Initialize ViewContext for TagHelperComponentTagHelper (#7326)

Addresses #7017

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

@@ -175,8 +175,10 @@ namespace Microsoft.Extensions.DependencyInjection
             // This caches Razor page activation details that are valid for the lifetime of the application.
             services.TryAddSingleton<IRazorPageActivator, RazorPageActivator>();
 
-            // Only want one ITagHelperActivator so it can cache Type activation information. Types won't conflict.
+            // Only want one ITagHelperActivator and ITagHelperComponentPropertyActivator so it can cache Type activation information. Types won't conflict.
             services.TryAddSingleton<ITagHelperActivator, DefaultTagHelperActivator>();
+            services.TryAddSingleton<ITagHelperComponentPropertyActivator, TagHelperComponentPropertyActivator>();
+
             services.TryAddSingleton<ITagHelperFactory, DefaultTagHelperFactory>();
 
             // TagHelperComponents manager

src/Microsoft.AspNetCore.Mvc.Razor/TagHelpers/ITagHelperComponentPropertyActivator.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 Microsoft.AspNetCore.Mvc.Rendering;
+using Microsoft.AspNetCore.Razor.TagHelpers;
+
+namespace Microsoft.AspNetCore.Mvc.Razor.TagHelpers
+{
+    /// <summary>
+    /// Provides methods to activate properties of <see cref="ITagHelperComponent"/>s.
+    /// </summary>
+    public interface ITagHelperComponentPropertyActivator
+    {
+        /// <summary>
+        /// Activates properties of the <paramref name="tagHelperComponent"/>.
+        /// </summary>
+        /// <param name="context">The <see cref="ViewContext"/> for the executing view.</param>
+        /// <param name="tagHelperComponent">The <see cref="ITagHelperComponent"/> to activate properties of.</param>
+        void Activate(ViewContext context, ITagHelperComponent tagHelperComponent);
+    }
+}

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

@@ -0,0 +1,60 @@
+// 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.Concurrent;
+using System.Reflection;
+using Microsoft.AspNetCore.Mvc.Rendering;
+using Microsoft.AspNetCore.Mvc.ViewFeatures;
+using Microsoft.AspNetCore.Razor.TagHelpers;
+using Microsoft.Extensions.Internal;
+
+namespace Microsoft.AspNetCore.Mvc.Razor.TagHelpers
+{
+    /// <summary>
+    /// Default implementation of <see cref="ITagHelperComponentPropertyActivator"/>.
+    /// </summary>
+    internal class TagHelperComponentPropertyActivator : ITagHelperComponentPropertyActivator
+    {
+        private readonly ConcurrentDictionary<Type, PropertyActivator<ViewContext>[]> _propertiesToActivate;
+        private readonly Func<Type, PropertyActivator<ViewContext>[]> _getPropertiesToActivate = GetPropertiesToActivate;
+        private static readonly Func<PropertyInfo, PropertyActivator<ViewContext>> _createActivateInfo = CreateActivateInfo;
+
+        public TagHelperComponentPropertyActivator()
+        {
+            _propertiesToActivate = new ConcurrentDictionary<Type, PropertyActivator<ViewContext>[]>();
+        }
+
+        /// <inheritdoc />
+        public void Activate(ViewContext context, ITagHelperComponent tagHelperComponent)
+        {
+            if (context == null)
+            {
+                throw new ArgumentNullException(nameof(context));
+            }
+
+            var propertiesToActivate = _propertiesToActivate.GetOrAdd(
+                tagHelperComponent.GetType(),
+                _getPropertiesToActivate);
+
+            for (var i = 0; i < propertiesToActivate.Length; i++)
+            {
+                var activateInfo = propertiesToActivate[i];
+                activateInfo.Activate(tagHelperComponent, context);
+            }
+        }
+
+        private static PropertyActivator<ViewContext> CreateActivateInfo(PropertyInfo property)
+        {
+            return new PropertyActivator<ViewContext>(property, viewContext => viewContext);
+        }
+
+        private static PropertyActivator<ViewContext>[] GetPropertiesToActivate(Type type)
+        {
+            return PropertyActivator<ViewContext>.GetPropertiesToActivate(
+                type,
+                typeof(ViewContextAttribute),
+                _createActivateInfo);
+        }
+    }
+}

