Refactor to make registering model configurations public

Author: Chris Martinez

src/AspNetCore/OData/src/Asp.Versioning.OData/DependencyInjection/IApiVersioningBuilderExtensions.cs

@@ -9,7 +9,6 @@ namespace Microsoft.Extensions.DependencyInjection;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Http.Features;
 using Microsoft.AspNetCore.Mvc.ApplicationModels;
-using Microsoft.AspNetCore.Mvc.ApplicationParts;
 using Microsoft.AspNetCore.OData;
 using Microsoft.AspNetCore.OData.Routing.Template;
 using Microsoft.AspNetCore.Routing;
@@ -66,8 +65,7 @@ private static void AddServices( IServiceCollection services )
         services.TryRemoveODataService( typeof( IApplicationModelProvider ), ODataRoutingApplicationModelProviderType );
 
         var partManager = services.GetOrCreateApplicationPartManager();
-
-        ConfigureDefaultFeatureProviders( partManager );
+        var configured = partManager.ConfigureDefaultFeatureProviders();
 
         services.AddHttpContextAccessor();
         services.TryAddSingleton<VersionedODataOptions>();
@@ -84,24 +82,11 @@ private static void AddServices( IServiceCollection services )
         services.TryAddEnumerable( Singleton<MatcherPolicy, DefaultMetadataMatcherPolicy>() );
         services.TryAddEnumerable( Transient<IApplicationModelProvider, ODataApplicationModelProvider>() );
         services.TryAddEnumerable( Transient<IApplicationModelProvider, ODataMultiModelApplicationModelProvider>() );
-        services.AddModelConfigurationsAsServices( partManager );
-    }
-
-    private static T GetService<T>( this IServiceCollection services ) =>
-        (T) services.LastOrDefault( d => d.ServiceType == typeof( T ) )?.ImplementationInstance!;
-
-    private static ApplicationPartManager GetOrCreateApplicationPartManager( this IServiceCollection services )
-    {
-        var partManager = services.GetService<ApplicationPartManager>();
 
-        if ( partManager == null )
+        if ( configured )
         {
-            partManager = new ApplicationPartManager();
-            services.TryAddSingleton( partManager );
+            services.AddModelConfigurationsAsServices( partManager );
         }
-
-        partManager.ApplicationParts.Add( new AssemblyPart( typeof( ODataApiVersioningOptions ).Assembly ) );
-        return partManager;
     }
 
     [MethodImpl( MethodImplOptions.AggressiveInlining )]
@@ -148,27 +133,6 @@ private static void TryReplaceODataService(
         }
     }
 
-    private static void AddModelConfigurationsAsServices( this IServiceCollection services, ApplicationPartManager partManager )
-    {
-        var feature = new ModelConfigurationFeature();
-        var modelConfigurationType = typeof( IModelConfiguration );
-
-        partManager.PopulateFeature( feature );
-
-        foreach ( var modelConfiguration in feature.ModelConfigurations )
-        {
-            services.TryAddEnumerable( Transient( modelConfigurationType, modelConfiguration ) );
-        }
-    }
-
-    private static void ConfigureDefaultFeatureProviders( ApplicationPartManager partManager )
-    {
-        if ( !partManager.FeatureProviders.OfType<ModelConfigurationFeatureProvider>().Any() )
-        {
-            partManager.FeatureProviders.Add( new ModelConfigurationFeatureProvider() );
-        }
-    }
-
     private static object CreateInstance( this IServiceProvider services, ServiceDescriptor descriptor )
     {
         if ( descriptor.ImplementationInstance != null )

src/AspNetCore/OData/src/Asp.Versioning.OData/DependencyInjection/IServiceCollectionExtensions.cs

@@ -0,0 +1,76 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
+
+namespace Microsoft.Extensions.DependencyInjection;
+
+using Asp.Versioning.OData;
+using Microsoft.AspNetCore.Mvc.ApplicationParts;
+using Microsoft.Extensions.DependencyInjection.Extensions;
+using System.Runtime.CompilerServices;
+using static Microsoft.Extensions.DependencyInjection.ServiceDescriptor;
+
+/// <summary>
+/// Provides extension methods for <see cref="IServiceCollection"/>.
+/// </summary>
+public static class IServiceCollectionExtensions
+{
+    [MethodImpl( MethodImplOptions.AggressiveInlining )]
+    internal static T GetService<T>( this IServiceCollection services ) =>
+        (T) services.LastOrDefault( d => d.ServiceType == typeof( T ) )?.ImplementationInstance!;
+
+    internal static ApplicationPartManager GetOrCreateApplicationPartManager( this IServiceCollection services )
+    {
+        var partManager = services.GetService<ApplicationPartManager>();
+
+        if ( partManager == null )
+        {
+            partManager = new ApplicationPartManager();
+            services.TryAddSingleton( partManager );
+        }
+
+        partManager.ApplicationParts.Add( new AssemblyPart( typeof( ODataApiVersioningOptions ).Assembly ) );
+        return partManager;
+    }
+
+    internal static void AddModelConfigurationsAsServices( this IServiceCollection services, ApplicationPartManager partManager )
+    {
+        var feature = new ModelConfigurationFeature();
+        var modelConfigurationType = typeof( IModelConfiguration );
+
+        partManager.PopulateFeature( feature );
+
+        foreach ( var modelConfiguration in feature.ModelConfigurations )
+        {
+            services.TryAddEnumerable( Transient( modelConfigurationType, modelConfiguration ) );
+        }
+    }
+
+    internal static bool ConfigureDefaultFeatureProviders( this ApplicationPartManager partManager )
+    {
+        if ( partManager.FeatureProviders.OfType<ModelConfigurationFeatureProvider>().Any() )
+        {
+            return false;
+        }
+
+        partManager.FeatureProviders.Add( new ModelConfigurationFeatureProvider() );
+        return true;
+    }
+
+    /// <summary>
+    /// Registers discovered <see cref="IModelConfiguration">model configurations</see> as services in the <see cref="IServiceCollection"/>.
+    /// </summary>
+    /// <param name="services">The extended <see cref="IServiceCollection"/>.</param>
+    public static void AddModelConfigurationsAsServices( this IServiceCollection services )
+    {
+        if ( services == null )
+        {
+            throw new ArgumentNullException( nameof( services ) );
+        }
+
+        var partManager = services.GetOrCreateApplicationPartManager();
+
+        if ( ConfigureDefaultFeatureProviders( partManager ) )
+        {
+            services.AddModelConfigurationsAsServices( partManager );
+        }
+    }
+}

src/AspNetCore/OData/src/Asp.Versioning.OData/OData/ODataMultiModelApplicationModelProvider.cs

@@ -4,7 +4,6 @@
 
 namespace Asp.Versioning.OData;
 
-using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc.ApplicationModels;
 using Microsoft.AspNetCore.OData;
 using Microsoft.AspNetCore.OData.Routing.Conventions;