[Fixes #4087] Add AddViewComponentsAsServices() and ServiceBasedViewComponentActivator

Author: javiercn

src/Microsoft.AspNetCore.Mvc.ViewFeatures/DependencyInjection/MvcViewFeaturesMvcBuilderExtensions.cs

@@ -2,7 +2,10 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Linq;
 using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Mvc.ViewComponents;
+using Microsoft.Extensions.DependencyInjection.Extensions;
 
 namespace Microsoft.Extensions.DependencyInjection
 {
@@ -33,5 +36,20 @@ public static IMvcBuilder AddViewOptions(
             builder.Services.Configure(setupAction);
             return builder;
         }
+
+        public static IMvcBuilder AddViewComponentsAsServices(this IMvcBuilder builder)
+        {
+            var feature = new ViewComponentsFeature();
+            builder.Manager.PopulateFeature(feature);
+
+            foreach (var viewComponent in feature.ViewComponents.Select(vc => vc.AsType()))
+            {
+                builder.Services.TryAddTransient(viewComponent, viewComponent);
+            }
+
+            builder.Services.Replace(ServiceDescriptor.Transient<IViewComponentActivator, ServiceBasedViewComponentActivator>());
+
+            return builder;
+        }
     }
 }

src/Microsoft.AspNetCore.Mvc.ViewFeatures/DependencyInjection/MvcViewFeaturesMvcCoreBuilderExtensions.cs

@@ -3,7 +3,9 @@
 
 using System;
 using System.Buffers;
+using System.Linq;
 using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Mvc.ApplicationParts;
 using Microsoft.AspNetCore.Mvc.Controllers;
 using Microsoft.AspNetCore.Mvc.Formatters;
 using Microsoft.AspNetCore.Mvc.Rendering;
@@ -26,10 +28,19 @@ public static IMvcCoreBuilder AddViews(this IMvcCoreBuilder builder)
             }
 
             builder.AddDataAnnotations();
+            AddViewApplicationPartsProviders(builder.Manager);
             AddViewServices(builder.Services);
             return builder;
         }
 
+        private static void AddViewApplicationPartsProviders(ApplicationPartManager manager)
+        {
+            if (!manager.Providers.OfType<ViewComponentsFeatureProvider>().Any())
+            {
+                manager.Providers.Add(new ViewComponentsFeatureProvider());
+            }
+        }
+
         public static IMvcCoreBuilder AddViews(
             this IMvcCoreBuilder builder,
             Action<MvcViewOptions> setupAction)

src/Microsoft.AspNetCore.Mvc.ViewFeatures/ViewComponents/DefaultViewComponentDescriptorProvider.cs

@@ -6,6 +6,7 @@
 using System.Linq;
 using System.Reflection;
 using System.Threading.Tasks;
+using Microsoft.AspNetCore.Mvc.ApplicationParts;
 using Microsoft.AspNetCore.Mvc.Infrastructure;
 using Microsoft.AspNetCore.Mvc.ViewFeatures;
 
@@ -18,64 +19,47 @@ public class DefaultViewComponentDescriptorProvider : IViewComponentDescriptorPr
     {
         private const string AsyncMethodName = "InvokeAsync";
         private const string SyncMethodName = "Invoke";
-        private readonly IAssemblyProvider _assemblyProvider;
+        private readonly ApplicationPartManager _manager;
 
         /// <summary>
         /// Creates a new <see cref="DefaultViewComponentDescriptorProvider"/>.
         /// </summary>
-        /// <param name="assemblyProvider">The <see cref="IAssemblyProvider"/>.</param>
-        public DefaultViewComponentDescriptorProvider(IAssemblyProvider assemblyProvider)
+        /// <param name="manager">The <see cref="ApplicationPartManager"/>.</param>
+        public DefaultViewComponentDescriptorProvider(ApplicationPartManager manager)
         {
-            _assemblyProvider = assemblyProvider;
+            if (manager == null)
+            {
+                throw new ArgumentNullException(nameof(manager));
+            }
+
+            _manager = manager;
         }
 
         /// <inheritdoc />
         public virtual IEnumerable<ViewComponentDescriptor> GetViewComponents()
         {
-            var types = GetCandidateTypes();
-
-            return types
-                .Where(IsViewComponentType)
-                .Select(CreateDescriptor);
+            return GetCandidateTypes().Select(CreateDescriptor);
         }
 
