Introduce ViewDataAttribute

Allow properties on controllers, Razor Page and Razor Page models annotatted with [ViewDataAttribute]
to populate ViewDataDictionary

Fixes https://github.com/aspnet/Mvc/issues/6525

build/dependencies.props

@@ -3,6 +3,7 @@
     <MSBuildAllProjects>$(MSBuildAllProjects);$(MSBuildThisFileFullPath)</MSBuildAllProjects>
   </PropertyGroup>
   <PropertyGroup Label="Package Versions">
+    <AngleSharpPackageVersion>0.9.9</AngleSharpPackageVersion>
     <BenchmarkDotNetPackageVersion>0.10.13</BenchmarkDotNetPackageVersion>
     <InternalAspNetCoreSdkPackageVersion>2.1.0-preview2-15749</InternalAspNetCoreSdkPackageVersion>
     <MicrosoftAspNetCoreAntiforgeryPackageVersion>2.1.0-preview2-30478</MicrosoftAspNetCoreAntiforgeryPackageVersion>

src/Microsoft.AspNetCore.Mvc.RazorPages/DependencyInjection/MvcRazorPagesMvcCoreBuilderExtensions.cs

@@ -101,6 +101,8 @@ namespace Microsoft.Extensions.DependencyInjection
                 ServiceDescriptor.Singleton<IPageApplicationModelProvider, AuthorizationPageApplicationModelProvider>());
             services.TryAddEnumerable(
                 ServiceDescriptor.Singleton<IPageApplicationModelProvider, TempDataFilterPageApplicationModelProvider>());
+            services.TryAddEnumerable(
+                ServiceDescriptor.Singleton<IPageApplicationModelProvider, ViewDataAttributePageApplicationModelProvider>());
             services.TryAddEnumerable(
                 ServiceDescriptor.Singleton<IPageApplicationModelProvider, ResponseCacheFilterApplicationModelProvider>());
 

src/Microsoft.AspNetCore.Mvc.RazorPages/Infrastructure/PageResultExecutor.cs

@@ -9,6 +9,7 @@ using Microsoft.AspNetCore.Mvc.Infrastructure;
 using Microsoft.AspNetCore.Mvc.Razor;
 using Microsoft.AspNetCore.Mvc.ViewEngines;
 using Microsoft.AspNetCore.Mvc.ViewFeatures;
+using Microsoft.AspNetCore.Mvc.ViewFeatures.Internal;
 
 namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
 {
@@ -66,6 +67,8 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
                 pageContext.ViewData.Model = result.Model;
             }
 
+            OnExecuting(pageContext);
+
             var viewStarts = new IRazorPage[pageContext.ViewStartFactories.Count];
             for (var i = 0; i < pageContext.ViewStartFactories.Count; i++)
             {
@@ -83,5 +86,14 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
 
             return ExecuteAsync(viewContext, result.ContentType, result.StatusCode);
         }
+
+        private void OnExecuting(PageContext pageContext)
+        {
+            var viewDataValuesProvider = pageContext.HttpContext.Features.Get<IViewDataValuesProviderFeature>();
+            if (viewDataValuesProvider != null)
+            {
+                viewDataValuesProvider.ProvideViewDataValues(pageContext.ViewData);
+            }
+        }
     }
 }

src/Microsoft.AspNetCore.Mvc.RazorPages/Internal/PageSaveTempDataPropertyFilterFactory.cs

@@ -4,7 +4,6 @@
 using System;
 using System.Collections.Generic;
 using Microsoft.AspNetCore.Mvc.Filters;
-using Microsoft.AspNetCore.Mvc.RazorPages.Internal;
 using Microsoft.AspNetCore.Mvc.ViewFeatures.Internal;
 using Microsoft.Extensions.DependencyInjection;
 

src/Microsoft.AspNetCore.Mvc.RazorPages/Internal/PageViewDataAttributeFilter.cs

@@ -0,0 +1,50 @@
+// 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.Mvc.Filters;
+using Microsoft.AspNetCore.Mvc.ViewFeatures;
+using Microsoft.AspNetCore.Mvc.ViewFeatures.Internal;
+
+namespace Microsoft.AspNetCore.Mvc.RazorPages
+{
+    internal class PageViewDataAttributeFilter : IPageFilter, IViewDataValuesProviderFeature
+    {
+        public PageViewDataAttributeFilter(IReadOnlyList<LifecycleProperty> properties)
+        {
+            Properties = properties;
+        }
+
+        public IReadOnlyList<LifecycleProperty> Properties { get;  }
+
+        public object Subject { get; set; }
+
+        public void OnPageHandlerExecuted(PageHandlerExecutedContext context)
+        {
+        }
+
+        public void OnPageHandlerExecuting(PageHandlerExecutingContext context)
+        {
+            Subject = context.HandlerInstance;
+            context.HttpContext.Features.Set<IViewDataValuesProviderFeature>(this);
+        }
+
+        public void OnPageHandlerSelected(PageHandlerSelectedContext context)
+        {
+        }
+
+        public void ProvideViewDataValues(ViewDataDictionary viewData)
+        {
+            for (var i = 0; i < Properties.Count; i++)
+            {
+                var property = Properties[i];
+                var value = property.GetValue(Subject);
+
+                if (value != null)
+                {
+                    viewData[property.Key] = value;
+                }
+            }
+        }
+    }
+}

src/Microsoft.AspNetCore.Mvc.RazorPages/Internal/PageViewDataAttributeFilterFactory.cs

@@ -0,0 +1,28 @@
+// 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.Filters;
+using Microsoft.AspNetCore.Mvc.ViewFeatures.Internal;
+
+namespace Microsoft.AspNetCore.Mvc.RazorPages
+{
+    internal class PageViewDataAttributeFilterFactory : IFilterFactory
+    {
+        public PageViewDataAttributeFilterFactory(IReadOnlyList<LifecycleProperty> properties)
+        {
+            Properties = properties;
+        }
+
+        public IReadOnlyList<LifecycleProperty> Properties { get; }
+
+        // PageViewDataAttributeFilter is stateful and cannot be reused.
+        public bool IsReusable => false;
+
+        public IFilterMetadata CreateInstance(IServiceProvider serviceProvider)
+        {
+            return new PageViewDataAttributeFilter(Properties);
+        }
+    }
+}

src/Microsoft.AspNetCore.Mvc.RazorPages/Internal/ViewDataAttributePageApplicationModelProvider.cs

