Support enum navigations on owned types

[TAGC]

Consider we define a domain like this:

public class Customer
{
    public int Id { get; set; }
    public Address Address { get; set; }
}

public class Address
{
    public CountryCode CountryCode { get; set; }
}

public enum CountryCode
{
    AF = 4,
    AL = 8
    // ...
}

We configure Customer to "own" an instance of Address, and ideally want Address to have a foreign key constraint on a CountryCode enum lookup table that gets generated by this library:

 protected override void OnModelCreating(ModelBuilder modelBuilder)
 {
    modelBuilder.Entity<Customer>().OwnsOne(x => x.Address).WithOwner();
    modelBuilder.ConfigureEnumLookup(EnumLookupOptions.Default.SetNamingScheme(x => x.Pascalize()));
}

However, trying to create a migration for this causes the following exception to be thrown:

PM> Add-Migration InitialCreate
Build started...
Build succeeded.
System.InvalidOperationException: The type 'experiment.Data.CommissionsContext+Address' cannot be configured as non-owned because an owned entity type with the same name already exists.
   at Microsoft.EntityFrameworkCore.Metadata.Internal.InternalModelBuilder.Entity(TypeIdentity& type, ConfigurationSource configurationSource, Nullable`1 shouldBeOwned)
   at Microsoft.EntityFrameworkCore.Metadata.Internal.InternalModelBuilder.Entity(String name, ConfigurationSource configurationSource, Nullable`1 shouldBeOwned)
   at Microsoft.EntityFrameworkCore.ModelBuilder.Entity(String name)
   at SpatialFocus.EntityFrameworkCore.Extensions.EnumLookupExtension.ConfigureEnumLookup(ModelBuilder modelBuilder, EnumLookupOptions enumOptions)
   at experiment.Data.CommissionsContext.OnModelCreating(ModelBuilder modelBuilder) in C:\Projects\experiment\Data\CommissionsContext.cs:line 46
   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.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)
The type 'experiment.Data.CommissionsContext+Address' cannot be configured as non-owned because an owned entity type with the same name already exists.

The reason seems to be because of this code in the library, which would try to configure Address even though it is owned by Company and can only be configured through an OwnedNavigationBuilder:

EntityFrameworkCore.Extensions/src/SpatialFocus.EntityFrameworkCore.Extensions/EnumLookupExtension.cs

Lines 71 to 76 in dc2f146

	modelBuilder.Entity(entityType.Name)
	.HasOne(concreteType)
	.WithMany()
	.HasPrincipalKey(keyName)
	.HasForeignKey(property.Name)
	.OnDelete(enumOptions.DeleteBehavior);

To support enum properties on owned types, one fix might be to check if the type is owned and skipping configuration on it if that is the case. One way I've found to do this after some quick digging was the following:

bool IsOwned(IEntityType entityType)
{
    return entityType.FindOwnership() != null;
}

If the library bypasses configuration of owned types, it might allow the relationship to be manually configured. After playing around for some time, I found this sort of worked:

modelBuilder.Entity<Customer>().OwnsOne(x => x.Address, addressBuilder =>
{
    var enumLookupType = typeof(EnumWithNumberLookup<CountryCode>);
    modelBuilder.Entity(enumLookupType).ToTable(nameof(CountryCode));

    addressBuilder.WithOwner();
    addressBuilder.HasOne(enumLookupType)
        .WithMany()
        .HasPrincipalKey("Id")
        .HasForeignKey("CountryCode")
        .OnDelete(DeleteBehavior.Cascade);
});

This produces the following migration:

public partial class InitialCreate : Migration
{
    protected override void Up(MigrationBuilder migrationBuilder)
    {
        migrationBuilder.CreateTable(
            name: "CountryCode",
            columns: table => new
            {
                Id = table.Column<int>(nullable: false),
                Name = table.Column<string>(nullable: true)
            },
            constraints: table =>
            {
                table.PrimaryKey("PK_CountryCode", x => x.Id);
            });

        migrationBuilder.CreateTable(
            name: "Customers",
            columns: table => new
            {
                Id = table.Column<int>(nullable: false)
                    .Annotation("SqlServer:Identity", "1, 1"),
                Address_CountryCode = table.Column<int>(nullable: true)
            },
            constraints: table =>
            {
                table.PrimaryKey("PK_Customers", x => x.Id);
                table.ForeignKey(
                    name: "FK_Customers_CountryCode_Address_CountryCode",
                    column: x => x.Address_CountryCode,
                    principalTable: "CountryCode",
                    principalColumn: "Id",
                    onDelete: ReferentialAction.Cascade);
            });

        migrationBuilder.CreateIndex(
            name: "IX_Customers_Address_CountryCode",
            table: "Customers",
            column: "Address_CountryCode");
    }

    protected override void Down(MigrationBuilder migrationBuilder)
    {
        migrationBuilder.DropTable(
            name: "Customers");

        migrationBuilder.DropTable(
            name: "CountryCode");
    }
}

Represented diagrammatically:

Do you think it would be feasible to improve support for owned types? I guess this would involve three parts:

1. Bypassing navigation configuration for owned types (as mentioned above). You'd still do everything else though (i.e. setting up the schema for the enum lookup table and populating it).

2. Adding some sort of utility method that simplifies manual configuration of foreign key constraints from owned types onto enum lookup types.

3. Documenting this in the README/samples/etc.

[pergerch]

Thank you for the time spent on investigating the issue. We have implemented your proposed changes.

Owned entities will be skipped in the initial run of ConfigureEnumLookup and will need to be configured seperately on the OwnedNavigationBuilder.

EntityFrameworkCore.Extensions/samples/SpatialFocus.EntityFrameworkCore.Extensions.SQLiteDemo/Data/DemoContext.cs

Lines 42 to 47 in fa2a51d

	modelBuilder.Entity<Product>()
	.OwnsMany<Review>(nameof(Product.Reviews),
	builder =>
	{
	builder.ConfigureOwnedEnumLookup(EnumLookupOptions.Default.Pluralize().UseStringAsIdentifier(), modelBuilder);
	});

Please test the changes with your project either using the latest source or the new NuGet package 2.1.0-beta1

[TAGC]

I tried this out, it seems to work really well - thanks for implementing this, I appreciate it.