         /// <summary>
-        /// Gets the candidate <see cref="TypeInfo"/> instances. The results of this will be provided to
-        /// <see cref="IsViewComponentType"/> for filtering.
+        /// Gets the candidate <see cref="TypeInfo"/> instances provided by the <see cref="ApplicationPartManager"/>.
         /// </summary>
         /// <returns>A list of <see cref="TypeInfo"/> instances.</returns>
         protected virtual IEnumerable<TypeInfo> GetCandidateTypes()
         {
-            var assemblies = _assemblyProvider.CandidateAssemblies;
-            return assemblies.SelectMany(a => a.ExportedTypes).Select(t => t.GetTypeInfo());
-        }
-
-        /// <summary>
-        /// Determines whether or not the given <see cref="TypeInfo"/> is a view component class.
-        /// </summary>
-        /// <param name="typeInfo">The <see cref="TypeInfo"/>.</param>
-        /// <returns>
-        /// <c>true</c> if <paramref name="typeInfo"/>represents a view component class, otherwise <c>false</c>.
-        /// </returns>
-        protected virtual bool IsViewComponentType(TypeInfo typeInfo)
-        {
-            if (typeInfo == null)
-            {
-                throw new ArgumentNullException(nameof(typeInfo));
-            }
-
-            return ViewComponentConventions.IsComponent(typeInfo);
+            var feature = new ViewComponentsFeature();
+            _manager.PopulateFeature(feature);
+            return feature.ViewComponents;
         }
 
         private static ViewComponentDescriptor CreateDescriptor(TypeInfo typeInfo)
         {
-            var type = typeInfo.AsType();
             var candidate = new ViewComponentDescriptor
             {
                 FullName = ViewComponentConventions.GetComponentFullName(typeInfo),
                 ShortName = ViewComponentConventions.GetComponentName(typeInfo),
                 TypeInfo = typeInfo,
-                MethodInfo = FindMethod(type)
+                MethodInfo = FindMethod(typeInfo.AsType())
             };
 
             return candidate;

src/Microsoft.AspNetCore.Mvc.ViewFeatures/ViewComponents/ServiceBasedViewComponentActivator.cs

@@ -0,0 +1,27 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace Microsoft.AspNetCore.Mvc.ViewComponents
+{
+    public class ServiceBasedViewComponentActivator : IViewComponentActivator
+    {
+        public object Create(ViewComponentContext context)
+        {
+            if (context == null)
+            {
+                throw new ArgumentNullException(nameof(context));
+            }
+
+            var controllerType = context.ViewComponentDescriptor.TypeInfo.AsType();
+
+            return context.ViewContext.HttpContext.RequestServices.GetRequiredService(controllerType);
+        }
+
+        public virtual void Release(ViewComponentContext context, object viewComponent)
+        {
+        }
+    }
+}

src/Microsoft.AspNetCore.Mvc.ViewFeatures/ViewComponents/ViewComponentsFeature.cs

@@ -0,0 +1,13 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+using System.Threading.Tasks;
+
+namespace Microsoft.AspNetCore.Mvc.ViewComponents
+{
+    public class ViewComponentsFeature
+    {
+        public IList<TypeInfo> ViewComponents { get; } = new List<TypeInfo>();
+    }
+}

src/Microsoft.AspNetCore.Mvc.ViewFeatures/ViewComponents/ViewComponentsFeatureProvider.cs

@@ -0,0 +1,22 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Mvc.ApplicationParts;
+
+namespace Microsoft.AspNetCore.Mvc.ViewComponents
+{
+    public class ViewComponentsFeatureProvider : IApplicationFeatureProvider<ViewComponentsFeature>
+    {
+        public void GetFeature(IEnumerable<ApplicationPart> parts, ViewComponentsFeature feature)
+        {
+            foreach (var type in parts.OfType<IExportTypes>().SelectMany(p => p.Types))
+            {
+                if (ViewComponentConventions.IsComponent(type) && ! feature.ViewComponents.Contains(type))
+                {
+                    feature.ViewComponents.Add(type);
+                }
+            }
+        }
+    }
+}

test/Microsoft.AspNetCore.Mvc.FunctionalTests/MvcTestFixture.cs

@@ -10,6 +10,8 @@
 using Microsoft.AspNetCore.Mvc.ApplicationParts;
 using Microsoft.AspNetCore.Mvc.Controllers;
 using Microsoft.AspNetCore.Mvc.Infrastructure;
+
+using Microsoft.AspNetCore.Mvc.ViewComponents;
 using Microsoft.AspNetCore.TestHost;
 using Microsoft.AspNetCore.Testing;
 using Microsoft.Extensions.DependencyInjection;
@@ -72,7 +74,10 @@ protected virtual void InitializeServices(IServiceCollection services)
 
             var manager = new ApplicationPartManager();
             manager.ApplicationParts.Add(new AssemblyPart(startupAssembly));
+
             manager.FeatureProviders.Add(new ControllerFeatureProvider());
+            manager.FeatureProviders.Add(new ViewComponentsFeatureProvider());
+
             services.AddSingleton(manager);
         }