@@ -0,0 +1,42 @@
+// 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 Microsoft.AspNetCore.Mvc.ApplicationModels;
+using Microsoft.AspNetCore.Mvc.RazorPages.Internal;
+using Microsoft.AspNetCore.Mvc.ViewFeatures.Internal;
+
+namespace Microsoft.AspNetCore.Mvc.RazorPages
+{
+    internal class ViewDataAttributePageApplicationModelProvider : IPageApplicationModelProvider
+    {
+        /// <inheritdoc />
+        /// <remarks>This order ensures that <see cref="ViewDataAttributePageApplicationModelProvider"/> runs after the <see cref="DefaultPageApplicationModelProvider"/>.</remarks>
+        public int Order => -1000 + 10;
+
+        /// <inheritdoc />
+        public void OnProvidersExecuted(PageApplicationModelProviderContext context)
+        {
+        }
+
+        /// <inheritdoc />
+        public void OnProvidersExecuting(PageApplicationModelProviderContext context)
+        {
+            if (context == null)
+            {
+                throw new ArgumentNullException(nameof(context));
+            }
+
+            var handlerType = context.PageApplicationModel.HandlerType.AsType();
+
+            var viewDataProperties = ViewDataAttributePropertyProvider.GetViewDataProperties(handlerType);
+            if (viewDataProperties == null)
+            {
+                return;
+            }
+
+            var filter = new PageViewDataAttributeFilterFactory(viewDataProperties);
+            context.PageApplicationModel.Filters.Add(filter);
+        }
+    }
+}

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

@@ -203,6 +203,8 @@ namespace Microsoft.Extensions.DependencyInjection
             //
             services.TryAddEnumerable(
                 ServiceDescriptor.Transient<IApplicationModelProvider, TempDataApplicationModelProvider>());
+            services.TryAddEnumerable(
+                ServiceDescriptor.Transient<IApplicationModelProvider, ViewDataAttributeApplicationModelProvider>());
             services.TryAddSingleton<SaveTempDataFilter>();
 
 

src/Microsoft.AspNetCore.Mvc.ViewFeatures/Internal/ControllerViewDataAttributeFilter.cs

@@ -0,0 +1,45 @@
+// 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.Mvc.Filters;
+using Microsoft.AspNetCore.Mvc.ViewFeatures.Internal;
+
+namespace Microsoft.AspNetCore.Mvc.ViewFeatures
+{
+    internal class ControllerViewDataAttributeFilter : IActionFilter, IViewDataValuesProviderFeature
+    {
+        public ControllerViewDataAttributeFilter(IReadOnlyList<LifecycleProperty> properties)
+        {
+            Properties = properties;
+        }
+
+        public object Subject { get; set; }
+
+        public IReadOnlyList<LifecycleProperty> Properties { get; }
+
+        public void OnActionExecuted(ActionExecutedContext context)
+        {
+        }
+
+        public void OnActionExecuting(ActionExecutingContext context)
+        {
+            Subject = context.Controller;
+            context.HttpContext.Features.Set<IViewDataValuesProviderFeature>(this);
+        }
+
+        public void ProvideViewDataValues(ViewDataDictionary viewData)
+        {
+            for (var i = 0; i < Properties.Count; i++)
+            {
+                var property = Properties[i];
+                var value = property.GetValue(Subject);
+
+                if (value != null)
+                {
+                    viewData[property.Key] = value;
+                }
+            }
+        }
+    }
+}

src/Microsoft.AspNetCore.Mvc.ViewFeatures/Internal/ControllerViewDataAttributeFilterFactory.cs

@@ -0,0 +1,28 @@
+// 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.Filters;
+using Microsoft.AspNetCore.Mvc.ViewFeatures.Internal;
+
+namespace Microsoft.AspNetCore.Mvc.ViewFeatures
+{
+    internal class ControllerViewDataAttributeFilterFactory : IFilterFactory
+    {
+        public ControllerViewDataAttributeFilterFactory(IReadOnlyList<LifecycleProperty> properties)
+        {
+            Properties = properties;
+        }
+
+        public IReadOnlyList<LifecycleProperty> Properties { get; }
+
+        // ControllerViewDataAttributeFilter is stateful and cannot be reused.
+        public bool IsReusable => false;
+
+        public IFilterMetadata CreateInstance(IServiceProvider serviceProvider)
+        {
+            return new ControllerViewDataAttributeFilter(Properties);
+        }
+    }
+}

src/Microsoft.AspNetCore.Mvc.ViewFeatures/Internal/IViewDataValuesProviderFeature.cs

@@ -0,0 +1,10 @@
+// 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.
+
+namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Internal
+{
+    public interface IViewDataValuesProviderFeature
+    {
+        void ProvideViewDataValues(ViewDataDictionary viewData);
+    }
+}

src/Microsoft.AspNetCore.Mvc.ViewFeatures/Internal/ViewDataAttributeApplicationModelProvider.cs

@@ -0,0 +1,45 @@
+// 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 Microsoft.AspNetCore.Mvc.ApplicationModels;
+using Microsoft.AspNetCore.Mvc.Internal;
+using Microsoft.AspNetCore.Mvc.ViewFeatures.Internal;
+
+namespace Microsoft.AspNetCore.Mvc.ViewFeatures
+{
+    internal class ViewDataAttributeApplicationModelProvider : IApplicationModelProvider
+    {
+        /// <inheritdoc />
+        /// <remarks>This order ensures that <see cref="ViewDataAttributeApplicationModelProvider"/> runs after the <see cref="DefaultApplicationModelProvider"/>.</remarks>
+        public int Order => -1000 + 10;
+
+        /// <inheritdoc />
+        public void OnProvidersExecuted(ApplicationModelProviderContext context)
+        {
+        }
+
+        /// <inheritdoc />
+        public void OnProvidersExecuting(ApplicationModelProviderContext context)
+        {
+            if (context == null)
+            {
+                throw new ArgumentNullException(nameof(context));
+            }
+
+            foreach (var controllerModel in context.Result.Controllers)
+            {
+                var controllerType = controllerModel.ControllerType.AsType();
+
+                var viewDataProperties = ViewDataAttributePropertyProvider.GetViewDataProperties(controllerType);
+                if (viewDataProperties == null)
+                {
+                    continue;
+                }
+
+                var filter = new ControllerViewDataAttributeFilterFactory(viewDataProperties);
+                controllerModel.Filters.Add(filter);
+            }
+        }
+    }
+}

src/Microsoft.AspNetCore.Mvc.ViewFeatures/Internal/ViewDataAttributePropertyProvider.cs