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

@@ -6,7 +6,10 @@ using System.Collections.Generic;
 using System.Linq;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Mvc.Razor.Internal;
+using Microsoft.AspNetCore.Mvc.Rendering;
+using Microsoft.AspNetCore.Mvc.ViewFeatures;
 using Microsoft.AspNetCore.Razor.TagHelpers;
+using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
 
 namespace Microsoft.AspNetCore.Mvc.Razor.TagHelpers
@@ -18,7 +21,6 @@ namespace Microsoft.AspNetCore.Mvc.Razor.TagHelpers
     public abstract class TagHelperComponentTagHelper : TagHelper
     {
         private readonly ILogger _logger;
-
         private readonly IEnumerable<ITagHelperComponent> _components;
 
         /// <summary>
@@ -49,11 +51,28 @@ namespace Microsoft.AspNetCore.Mvc.Razor.TagHelpers
             _logger = loggerFactory.CreateLogger(GetType());
         }
 
+        /// <summary>
+        /// Activates the <see cref="ViewContext"/> property of all the <see cref="ITagHelperComponentManager.Components"/>.
+        /// </summary>
+        [HtmlAttributeNotBound]
+        public ITagHelperComponentPropertyActivator PropertyActivator { get; set; }
+
+        [ViewContext]
+        [HtmlAttributeNotBound]
+        public ViewContext ViewContext { get; set; }
+
         /// <inheritdoc />
         public override void Init(TagHelperContext context)
         {
+            if (PropertyActivator == null)
+            {
+                var serviceProvider = ViewContext.HttpContext.RequestServices;
+                PropertyActivator = serviceProvider.GetRequiredService<ITagHelperComponentPropertyActivator>();
+            }
+
             foreach (var component in _components)
             {
+                PropertyActivator.Activate(ViewContext, component);
                 component.Init(context);
                 if (_logger.IsEnabled(LogLevel.Debug))
                 {

test/Microsoft.AspNetCore.Mvc.FunctionalTests/compiler/resources/RazorWebSite.TagHelperComponent.Body.html

@@ -1,3 +1,4 @@
 <body inject="true">
 Hello from Body Tag Helper Component
+<p>NewValue</p>
 <script>'This was injected!!'</script></body>

test/Microsoft.AspNetCore.Mvc.Razor.Test/TagHelpers/TagHelperComponentPropertyActivatorTest.cs

@@ -0,0 +1,63 @@
+// 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.Threading.Tasks;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Mvc.Rendering;
+using Microsoft.AspNetCore.Mvc.ViewFeatures;
+using Microsoft.AspNetCore.Razor.TagHelpers;
+using Microsoft.Extensions.DependencyInjection;
+using Moq;
+using Xunit;
+
+namespace Microsoft.AspNetCore.Mvc.Razor.TagHelpers
+{
+    public class TagHelperComponentPropertyActivatorTest
+    {
+        [Fact]
+        public void Activate_InitializesViewContext()
+        {
+            // Arrange
+            var tagHelperComponent = new TestTagHelperComponent();
+            var viewContext = CreateViewContext();
+
+            var propertyActivator = new TagHelperComponentPropertyActivator();
+
+            // Act
+            propertyActivator.Activate(viewContext, tagHelperComponent);
+
+            // Assert
+            Assert.Same(viewContext, tagHelperComponent.ViewContext);
+        }
+
+        private class TestTagHelperComponent : ITagHelperComponent
+        {
+            public int Order => 1;
+
+            [ViewContext]
+            public ViewContext ViewContext { get; set; }
+
+            public void Init(TagHelperContext context)
+            {
+            }
+
+            public Task ProcessAsync(TagHelperContext context, TagHelperOutput output)
+            {
+                return Task.CompletedTask;
+            }
+        }
+
+        private static ViewContext CreateViewContext()
+        {
+            var httpContext = new DefaultHttpContext()
+            {
+                RequestServices = new ServiceCollection()
+                .AddSingleton<ITagHelperComponentPropertyActivator>(new TagHelperComponentPropertyActivator())
+                .BuildServiceProvider()
+            };
+
+            var viewContext = Mock.Of<ViewContext>(vc => vc.HttpContext == httpContext);
+            return viewContext;
+        }
+    }
+}

