContext context)
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelSource.CreateModel(DbContext context, IConventionSetBuilder conventionSetBuilder, ModelDependencies modelDependencies)
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelSource.GetModel(DbContext context, IConventionSetBuilder conventionSetBuilder, ModelDependencies modelDependencies)
   at Microsoft.EntityFrameworkCore.Internal.DbContextServices.CreateModel()
   at Microsoft.EntityFrameworkCore.Internal.DbContextServices.get_Model()
   at Microsoft.EntityFrameworkCore.Infrastructure.EntityFrameworkServicesBuilder.<>c.<TryAddCoreServices>b__7_3(IServiceProvider p)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitFactory(FactoryCallSite factoryCallSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSiteMain(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitCache(ServiceCallSite callSite, RuntimeResolverContext context, ServiceProviderEngineScope serviceProviderEngine, RuntimeResolverLock lockType)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitScopeCache(ServiceCallSite singletonCallSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitConstructor(ConstructorCallSite constructorCallSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSiteMain(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitCache(ServiceCallSite callSite, RuntimeResolverContext context, ServiceProviderEngineScope serviceProviderEngine, RuntimeResolverLock lockType)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitScopeCache(ServiceCallSite singletonCallSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.Resolve(ServiceCallSite callSite, ServiceProviderEngineScope scope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.DynamicServiceProviderEngine.<>c__DisplayClass1_0.<RealizeService>b__0(ServiceProviderEngineScope scope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngine.GetService(Type serviceType, ServiceProviderEngineScope serviceProviderEngineScope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngineScope.GetService(Type serviceType)
   at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService(IServiceProvider provider, Type serviceType)
   at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService[T](IServiceProvider provider)
   at Microsoft.EntityFrameworkCore.DbContext.get_DbContextDependencies()
   at Microsoft.EntityFrameworkCore.DbContext.get_InternalServiceProvider()
   at Microsoft.EntityFrameworkCore.DbContext.Microsoft.EntityFrameworkCore.Infrastructure.IInfrastructure<System.IServiceProvider>.get_Instance()
   at Microsoft.EntityFrameworkCore.Infrastructure.Internal.InfrastructureExtensions.GetService[TService](IInfrastructure`1 accessor)
   at Microsoft.EntityFrameworkCore.Infrastructure.AccessorExtensions.GetService[TService](IInfrastructure`1 accessor)
   at Microsoft.EntityFrameworkCore.Design.Internal.DbContextOperations.CreateContext(Func`1 factory)
   at Microsoft.EntityFrameworkCore.Design.Internal.DbContextOperations.CreateContext(String contextType)
   at Microsoft.EntityFrameworkCore.Design.Internal.MigrationsOperations.AddMigration(String name, String outputDir, String contextType, String namespace)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigrationImpl(String name, String outputDir, String contextType, String namespace)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigration.<>c__DisplayClass0_0.<.ctor>b__0()
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.<>c__DisplayClass3_0`1.<Execute>b__0()
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)
'SeriesCategory' cannot be used as a property on entity type 'BaseType' because it is configured as a navigation.

EF Core version: 5.0 RTM
Database provider: Microsoft.EntityFrameworkCore.SqlServer
Target framework: .NET 5.0 RTM
Operating system: Windows 10 Pro 20H2 x64
IDE: Visual Studio 2019 16.8.1

[ajcvickers]

@vslee This isn't currently possible. More flexible discriminator mapping is covered by #10140