@@ -0,0 +1,44 @@
+// 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 System.Reflection;
+using Microsoft.Extensions.Internal;
+
+namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Internal
+{
+    public static class ViewDataAttributePropertyProvider
+    {
+        public static IReadOnlyList<LifecycleProperty> GetViewDataProperties(Type type)
+        {
+            List<LifecycleProperty> results = null;
+
+            var propertyHelpers = PropertyHelper.GetVisibleProperties(type: type);
+
+            for (var i = 0; i < propertyHelpers.Length; i++)
+            {
+                var propertyHelper = propertyHelpers[i];
+                var property = propertyHelper.Property;
+                var tempDataAttribute = property.GetCustomAttribute<ViewDataAttribute>();
+                if (tempDataAttribute != null)
+                {
+                    if (results == null)
+                    {
+                        results = new List<LifecycleProperty>();
+                    }
+
+                    var key = tempDataAttribute.Key;
+                    if (string.IsNullOrEmpty(key))
+                    {
+                        key = property.Name;
+                    }
+
+                    results.Add(new LifecycleProperty(property, key));
+                }
+            }
+
+            return results;
+        }
+    }
+}

src/Microsoft.AspNetCore.Mvc.ViewFeatures/ViewDataAttribute.cs

@@ -0,0 +1,25 @@
+// 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.ViewFeatures;
+using Microsoft.AspNetCore.Mvc.ViewFeatures.Internal;
+
+namespace Microsoft.AspNetCore.Mvc
+{
+    /// <summary>
+    /// Properties decorated with <see cref="ViewDataAttribute"/> will have their values stored in
+    /// and loaded from the <see cref="ViewDataDictionary"/>. <see cref="ViewDataDictionary"/>
+    /// is supported on properties of Controllers, and Razor Page handlers.
+    /// </summary>
+    [AttributeUsage(AttributeTargets.Property, Inherited = true, AllowMultiple = false)]
+    public sealed class ViewDataAttribute : Attribute
+    {
+        /// <summary>
+        /// Gets or sets the key used to get or add the property from value from <see cref="ViewDataDictionary"/>.
+        /// When unspecified, the key is the property name.
+        /// </summary>
+        public string Key { get; set; }
+    }
+}

src/Microsoft.AspNetCore.Mvc.ViewFeatures/ViewFeatures/ViewComponentResultExecutor.cs

@@ -115,6 +115,8 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures
                     writer,
                     _htmlHelperOptions);
 
+                OnExecuting(viewContext);
+
                 // IViewComponentHelper is stateful, we want to make sure to retrieve it every time we need it.
                 var viewComponentHelper = context.HttpContext.RequestServices.GetRequiredService<IViewComponentHelper>();
                 (viewComponentHelper as IViewContextAware)?.Contextualize(viewContext);
@@ -124,6 +126,15 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures
             }
         }
 
+        private void OnExecuting(ViewContext viewContext)
+        {
+            var viewDataValuesProvider = viewContext.HttpContext.Features.Get<IViewDataValuesProviderFeature>();
+            if (viewDataValuesProvider != null)
+            {
+                viewDataValuesProvider.ProvideViewDataValues(viewContext.ViewData);
+            }
+        }
+
         private Task<IHtmlContent> GetViewComponentResult(IViewComponentHelper viewComponentHelper, ILogger logger, ViewComponentResult result)
         {
             if (result.ViewComponentType == null && result.ViewComponentName == null)

src/Microsoft.AspNetCore.Mvc.ViewFeatures/ViewFeatures/ViewExecutor.cs

@@ -231,6 +231,8 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures
                 response.StatusCode = statusCode.Value;
             }
 
+            OnExecuting(viewContext);
+
             using (var writer = WriterFactory.CreateWriter(response.Body, resolvedContentTypeEncoding))
             {
                 var view = viewContext.View;
@@ -257,5 +259,14 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures
                 await writer.FlushAsync();
             }
         }
+
+        private void OnExecuting(ViewContext viewContext)
+        {
+            var viewDataValuesProvider = viewContext.HttpContext.Features.Get<IViewDataValuesProviderFeature>();
+            if (viewDataValuesProvider != null)
+            {
+                viewDataValuesProvider.ProvideViewDataValues(viewContext.ViewData);
+            }
+        }
     }
 }

src/Microsoft.AspNetCore.Mvc.ViewFeatures/ViewFeatures/ViewResultExecutor.cs

@@ -167,7 +167,6 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures
             var view = viewEngineResult.View;
             using (view as IDisposable)
             {
-
                 await ExecuteAsync(
                     context,
                     view,

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

@@ -489,5 +489,36 @@ namespace Microsoft.AspNetCore.Mvc.FunctionalTests
             // Assert
             Assert.Equal(expected, assemblyParts);
         }
+
+        [Fact]
+        public async Task ViewDataProperties_AreTransferredToViews()
+        {
+            // Act
+            var document = await Client.GetHtmlDocumentAsync("ViewDataProperty/ViewDataPropertyToView");
+
+            // Assert
+            var message = document.QuerySelector("#message").TextContent;
+            Assert.Equal("Message set in action", message);
+
+            var filterMessage = document.QuerySelector("#filter-message").TextContent;
+            Assert.Equal("Value set in OnActionExecuting", filterMessage);
+
+            var title = document.QuerySelector("title").TextContent;
+            Assert.Equal("View Data Property Sample", title);
+        }
+
+        [Fact]
+        public async Task ViewDataProperties_AreTransferredToViewComponents()
+        {
+            // Act
+            var document = await Client.GetHtmlDocumentAsync("ViewDataProperty/ViewDataPropertyToViewComponent");
+
+            // Assert
+            var message = document.QuerySelector("#message").TextContent;
+            Assert.Equal("Message set in action", message);
+
+            var title = document.QuerySelector("title").TextContent;
+            Assert.Equal("View Data Property Sample", title);
+        }
     }
 }

test/Microsoft.AspNetCore.Mvc.FunctionalTests/Infrastructure/HttpClientExtensions.cs