test/Microsoft.AspNetCore.Mvc.Razor.Test/TagHelpers/TagHelperComponentTagHelperTest.cs

@@ -5,11 +5,15 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Threading.Tasks;
+using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc.Razor.Internal;
+using Microsoft.AspNetCore.Mvc.Rendering;
 using Microsoft.AspNetCore.Razor.TagHelpers;
+using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Logging.Abstractions;
 using Microsoft.Extensions.Logging.Testing;
+using Moq;
 using Xunit;
 
 namespace Microsoft.AspNetCore.Mvc.Razor.TagHelpers
@@ -28,7 +32,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.TagHelpers
                 uniqueId: "test");
 
             var incrementer = 0;
-            var testTagHelperComponentManager = new TagHelperComponentManager(new []
+            var testTagHelperComponentManager = new TagHelperComponentManager(new[]
             {
                 new CallbackTagHelperComponent(
                     order: 2,
@@ -83,7 +87,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.TagHelpers
                     new DefaultTagHelperContent()));
 
             var incrementer = 0;
-            var testTagHelperComponentManager = new TagHelperComponentManager(new []
+            var testTagHelperComponentManager = new TagHelperComponentManager(new[]
             {
                 new CallbackTagHelperComponent(
                     order: 2,
@@ -169,7 +173,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.TagHelpers
                 getChildContentAsync: (useCachedResult, encoder) => Task.FromResult<TagHelperContent>(
                     new DefaultTagHelperContent()));
 
-            var testTagHelperComponentManager = new TagHelperComponentManager(new []
+            var testTagHelperComponentManager = new TagHelperComponentManager(new[]
             {
                 new TestTagHelperComponent()
             });
@@ -200,7 +204,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.TagHelpers
                 getChildContentAsync: (useCachedResult, encoder) => Task.FromResult<TagHelperContent>(
                     new DefaultTagHelperContent()));
 
-            var testTagHelperComponentManager = new TagHelperComponentManager(new []
+            var testTagHelperComponentManager = new TagHelperComponentManager(new[]
             {
                 new TestTagHelperComponent()
             });
@@ -235,7 +239,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.TagHelpers
                 getChildContentAsync: (useCachedResult, encoder) => Task.FromResult<TagHelperContent>(
                     new DefaultTagHelperContent()));
 
-            var testTagHelperComponentManager = new TagHelperComponentManager(new []
+            var testTagHelperComponentManager = new TagHelperComponentManager(new[]
             {
                 new TestTagHelperComponent()
             });
@@ -268,7 +272,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.TagHelpers
                 getChildContentAsync: (useCachedResult, encoder) => Task.FromResult<TagHelperContent>(
                     new DefaultTagHelperContent()));
 
-            var testTagHelperComponentManager = new TagHelperComponentManager(new []
+            var testTagHelperComponentManager = new TagHelperComponentManager(new[]
             {
                 new TestTagHelperComponent()
             });
@@ -282,6 +286,33 @@ namespace Microsoft.AspNetCore.Mvc.Razor.TagHelpers
             Assert.Equal($"Tag helper component '{typeof(TestTagHelperComponent)}' processed.", sink.Writes[0].State.ToString(), StringComparer.Ordinal);
         }
 
