Add ITagHelperComponentManager

src/Microsoft.AspNetCore.Mvc.Razor/DependencyInjection/MvcRazorMvcCoreBuilderExtensions.cs

@@ -8,6 +8,7 @@
 using Microsoft.AspNetCore.Mvc.Razor.Compilation;
 using Microsoft.AspNetCore.Mvc.Razor.Extensions;
 using Microsoft.AspNetCore.Mvc.Razor.Internal;
+using Microsoft.AspNetCore.Mvc.Razor.TagHelpers;
 using Microsoft.AspNetCore.Mvc.Rendering;
 using Microsoft.AspNetCore.Razor.Language;
 using Microsoft.AspNetCore.Razor.TagHelpers;
@@ -187,6 +188,9 @@ internal static void AddRazorViewEngineServices(IServiceCollection services)
             services.TryAddSingleton<ITagHelperActivator, DefaultTagHelperActivator>();
             services.TryAddSingleton<ITagHelperFactory, DefaultTagHelperFactory>();
 
+            // TagHelperComponents manager
+            services.TryAddScoped<ITagHelperComponentManager, TagHelperComponentManager>();
+
             // Consumed by the Cache tag helper to cache results across the lifetime of the application.
             services.TryAddSingleton<IMemoryCache, MemoryCache>();
         }

src/Microsoft.AspNetCore.Mvc.Razor/Internal/TagHelperComponentManager.cs

@@ -0,0 +1,33 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using Microsoft.AspNetCore.Mvc.Razor.TagHelpers;
+using Microsoft.AspNetCore.Razor.TagHelpers;
+
+namespace Microsoft.AspNetCore.Mvc.Razor.Internal
+{
+    /// <summary>
+    /// The default implementation of the <see cref="ITagHelperComponentManager"/>.
+    /// </summary>
+    public class TagHelperComponentManager : ITagHelperComponentManager
+    {
+        /// <summary>
+        /// Creates a new <see cref="TagHelperComponentManager"/>.
+        /// </summary>
+        /// <param name="tagHelperComponents">The collection of <see cref="ITagHelperComponent"/>s.</param>
+        public TagHelperComponentManager(IEnumerable<ITagHelperComponent> tagHelperComponents)
+        {
+            if (tagHelperComponents == null)
+            {
+                throw new ArgumentNullException(nameof(tagHelperComponents));
+            }
+
+            Components = new List<ITagHelperComponent>(tagHelperComponents);
+        }
+
+        /// <inheritdoc />
+        public ICollection<ITagHelperComponent> Components { get; }
+    }
+}

src/Microsoft.AspNetCore.Mvc.Razor/TagHelpers/BodyTagHelper.cs

@@ -1,7 +1,6 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
-using System.Collections.Generic;
 using System.ComponentModel;
 using Microsoft.AspNetCore.Razor.TagHelpers;
 using Microsoft.Extensions.Logging;
@@ -18,10 +17,11 @@ public class BodyTagHelper : TagHelperComponentTagHelper
         /// <summary>
         /// Creates a new <see cref="BodyTagHelper"/>.
         /// </summary>
-        /// <param name="components">The list of <see cref="ITagHelperComponent"/>.</param>
+        /// <param name="manager">The <see cref="ITagHelperComponentManager"/> which contains the collection
+        /// of <see cref="ITagHelperComponent"/>s.</param>
         /// <param name="loggerFactory">The <see cref="ILoggerFactory"/>.</param>
-        public BodyTagHelper(IEnumerable<ITagHelperComponent> components, ILoggerFactory loggerFactory)
-            : base(components, loggerFactory)
+        public BodyTagHelper(ITagHelperComponentManager manager, ILoggerFactory loggerFactory)
+            : base(manager, loggerFactory)
         {
         }
     }

src/Microsoft.AspNetCore.Mvc.Razor/TagHelpers/HeadTagHelper.cs

@@ -1,7 +1,6 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
-using System.Collections.Generic;
 using System.ComponentModel;
 using Microsoft.AspNetCore.Razor.TagHelpers;
 using Microsoft.Extensions.Logging;
@@ -18,10 +17,11 @@ public class HeadTagHelper : TagHelperComponentTagHelper
         /// <summary>
         /// Creates a new <see cref="HeadTagHelper"/>.
         /// </summary>
-        /// <param name="components">The list of <see cref="ITagHelperComponent"/>.</param>
+        /// <param name="manager">The <see cref="ITagHelperComponentManager"/> which contains the collection
+        /// of <see cref="ITagHelperComponent"/>s.</param>
         /// <param name="loggerFactory">The <see cref="ILoggerFactory"/>.</param>
-        public HeadTagHelper(IEnumerable<ITagHelperComponent> components, ILoggerFactory loggerFactory)
-            : base(components, loggerFactory)
+        public HeadTagHelper(ITagHelperComponentManager manager, ILoggerFactory loggerFactory)
+            : base(manager, loggerFactory)
         {
         }
     }