@@ -0,0 +1,75 @@
+// 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.Net;
+using System.Net.Http;
+using System.Threading.Tasks;
+using AngleSharp.Dom.Html;
+using AngleSharp.Parser.Html;
+using Xunit;
+using Xunit.Sdk;
+
+namespace Microsoft.AspNetCore.Mvc.FunctionalTests
+{
+    public static class HttpClientExtensions
+    {
+        public static async Task<IHtmlDocument> GetHtmlDocumentAsync(this HttpClient client, string requestUri)
+        {
+            var response = await client.GetAsync(requestUri);
+            await AssertStatusCodeAsync(response, HttpStatusCode.OK);
+
+            var content = await response.Content.ReadAsStringAsync();
+            var parser = new HtmlParser();
+            var document = parser.Parse(content);
+            if (document == null)
+            {
+                throw new InvalidOperationException("Response content could not be parsed as HTML: " + Environment.NewLine + content);
+            }
+
+            return document;
+        }
+
+        public static async Task<HttpResponseMessage> AssertStatusCodeAsync(this HttpResponseMessage response, HttpStatusCode expectedStatusCode)
+        {
+            if (response.StatusCode == HttpStatusCode.OK)
+            {
+                return response;
+            }
+
+            string responseContent = null;
+            try
+            {
+                responseContent = await response.Content.ReadAsStringAsync();
+            }
+            catch
+            {
+                // No-op
+            }
+
+            throw new StatusCodeMismatchException
+            {
+                ExpectedStatusCode = HttpStatusCode.OK,
+                ActualStatusCode = response.StatusCode,
+                ResponseContent = responseContent,
+            };
+        }
+
+        private class StatusCodeMismatchException : XunitException
+        {
+            public HttpStatusCode ExpectedStatusCode { get; set; }
+
+            public HttpStatusCode ActualStatusCode { get; set; }
+
+            public string ResponseContent { get; set; }
+
+            public override string Message
+            {
+                get
+                {
+                    return $"Excepted status code 200. Actual {ActualStatusCode}. Response Content:" + Environment.NewLine + ResponseContent;
+                }
+            }
+        }
+    }
+}

test/Microsoft.AspNetCore.Mvc.FunctionalTests/Microsoft.AspNetCore.Mvc.FunctionalTests.csproj

@@ -18,20 +18,10 @@
 
   <ItemGroup>
     <!-- For testing the testing infrastructure only -->
-    <WebApplicationFactoryContentRootAttribute
-      Include="BasicWebSite"
-      AssemblyName="BasicWebsite"
-      ContentRootPath="../../../../WebSites/BasicWebSite"
-      ContentRootTest="BasicWebSite.csproj"
-      Priority="-1" />
+    <WebApplicationFactoryContentRootAttribute Include="BasicWebSite" AssemblyName="BasicWebsite" ContentRootPath="../../../../WebSites/BasicWebSite" ContentRootTest="BasicWebSite.csproj" Priority="-1" />
     <!-- For testing the testing infrastructure only. This attribute is
      incorrect by design to ensure that the infrastructure falls back. -->
-    <WebApplicationFactoryContentRootAttribute
-      Include="FiltersWebSite"
-      AssemblyName="FiltersWebSite"
-      ContentRootPath="/../WebSites/FiltersWebSite"
-      ContentRootTest="Incorrect.csproj"
-      Priority="-1" />
+    <WebApplicationFactoryContentRootAttribute Include="FiltersWebSite" AssemblyName="FiltersWebSite" ContentRootPath="/../WebSites/FiltersWebSite" ContentRootTest="Incorrect.csproj" Priority="-1" />
   </ItemGroup>
 
   <ItemGroup>
@@ -59,6 +49,7 @@
     <ProjectReference Include="..\WebSites\WebApiCompatShimWebSite\WebApiCompatShimWebSite.csproj" />
     <ProjectReference Include="..\WebSites\XmlFormattersWebSite\XmlFormattersWebSite.csproj" />
 
+    <PackageReference Include="AngleSharp" Version="$(AngleSharpPackageVersion)" />
     <PackageReference Include="Microsoft.AspNetCore.ChunkingCookieManager.Sources" PrivateAssets="All" Version="$(MicrosoftAspNetCoreChunkingCookieManagerSourcesPackageVersion)" />
     <PackageReference Include="Microsoft.AspNetCore.Http" Version="$(MicrosoftAspNetCoreHttpPackageVersion)" />
     <PackageReference Include="Microsoft.AspNetCore.TestHost" Version="$(MicrosoftAspNetCoreTestHostPackageVersion)" />

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

@@ -845,7 +845,6 @@ Microsoft.AspNetCore.Mvc.ViewFeatures.ViewDataDictionary`1[AspNetCore.InjectedPa
             Assert.Equal(expected, response.Headers.Location.ToString());
         }
 
-
         [Fact]
         public async Task RedirectToSelfWorks()
         {

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

@@ -504,5 +504,53 @@ Hello from /Pages/Shared/";
             // Assert
             Assert.Contains("This page is overriden by RazorPagesWebSite", response);
         }
+
+        [Fact]
+        public async Task ViewDataAttributes_SetInPageModel_AreTransferedToLayout()
+        {
+            // Arrange
+            var document = await Client.GetHtmlDocumentAsync("/ViewData/ViewDataInPage");
+
+            // Assert
+            var description = document.QuerySelector("meta[name='description']").Attributes["content"];
+            Assert.Equal("Description set in handler", description.Value);
+
+            var keywords = document.QuerySelector("meta[name='keywords']").Attributes["content"];
+            Assert.Equal("Value set in filter", keywords.Value);
+
+            var author = document.QuerySelector("meta[name='author']").Attributes["content"];
+            Assert.Equal("Property with key", author.Value);
+
+            var title = document.QuerySelector("title").TextContent;
+            Assert.Equal("Title with default value", title);
+        }
+
+        [Fact]
+        public async Task ViewDataAttributes_SetInPageWithoutModel_AreTransferedToLayout()
+        {
+            // Arrange
+            var document = await Client.GetHtmlDocumentAsync("/ViewData/ViewDataInPageWithoutModel");
+
+            // Assert
+            var description = document.QuerySelector("meta[name='description']").Attributes["content"];
+            Assert.Equal("Description set in page handler", description.Value);
+
+            var title = document.QuerySelector("title").TextContent;
+            Assert.Equal("Default value", title);
+        }
+
+        [Fact]
+        public async Task ViewDataProperties_SetInPageModel_AreTransferredToViewComponents()
+        {
+            // Act
+            var document = await Client.GetHtmlDocumentAsync("ViewData/ViewDataToViewComponentPage");
+
+            // Assert
+            var message = document.QuerySelector("#message").TextContent;
+            Assert.Equal("Message set in handler", message);
+
+            var title = document.QuerySelector("title").TextContent;
+            Assert.Equal("View Data in Pages", title);
+        }
     }
 }

test/Microsoft.AspNetCore.Mvc.RazorPages.Test/Internal/PageViewDataAttributeFilterFactoryTest.cs