+        [Fact]
+        public void Init_GetsTagHelperComponentPropertyActivator_FromRequestServices()
+        {
+            // Arrange            
+            var tagHelperContext = new TagHelperContext(
+                "head",
+                allAttributes: new TagHelperAttributeList(
+                    Enumerable.Empty<TagHelperAttribute>()),
+                items: new Dictionary<object, object>(),
+                uniqueId: "test");
+
+            var testTagHelperComponentManager = new TagHelperComponentManager(new[]
+            {
+                new TestTagHelperComponent()
+            });
+
+            var testTagHelperComponentTagHelper = new TestTagHelperComponentTagHelper(
+                testTagHelperComponentManager,
+                NullLoggerFactory.Instance);
+
+            // Act
+            testTagHelperComponentTagHelper.Init(tagHelperContext);
+
+            // Assert
+            Assert.NotNull(testTagHelperComponentTagHelper.PropertyActivator);
+        }
+
         private class TestTagHelperComponentTagHelper : TagHelperComponentTagHelper
         {
             public TestTagHelperComponentTagHelper(
@@ -289,6 +320,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.TagHelpers
                 ILoggerFactory loggerFactory)
                 : base(manager, loggerFactory)
             {
+                ViewContext = CreateViewContext();
             }
         }
 
@@ -356,5 +388,18 @@ namespace Microsoft.AspNetCore.Mvc.Razor.TagHelpers
                 return Task.CompletedTask;
             }
         }
+
+        private static ViewContext CreateViewContext()
+        {
+            var httpContext = new DefaultHttpContext()
+            {
+                RequestServices = new ServiceCollection()
+                .AddSingleton<ITagHelperComponentPropertyActivator>(new TagHelperComponentPropertyActivator())
+                .BuildServiceProvider()
+            };
+
+            var viewContext = Mock.Of<ViewContext>(vc => vc.HttpContext == httpContext);
+            return viewContext;
+        }
     }
 }

test/WebSites/RazorWebSite/Controllers/AddTagHelperComponentController.cs

@@ -18,6 +18,7 @@ namespace RazorWebSite.Controllers
         public IActionResult AddComponent()
         {
             _tagHelperComponentManager.Components.Add(new TestBodyTagHelperComponent(0, "Processed TagHelperComponent added from controller."));
+            ViewData["TestData"] = "Value";
             return View("AddComponent");
         }
     }

test/WebSites/RazorWebSite/Services/TestBodyTagHelperComponent.cs

@@ -3,6 +3,8 @@
 
 using System;
 using System.Threading.Tasks;
+using Microsoft.AspNetCore.Mvc.Rendering;
+using Microsoft.AspNetCore.Mvc.ViewFeatures;
 using Microsoft.AspNetCore.Razor.TagHelpers;
 
 namespace RazorWebSite
@@ -23,6 +25,9 @@ namespace RazorWebSite
             _html = html;
         }
 
+        [ViewContext]
+        public ViewContext ViewContext { get; set; }
+
         public int Order => _order;
 
         public void Init(TagHelperContext context)
@@ -31,9 +36,11 @@ namespace RazorWebSite
 
         public Task ProcessAsync(TagHelperContext context, TagHelperOutput output)
         {
-            if (string.Equals(context.TagName, "body", StringComparison.Ordinal) && output.Attributes.ContainsName("inject"))
+            if (string.Equals(context.TagName, "body", StringComparison.Ordinal) &&
+                output.Attributes.ContainsName("inject"))
             {
                 output.PostContent.AppendHtml(_html);
+                ViewContext.ViewData["TestData"] = "NewValue";
             }
 
             return Task.FromResult(0);

test/WebSites/RazorWebSite/Views/TagHelperComponent/Body.cshtml

@@ -1,3 +1,4 @@
 <body inject="true">
 Hello from Body Tag Helper Component
+<p>@ViewData["TestData"]</p>
 </body>