src/Microsoft.AspNetCore.Mvc.Razor/TagHelpers/ITagHelperComponentManager.cs

@@ -0,0 +1,21 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Collections.Generic;
+using Microsoft.AspNetCore.Razor.TagHelpers;
+
+namespace Microsoft.AspNetCore.Mvc.Razor.TagHelpers
+{
+    /// <summary>
+    /// An implementation of this interface provides the collection of <see cref="ITagHelperComponent"/>s
+    /// that will be used by <see cref="TagHelperComponentTagHelper"/>s.
+    /// </summary>
+    public interface ITagHelperComponentManager
+    {
+        /// <summary>
+        /// Gets the collection of <see cref="ITagHelperComponent"/>s that will be used by
+        /// <see cref="TagHelperComponentTagHelper"/>s.
+        /// </summary>
+        ICollection<ITagHelperComponent> Components { get; }
+    }
+}

src/Microsoft.AspNetCore.Mvc.Razor/TagHelpers/TagHelperComponentTagHelper.cs

@@ -11,38 +11,46 @@
 
 namespace Microsoft.AspNetCore.Mvc.Razor.TagHelpers
 {
+    /// <summary>
+    /// Initializes and processes the <see cref="ITagHelperComponent"/>s added to the 
+    /// <see cref="ITagHelperComponentManager.Components"/> in the specified order.
+    /// </summary>
     public abstract class TagHelperComponentTagHelper : TagHelper
     {
         private readonly ILogger _logger;
 
         private IEnumerable<ITagHelperComponent> _components;
 
         /// <summary>
-        /// Creates a new <see cref="TagHelperComponentTagHelper"/>.
+        /// Creates a new <see cref="TagHelperComponentTagHelper"/> and orders the 
+        /// the collection of <see cref="ITagHelperComponent"/>s in <see cref="ITagHelperComponentManager.Components"/>.
         /// </summary>
-        /// <param name="components">The list of <see cref="ITagHelperComponent"/>.</param>
+        /// <param name="manager">The <see cref="ITagHelperComponentManager"/> which contains the collection
+        /// of <see cref="ITagHelperComponent"/>s.</param>
         /// <param name="loggerFactory">The <see cref="ILoggerFactory"/>.</param>
-        public TagHelperComponentTagHelper(IEnumerable<ITagHelperComponent> components,
+        /// <remarks>The <see cref="ITagHelperComponentManager.Components"/> are ordered after the 
+        /// creation of the <see cref="ITagHelperComponentManager"/> to position the <see cref="ITagHelperComponent"/>s
+        /// added from controllers and views correctly.</remarks>
+        public TagHelperComponentTagHelper(ITagHelperComponentManager manager,
             ILoggerFactory loggerFactory)
         {
-            if (components == null)
+            if (manager == null)
             {
-                throw new ArgumentNullException(nameof(components));
+                throw new ArgumentNullException(nameof(manager));
             }
 
             if (loggerFactory == null)
             {
                 throw new ArgumentNullException(nameof(loggerFactory));
             }
 
-            _components = components;
+            _components = manager.Components.OrderBy(p => p.Order).ToArray();
             _logger = loggerFactory.CreateLogger(GetType());
         }
 
         /// <inheritdoc />
         public override void Init(TagHelperContext context)
         {
-            _components = _components.OrderBy(p => p.Order);
             foreach (var component in _components)
             {
                 component.Init(context);

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

@@ -61,6 +61,30 @@ public async Task InjectsTestBodyTagHelperComponent()
             // Assert
             Assert.Equal(HttpStatusCode.OK, response.StatusCode);
 
+#if GENERATE_BASELINES
+            ResourceFile.UpdateFile(_resourcesAssembly, outputFile, expectedContent, responseContent);
+#else
+            Assert.Equal(expectedContent, responseContent, ignoreLineEndingDifferences: true);
+#endif
+        }
+
+        [Fact]
+        public async Task AddTestTagHelperComponent_FromController()
+        {
+            // Arrange
+            var url = "http://localhost/AddTagHelperComponent/AddComponent";
+            var request = new HttpRequestMessage(HttpMethod.Get, url);
+            var outputFile = "compiler/resources/RazorWebSite.AddTagHelperComponent.AddComponent.html";
+            var expectedContent =
+                await ResourceFile.ReadResourceAsync(_resourcesAssembly, outputFile, sourceFile: false);
+
+            // Act
+            var response = await Client.SendAsync(request);
+            var responseContent = await response.Content.ReadAsStringAsync();
+
+            // Assert
+            Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+
 #if GENERATE_BASELINES
             ResourceFile.UpdateFile(_resourcesAssembly, outputFile, expectedContent, responseContent);
 #else

test/Microsoft.AspNetCore.Mvc.FunctionalTests/compiler/resources/RazorWebSite.AddTagHelperComponent.AddComponent.html

@@ -0,0 +1,6 @@
+<head inject>
+Hello from Head Tag Helper Component
+<script>'This was injected!!'</script></head>
+<body inject>
+Hello from Body Tag Helper Component
+Processed TagHelperComponent added from controller.<script>'This was injected!!'</script>Processed TagHelperComponent added from view.</body>