@@ -0,0 +1,32 @@
+// 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 Microsoft.AspNetCore.Mvc.ViewFeatures.Internal;
+using Moq;
+using Xunit;
+
+namespace Microsoft.AspNetCore.Mvc.RazorPages
+{
+    public class PageViewDataAttributeFilterFactoryTest
+    {
+        [Fact]
+        public void CreateInstance_CreatesFilter()
+        {
+            // Arrange
+            var properties = new LifecycleProperty[]
+            {
+                new LifecycleProperty(),
+                new LifecycleProperty(),
+            };
+            var filterFactory = new PageViewDataAttributeFilterFactory(properties);
+
+            // Act
+            var result = filterFactory.CreateInstance(Mock.Of<IServiceProvider>());
+
+            // Assert
+            var filter = Assert.IsType<PageViewDataAttributeFilter>(result);
+            Assert.Same(properties, filter.Properties);
+        }
+    }
+}

test/Microsoft.AspNetCore.Mvc.RazorPages.Test/Internal/PageViewDataAttributeFilterTest.cs

@@ -0,0 +1,105 @@
+// 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 System.Linq;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Mvc.Abstractions;
+using Microsoft.AspNetCore.Mvc.Filters;
+using Microsoft.AspNetCore.Mvc.ModelBinding;
+using Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure;
+using Microsoft.AspNetCore.Mvc.ViewFeatures;
+using Microsoft.AspNetCore.Mvc.ViewFeatures.Internal;
+using Microsoft.AspNetCore.Routing;
+using Xunit;
+
+namespace Microsoft.AspNetCore.Mvc.RazorPages
+{
+    public class PageViewDataAttributeFilterTest
+    {
+        [Fact]
+        public void OnPageHandlerExecuting_AddsFeature()
+        {
+            // Arrange
+            var filter = new PageViewDataAttributeFilter(Array.Empty<LifecycleProperty>());
+            var handler = new object();
+            var httpContext = new DefaultHttpContext();
+            var actionContext = new ActionContext(httpContext, new RouteData(), new ActionDescriptor());
+            var pageContext = new PageContext(actionContext);
+            var context = new PageHandlerExecutingContext(pageContext, new IFilterMetadata[0], new HandlerMethodDescriptor(), new Dictionary<string, object>(), handler);
+
+            // Act
+            filter.OnPageHandlerExecuting(context);
+
+            // Assert
+            var feature = Assert.Single(httpContext.Features, f => f.Key == typeof(IViewDataValuesProviderFeature));
+            Assert.Same(filter, feature.Value);
+        }
+
+        [Fact]
+        public void OnPageHandlerExecuting_SetsSubject()
+        {
+            // Arrange
+            var filter = new PageViewDataAttributeFilter(Array.Empty<LifecycleProperty>());
+            var handler = new object();
+            var httpContext = new DefaultHttpContext();
+            var actionContext = new ActionContext(httpContext, new RouteData(), new ActionDescriptor());
+            var pageContext = new PageContext(actionContext);
+            var context = new PageHandlerExecutingContext(pageContext, new IFilterMetadata[0], new HandlerMethodDescriptor(), new Dictionary<string, object>(), handler);
+
+            // Act
+            filter.OnPageHandlerExecuting(context);
+
+            // Assert
+            Assert.Same(handler, filter.Subject);
+        }
+
+        [Fact]
+        public void ProvideValues_AddsNonNullPropertyValuesToViewData()
+        {
+            // Arrange
+            var type = typeof(TestModel);
+            var properties = new[]
+            {
+                new LifecycleProperty(type.GetProperty(nameof(TestModel.Prop1)), "Prop1"),
+                new LifecycleProperty(type.GetProperty(nameof(TestModel.Prop2)), "Prop2"),
+                new LifecycleProperty(type.GetProperty(nameof(TestModel.Prop3)), "Prop3"),
+            };
+
+            var controller = new TestModel();
+            var filter = new PageViewDataAttributeFilter(properties)
+            {
+                Subject = controller,
+            };
+            var viewData = new ViewDataDictionary(new EmptyModelMetadataProvider(), new ModelStateDictionary());
+
+            // Act
+            controller.Prop1 = "New-Value";
+            filter.ProvideViewDataValues(viewData);
+
+            // Assert
+            Assert.Collection(
+                viewData.OrderBy(kvp => kvp.Key),
+                kvp =>
+                {
+                    Assert.Equal("Prop1", kvp.Key);
+                    Assert.Equal("New-Value", kvp.Value);
+                },
+                kvp =>
+                {
+                    Assert.Equal("Prop2", kvp.Key);
+                    Assert.Equal("Test", kvp.Value);
+                });
+        }
+
+        public class TestModel
+        {
+            public string Prop1 { get; set; }
+
+            public string Prop2 => "Test";
+
+            public string Prop3 { get; set; }
+        }
+    }
+}

test/Microsoft.AspNetCore.Mvc.RazorPages.Test/Internal/ViewDataAttributePageApplicationModelProviderTest.cs

@@ -0,0 +1,77 @@
+// 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.Reflection;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Mvc.ApplicationModels;
+using Xunit;
+
+namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
+{
+    public class ViewDataAttributePageApplicationModelProviderTest
+    {
+        [Fact]
+        public void OnProvidersExecuting_DoesNotAddFilter_IfTypeHasNoViewDataProperties()
+        {
+            // Arrange
+            var type = typeof(TestPageModel_NoViewDataProperties);
+            var provider = new ViewDataAttributePageApplicationModelProvider();
+            var context = CreateProviderContext(type);
+
+            // Act
+            provider.OnProvidersExecuting(context);
+
+            // Assert
+            Assert.Empty(context.PageApplicationModel.Filters);
+        }
+
+        [Fact]
+        public void AddsViewDataPropertyFilter_ForViewDataAttributeProperties()
+        {
+            // Arrange
+            var type = typeof(TestPageModel_ViewDataProperties);
+            var provider = new ViewDataAttributePageApplicationModelProvider();
+            var context = CreateProviderContext(type);
+
+            // Act
+            provider.OnProvidersExecuting(context);
+
+            // Assert
+            var filter = Assert.Single(context.PageApplicationModel.Filters);
+            var viewDataFilter = Assert.IsType<PageViewDataAttributeFilterFactory>(filter);
+            Assert.Collection(
+                viewDataFilter.Properties,
+                property => Assert.Equal(nameof(TestPageModel_ViewDataProperties.DateTime), property.PropertyInfo.Name));
+        }
+
+        private static PageApplicationModelProviderContext CreateProviderContext(Type handlerType)
+        {
+            var descriptor = new CompiledPageActionDescriptor();
+            var context = new PageApplicationModelProviderContext(descriptor, typeof(TestPage).GetTypeInfo())
+            {
+                PageApplicationModel = new PageApplicationModel(descriptor, handlerType.GetTypeInfo(), Array.Empty<object>()),
+            };
+
+            return context;
+        }
+
+        private class TestPage : Page
+        {
+            public object Model => null;
+
+            public override Task ExecuteAsync() => null;
+        }
+
+        public class TestPageModel_NoViewDataProperties
+        {
+            public DateTime? DateTime { get; set; }
+        }
+
+        public class TestPageModel_ViewDataProperties
+        {
+            [ViewData]
+            public DateTime? DateTime { get; set; }
+        }
+    }
+}

