Configuring TPH with Enum Discriminator Throws InvalidOperationException

[Cooksauce]

There appears to be a bug when configuring by implementing IEntityTypeConfiguration<TEntity> ... order should not matter. Otherwise the ApplyConfigurationsFromAssembly(...); method can/will throw exception.

An InvalidOperationException is thrown with message The property 'Discriminator' cannot be added to type 'Base' because the type of the corresponding CLR property or field 'Direction' does not match the specified type 'string'.

This only happens when configuring a derived type before the base type and when using a property named "Discriminator" as the discriminator (below - Base.Discriminator)

Entities:

public abstract class Base
{
     public int Id { get; set; }
     public Direction Discriminator { get; set; }

     public class Config : IEntityTypeConfiguration<Base>
     {
          public void Configure(EntityTypeBuilder<Base> builder)
          {
                builder.HasDiscriminator(o => o.Discriminator)
                       .HasValue<ALeft>(Direction.Left);
          }
    }
}

public class ALeft : Base
{
     public new class Config : IEntityTypeConfiguration<ALeft>
     {
          public void Configure(EntityTypeBuilder<ALeft> builder)
          {
          }
     }
}

public enum Direction
{
     Left,
     Right
}

Configuration:

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
     base.OnModelCreating(modelBuilder);

     // Config1 - Throws exception
     modelBuilder.ApplyConfiguration(new ALeft.Config());
     modelBuilder.ApplyConfiguration(new Base.Config());


     // Config2 - Throws exception
     //modelBuilder.ApplyConfigurationsFromAssembly(typeof(DataContext).Assembly);


     // Config3 - Does not throw
     modelBuilder.ApplyConfiguration(new Base.Config());
     modelBuilder.ApplyConfiguration(new ALeft.Config());
}

Steps to reproduce

1. Open solution
2. In Package Manager Console => 'Add-Migration Initial'

Work-Arounds:

1. Configuring the abstract class first - This isn't possible when applying from assembly
2. Changing the name of the discriminator property to something other than "Discriminator"

Further technical details

EF Core version: 3.0.0
Database provider: (Npgsql - 3.0.1)
Target framework: (.NET Core 3.0)

StackTrace

System.InvalidOperationException: The property 'Discriminator' cannot be added to type 'Base' because the type of the corresponding CLR property or field 'Direction' does not match the specified type 'string'.
   at Microsoft.EntityFrameworkCore.Metadata.Internal.EntityType.AddProperty(String name, Type propertyType, MemberInfo memberInfo, Nullable`1 typeConfigurationSource, ConfigurationSource configurationSource)
   at Microsoft.EntityFrameworkCore.Metadata.Internal.EntityType.AddProperty(String name, Type propertyType, Nullable`1 typeConfigurationSource, ConfigurationSource configurationSource)
   at Microsoft.EntityFrameworkCore.Metadata.Internal.InternalEntityTypeBuilder.Property(Property existingProperty, String propertyName, Type propertyType, MemberInfo clrProperty, Nullable`1 typeConfigurationSource, Nullable`1 configurationSource)
   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(Type propertyType, String propertyName, Nullable`1 typeConfigurationSource, Nullable`1 configurationSource)
   at Microsoft.EntityFrameworkCore.Metadata.Internal.InternalEntityTypeBuilder.GetOrCreateDiscriminatorProperty(Type type, String name, Boolean fromDataAnnotation)
   at Microsoft.EntityFrameworkCore.Metadata.Internal.InternalEntityTypeBuilder.Microsoft.EntityFrameworkCore.Metadata.Builders.IConventionEntityTypeBuilder.HasDiscriminator(Type type, Boolean fromDataAnnotation)
   at Microsoft.EntityFrameworkCore.Metadata.Conventions.DiscriminatorConvention.ProcessEntityTypeBaseTypeChanged(IConventionEntityTypeBuilder entityTypeBuilder, IConventionEntityType newBaseType, IConventionEntityType oldBaseType, IConventionContext`1 context)
   at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.ConventionDispatcher.ImmediateConventionScope.OnEntityTypeBaseTypeChanged(IConventionEntityTypeBuilder entityTypeBuilder, IConventionEntityType newBaseType, IConventionEntityType previousBaseType)
   at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.ConventionDispatcher.RunVisitor.VisitOnBaseEntityTypeChanged(OnEntityTypeBaseTypeChangedNode node)
   at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.ConventionDispatcher.OnEntityTypeBaseTypeChangedNode.Accept(ConventionVisitor visitor)
   at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.ConventionDispatcher.ConventionVisitor.Visit(ConventionNode node)
   at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.ConventionDispatcher.ConventionVisitor.VisitConventionScope(ConventionScope node)
   at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.ConventionDispatcher.ConventionBatch.Run()
   at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.ConventionDispatcher.ConventionBatch.Dispose()
   at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.ConventionDispatcher.ImmediateConventionScope.OnEntityTypeAdded(IConventionEntityTypeBuilder entityTypeBuilder)
   at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.ConventionDispatcher.OnEntityTypeAdded(IConventionEntityTypeBuilder entityTypeBuilder)
   at Microsoft.EntityFrameworkCore.Metadata.Internal.Model.AddEntityType(EntityType entityType)
   at Microsoft.EntityFrameworkCore.Metadata.Internal.Model.AddEntityType(Type type, ConfigurationSource configurationSource)
   at Microsoft.EntityFrameworkCore.Metadata.Internal.InternalModelBuilder.Entity(TypeIdentity& type, ConfigurationSource configurationSource, Nullable`1 shouldBeOwned)
   at Microsoft.EntityFrameworkCore.Metadata.Internal.InternalModelBuilder.Entity(Type type, ConfigurationSource configurationSource, Nullable`1 shouldBeOwned)
   at Microsoft.EntityFrameworkCore.ModelBuilder.Entity[TEntity]()
   at Microsoft.EntityFrameworkCore.ModelBuilder.ApplyConfiguration[TEntity](IEntityTypeConfiguration`1 configuration)
   at EnumAsDiscriminatorBug.Data.DataContext.OnModelCreating(ModelBuilder modelBuilder) in *redacted*\source\repos\EnumAsDiscriminatorBug\Data\DataContext.cs:line 21
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelCustomizer.Customize(ModelBuilder modelBuilder, DbContext context)
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelSource.CreateModel(DbContext context, IConventionSetBuilder conventionSetBuilder)
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelSource.<>c__DisplayClass5_0.<GetModel>b__1()
   at System.Lazy`1.ViaFactory(LazyThreadSafetyMode mode)
   at System.Lazy`1.ExecutionAndPublication(LazyHelper executionAndPublication, Boolean useDefaultConstructor)
   at System.Lazy`1.CreateValue()
   at System.Lazy`1.get_Value()
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelSource.GetModel(DbContext context, IConventionSetBuilder conventionSetBuilder)
   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)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigrationImpl(String name, String outputDir, String contextType)
   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)

[ajcvickers]

Likely duplicate of #15553

[Cooksauce]

@ajcvickers I saw that issue. In my opinion, I wouldn't classify this as a duplicate. #15553 is an issue with relationships between two hierarchies, while this is a just a single hierarchy and the issue is based around the discriminator name and the order of configuration.

I have a repro which demonstrates the bug without any other entities than those above, so I'm 100% sure this isn't caused by relationships between hierarchies like #15553. It appears to be strictly the name of the discriminator combined with configuring the derived type first.

The fix for one may fix the other, but I wouldn't say they're the same issue.

[Cooksauce]

Repro here: https://github.com/Cooksauce/EnumDiscriminatorBug

[AndriySvyryd]

Doesn't repro in 3.1.1