test/Microsoft.AspNetCore.Mvc.Test/MvcServiceCollectionExtensionsTest.cs

@@ -442,6 +442,7 @@ namespace Microsoft.AspNetCore.Mvc
                             typeof(CorsApplicationModelProvider),
                             typeof(AuthorizationApplicationModelProvider),
                             typeof(TempDataApplicationModelProvider),
+                            typeof(ViewDataAttributeApplicationModelProvider),
                             typeof(ApiBehaviorApplicationModelProvider),
                         }
                     },
@@ -469,6 +470,7 @@ namespace Microsoft.AspNetCore.Mvc
                             typeof(AuthorizationPageApplicationModelProvider),
                             typeof(DefaultPageApplicationModelProvider),
                             typeof(TempDataFilterPageApplicationModelProvider),
+                            typeof(ViewDataAttributePageApplicationModelProvider),
                             typeof(ResponseCacheFilterApplicationModelProvider),
                         }
                     },

test/Microsoft.AspNetCore.Mvc.ViewFeatures.Test/Internal/ControllerViewDataAttributeFilterFactoryTest.cs

@@ -0,0 +1,32 @@
+// 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 Microsoft.AspNetCore.Mvc.ViewFeatures.Internal;
+using Moq;
+using Xunit;
+
+namespace Microsoft.AspNetCore.Mvc.ViewFeatures
+{
+    public class ControllerViewDataAttributeFilterFactoryTest
+    {
+        [Fact]
+        public void CreateInstance_CreatesFilter()
+        {
+            // Arrange
+            var properties = new LifecycleProperty[]
+            {
+                new LifecycleProperty(),
+                new LifecycleProperty(),
+            };
+            var filterFactory = new ControllerViewDataAttributeFilterFactory(properties);
+
+            // Act
+            var result = filterFactory.CreateInstance(Mock.Of<IServiceProvider>());
+
+            // Assert
+            var filter = Assert.IsType<ControllerViewDataAttributeFilter>(result);
+            Assert.Same(properties, filter.Properties);
+        }
+    }
+}

test/Microsoft.AspNetCore.Mvc.ViewFeatures.Test/Internal/ControllerViewDataAttributeFilterTest.cs

@@ -0,0 +1,101 @@
+// 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 System.Linq;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Mvc.Abstractions;
+using Microsoft.AspNetCore.Mvc.Filters;
+using Microsoft.AspNetCore.Mvc.ModelBinding;
+using Microsoft.AspNetCore.Mvc.ViewFeatures.Internal;
+using Microsoft.AspNetCore.Routing;
+using Xunit;
+
+namespace Microsoft.AspNetCore.Mvc.ViewFeatures
+{
+    public class ControllerViewDataAttributeFilterTest
+    {
+        [Fact]
+        public void OnActionExecuting_AddsFeature()
+        {
+            // Arrange
+            var filter = new ControllerViewDataAttributeFilter(Array.Empty<LifecycleProperty>());
+            var controller = new object();
+            var httpContext = new DefaultHttpContext();
+            var actionContext = new ActionContext(httpContext, new RouteData(), new ActionDescriptor());
+            var context = new ActionExecutingContext(actionContext, new IFilterMetadata[0], new Dictionary<string, object>(), controller);
+
+            // Act
+            filter.OnActionExecuting(context);
+
+            // Assert
+            var feature = Assert.Single(httpContext.Features, f => f.Key == typeof(IViewDataValuesProviderFeature));
+            Assert.Same(filter, feature.Value);
+        }
+
+        [Fact]
+        public void OnActionExecuting_SetsSubject()
+        {
+            // Arrange
+            var filter = new ControllerViewDataAttributeFilter(Array.Empty<LifecycleProperty>());
+            var controller = new object();
+            var httpContext = new DefaultHttpContext();
+            var actionContext = new ActionContext(httpContext, new RouteData(), new ActionDescriptor());
+            var context = new ActionExecutingContext(actionContext, new IFilterMetadata[0], new Dictionary<string, object>(), controller);
+
+            // Act
+            filter.OnActionExecuting(context);
+
+            // Assert
+            Assert.Same(controller, filter.Subject);
+        }
+
+        [Fact]
+        public void ProvideValues_AddsNonNullPropertyValuesToViewData()
+        {
+            // Arrange
+            var type = typeof(TestController);
+            var properties = new[]
+            {
+                new LifecycleProperty(type.GetProperty(nameof(TestController.Prop1)), "Prop1"),
+                new LifecycleProperty(type.GetProperty(nameof(TestController.Prop2)), "Prop2"),
+                new LifecycleProperty(type.GetProperty(nameof(TestController.Prop3)), "Prop3"),
+            };
+
+            var controller = new TestController();
+            var filter = new ControllerViewDataAttributeFilter(properties)
+            {
+                Subject = controller,
+            };
+            var viewData = new ViewDataDictionary(new EmptyModelMetadataProvider(), new ModelStateDictionary());
+
+            // Act
+            controller.Prop1 = "New-Value";
+            filter.ProvideViewDataValues(viewData);
+
+            // Assert
+            Assert.Collection(
+                viewData.OrderBy(kvp => kvp.Key),
+                kvp =>
+                {
+                    Assert.Equal("Prop1", kvp.Key);
+                    Assert.Equal("New-Value", kvp.Value);
+                },
+                kvp =>
+                {
+                    Assert.Equal("Prop2", kvp.Key);
+                    Assert.Equal("Test", kvp.Value);
+                });
+        }
+
+        public class TestController
+        {
+            public string Prop1 { get; set; }
+
+            public string Prop2 => "Test";
+
+            public string Prop3 { get; set; }
+        }
+    }
+}

test/Microsoft.AspNetCore.Mvc.ViewFeatures.Test/Internal/ViewDataAttributeApplicationModelProviderTest.cs

@@ -0,0 +1,99 @@
+// 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.Linq;
+using System.Reflection;
+using Microsoft.AspNetCore.Mvc.ApplicationModels;
+using Microsoft.AspNetCore.Mvc.Internal;
+using Microsoft.AspNetCore.Mvc.ModelBinding;
+using Microsoft.Extensions.Options;
+using Xunit;
+
+namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Internal
+{
+    public class ViewDataAttributeApplicationModelProviderTest
+    {
+        [Fact]
+        public void OnProvidersExecuting_DoesNotAddFilter_IfTypeHasNoViewDataProperties()
+        {
+            // Arrange
+            var type = typeof(TestController_NoViewDataProperties);
+            var provider = new ViewDataAttributeApplicationModelProvider();
+            var context = GetContext(type);
+
+            // Act
+            provider.OnProvidersExecuting(context);
+
+            // Assert
+            var controller = Assert.Single(context.Result.Controllers);
+            Assert.Empty(controller.Filters);
+        }
+
+        [Fact]
+        public void AddsViewDataPropertyFilter_ForViewDataAttributeProperties()
+        {
+            // Arrange
+            var type = typeof(TestController_NullableNonPrimitiveViewDataProperty);
+            var provider = new ViewDataAttributeApplicationModelProvider();
+            var context = GetContext(type);
+
+            // Act
+            provider.OnProvidersExecuting(context);
+
+            // Assert
+            var controller = Assert.Single(context.Result.Controllers);
+            Assert.IsType<ControllerViewDataAttributeFilterFactory>(Assert.Single(controller.Filters));
+        }
+
+        [Fact]
+        public void InitializeFilterFactory_WithExpectedPropertyHelpers_ForViewDataAttributeProperties()
+        {
+            // Arrange
+            var expected = typeof(TestController_OneViewDataProperty).GetProperty(nameof(TestController_OneViewDataProperty.Test2));
+            var provider = new ViewDataAttributeApplicationModelProvider();
+            var context = GetContext(typeof(TestController_OneViewDataProperty));
+
+            // Act
+            provider.OnProvidersExecuting(context);
+            var controller = context.Result.Controllers.SingleOrDefault();
+            var filter = Assert.IsType<ControllerViewDataAttributeFilterFactory>(Assert.Single(controller.Filters));
+
+            // Assert
+            Assert.NotNull(filter);
+            var property = Assert.Single(filter.Properties);
+            Assert.Same(expected, property.PropertyInfo);
+            Assert.Equal("Test2", property.Key);
+        }
+
+        private static ApplicationModelProviderContext GetContext(Type type)
+        {
+            var defaultProvider = new DefaultApplicationModelProvider(
+                Options.Create(new MvcOptions()),
+                new EmptyModelMetadataProvider());
+
+            var context = new ApplicationModelProviderContext(new[] { type.GetTypeInfo() });
+            defaultProvider.OnProvidersExecuting(context);
+            return context;
+        }
+
+        public class TestController_NoViewDataProperties
+        {
+            public DateTime? DateTime { get; set; }
+        }
+
+        public class TestController_NullableNonPrimitiveViewDataProperty
+        {
+            [ViewData]
+            public DateTime? DateTime { get; set; }
+        }
+
+        public class TestController_OneViewDataProperty
+        {
+            public string Test { get; set; }
+
+            [ViewData]
+            public string Test2 { get; set; }
+        }
+    }
+}

test/Microsoft.AspNetCore.Mvc.ViewFeatures.Test/Internal/ViewDataAttributePropertyProviderTest.cs

@@ -0,0 +1,102 @@
+// 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.Linq;
+using Xunit;
+
+namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Internal
+{
+    public class ViewDataAttributePropertyProviderTest
+    {
+        [Fact]
+        public void GetViewDataProperties_ReturnsNull_IfTypeDoesNotHaveAnyViewDataProperties()
+        {
+            // Arrange
+            var type = typeof(TestController_NoViewDataProperties);
+
+            // Act
+            var result = ViewDataAttributePropertyProvider.GetViewDataProperties(type);
+
+            // Assert
+            Assert.Null(result);
+        }
+
+        [Fact]
+        public void GetViewDataProperties_ReturnsViewDataProperties()
+        {
+            // Arrange
+            var type = typeof(BaseController);
+
+            // Act
+            var result = ViewDataAttributePropertyProvider.GetViewDataProperties(type);
+
+            // Assert
+            Assert.Collection(
+                result.OrderBy(p => p.Key),
+                property =>
+                {
+                    Assert.Equal(nameof(BaseController.BaseProperty), property.PropertyInfo.Name);
+                    Assert.Equal(nameof(BaseController.BaseProperty), property.Key);
+                });
+        }
+
+        [Fact]
+        public void GetViewDataProperties_ReturnsViewDataProperties_FromBaseTypes()
+        {
+            // Arrange
+            var type = typeof(DerivedController);
+
+            // Act
+            var result = ViewDataAttributePropertyProvider.GetViewDataProperties(type);
+
+            // Assert
+            Assert.Collection(
+                result.OrderBy(p => p.Key),
+                property => Assert.Equal(nameof(BaseController.BaseProperty), property.PropertyInfo.Name),
+                property => Assert.Equal(nameof(DerivedController.DeriviedProperty), property.PropertyInfo.Name));
+        }
+
+        [Fact]
+        public void GetViewDataProperties_UsesKeyFromViewDataAttribute()
+        {
+            // Arrange
+            var type = typeof(PropertyWithKeyController);
+
+            // Act
+            var result = ViewDataAttributePropertyProvider.GetViewDataProperties(type);
+
+            // Assert
+            Assert.Collection(
+                result.OrderBy(p => p.Key),
+                property =>
+                {
+                    Assert.Equal(nameof(PropertyWithKeyController.Different), property.PropertyInfo.Name);
+                    Assert.Equal("Test", property.Key);
+                });
+        }
+
+        public class TestController_NoViewDataProperties
+        {
+            public DateTime? DateTime { get; set; }
+        }
+
+        public class BaseController
+        {
+            [ViewData]
+            public string BaseProperty { get; }
+        }
+
+        public class DerivedController : BaseController
+        {
+            [ViewData]
+            public string DeriviedProperty { get; set; }
+        }
+
+        public class PropertyWithKeyController
+        {
+            [ViewData(Key = "Test")]
+            public string Different { get; set; }
+        }
+    }
+}

test/WebSites/BasicWebSite/Components/PassThroughViewComponent.cs

@@ -3,7 +3,7 @@
 
 using Microsoft.AspNetCore.Mvc;
 
-namespace HtmlGenerationWebSite.Components
+namespace BasicWebSite.Components
 {
     public class PassThroughViewComponent : ViewComponent
     {

test/WebSites/BasicWebSite/Components/ViewDataViewComponent.cs

@@ -0,0 +1,12 @@
+// 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;
+
+namespace BasicWebSite.Components
+{
+    public class ViewDataViewComponent : ViewComponent
+    {
+        public IViewComponentResult Invoke() => View();
+    }
+}

test/WebSites/BasicWebSite/Controllers/PassThroughController.cs

@@ -1,7 +1,7 @@
 // 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 HtmlGenerationWebSite.Components;
+using BasicWebSite.Components;
 using Microsoft.AspNetCore.Mvc;
 
 namespace BasicWebSite.Controllers

test/WebSites/BasicWebSite/Controllers/ViewDataPropertyController.cs

@@ -0,0 +1,40 @@
+// 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 BasicWebSite.Components;
+using BasicWebSite.Models;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Mvc.Filters;
+using Microsoft.AspNetCore.Mvc.ViewFeatures;
+
+namespace BasicWebSite.Controllers
+{
+    public class ViewDataPropertyController : Controller
+    {
+        [ViewData]
+        public string Title => "View Data Property Sample";
+
+        [ViewData]
+        public string Message { get; private set; }
+
+        [ViewData]
+        public string FilterMessage { get; set; }
+
+        public IActionResult ViewDataPropertyToView()
+        {
+            Message = "Message set in action";
+            return View();
+        }
+
+        public IActionResult ViewDataPropertyToViewComponent()
+        {
+            Message = "Message set in action";
+            return ViewComponent(typeof(ViewDataViewComponent));
+        }
+
+        public override void OnActionExecuting(ActionExecutingContext context)
+        {
+            FilterMessage = "Value set in OnActionExecuting";
+        }
+    }
+}

test/WebSites/BasicWebSite/Views/Shared/Components/ViewData/Default.cshtml

@@ -0,0 +1,8 @@
+<html>
+    <head>
+        <title>@ViewData["Title"]</title>
+    </head>
+    <body>
+        <span id="message">@ViewData["Message"]</span>
+    </body>
+</html>

test/WebSites/BasicWebSite/Views/ViewDataProperty/ViewDataInViewComponent.cshtml

@@ -0,0 +1,2 @@
+Sample that shows value of ViewDataAttribute being passed to a ViewComponent
+<span class="view-data">@ViewData["Message"]</span>

test/WebSites/BasicWebSite/Views/ViewDataProperty/ViewDataPropertyToView.cshtml

@@ -0,0 +1,2 @@
+@{ Layout = "_Layout"; }
+Sample that shows ViewDataAttribute being applied to a controller

test/WebSites/BasicWebSite/Views/ViewDataProperty/_Layout.cshtml

@@ -0,0 +1,10 @@
+<html>
+    <head>
+        <title>@ViewData["Title"]</title>
+    </head>
+    <body>
+        <span id="message">@ViewData["Message"]</span>
+        <span id="filter-message">@ViewData["FilterMessage"]</span>
+        @RenderBody()
+    </body>
+</html>

test/WebSites/RazorPagesWebSite/Components/ViewDataViewComponent.cs

@@ -0,0 +1,15 @@
+// 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;
+
+namespace RazorPagesWebSite.Components
+{
+    public class ViewDataViewComponent : ViewComponent
+    {
+        public IViewComponentResult Invoke()
+        {
+            return View();
+        }
+    }
+}

test/WebSites/RazorPagesWebSite/Pages/Shared/Components/ViewData/Default.cshtml

@@ -0,0 +1,8 @@
+<html>
+    <head>
+        <title>@ViewData["Title"]</title>
+    </head>
+    <body>
+        <span id="message">@ViewData["Message"]</span>
+    </body>
+</html>

test/WebSites/RazorPagesWebSite/Pages/ViewData/ViewDataInPage.cs

@@ -0,0 +1,32 @@
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Mvc.Filters;
+using Microsoft.AspNetCore.Mvc.RazorPages;
+
+namespace RazorPagesWebSite
+{
+    public class ViewDataInPage : PageModel
+    {
+        [ViewData]
+        public string Title => "Title with default value";
+
+        [ViewData]
+        public string Keywords { get; set; }
+
+        [ViewData]
+        public  string Description { get; set;}
+
+        [ViewData(Key = "Author")]
+        public string AuthorName { get; set; }
+
+        public void OnGet()
+        {
+            Description = "Description set in handler";
+            AuthorName = "Property with key";
+        }
+
+        public override void OnPageHandlerExecuting(PageHandlerExecutingContext context)
+        {
+            Keywords = "Value set in filter";
+        }
+    }
+}

test/WebSites/RazorPagesWebSite/Pages/ViewData/ViewDataInPage.cshtml

@@ -0,0 +1,6 @@
+@page
+@model ViewDataInPage
+@{
+    Layout = "_Layout";
+}
+Sample that shows ViewData attributes being set in a PageModel.

test/WebSites/RazorPagesWebSite/Pages/ViewData/ViewDataInPageWithoutModel.cshtml

@@ -0,0 +1,18 @@
+@page
+@{
+    Layout = "_Layout";
+}
+@functions
+{
+    [ViewData]
+    public string Title { get; set; } = "Default value";
+
+    [ViewData]
+    public string Description { get; set; }
+
+    public void OnGet()
+    {
+        Description = "Description set in page handler";
+    }
+}
+Sample that shows ViewData being set from a page without handler.

test/WebSites/RazorPagesWebSite/Pages/ViewData/ViewDataToViewComponentPage.cs

@@ -0,0 +1,25 @@
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Mvc.Filters;
+using Microsoft.AspNetCore.Mvc.RazorPages;
+using RazorPagesWebSite.Components;
+
+namespace RazorPagesWebSite
+{
+    public class ViewDataToViewComponentPage : PageModel
+    {
+        [ViewData]
+        public string Title => "View Data in Pages";
+
+        [ViewData]
+        public string Message { get; private set; }
+
+        public IActionResult OnGet()
+        {
+            Message = "Message set in handler";
+            return new ViewComponentResult
+            {
+                ViewComponentType = typeof(ViewDataViewComponent),
+            };
+        }
+    }
+}

test/WebSites/RazorPagesWebSite/Pages/ViewData/ViewDataToViewComponentPage.cshtml

@@ -0,0 +1,2 @@
+@page
+@model ViewDataToViewComponentPage

test/WebSites/RazorPagesWebSite/Pages/ViewData/_Layout.cshtml

@@ -0,0 +1,11 @@
+<html>
+    <head>
+        <meta name="description" content="@ViewData["Description"]" />
+        <meta name="keywords" content="@ViewData["Keywords"]" />
+        <meta name="author" content="@ViewData["Author"]" />
+        <title>@ViewData["Title"]</title>
+    </head>
+    <body>
+        @RenderBody()
+    </body>
+</html>

test/WebSites/RazorPagesWebSite/Pages/ViewData/_ViewImports.cshtml

@@ -0,0 +1 @@
+@addTagHelper "*, Microsoft.AspNetCore.Mvc.TagHelpers"