Add support for page precompilation

src/Microsoft.AspNetCore.Mvc.Razor/Compilation/CompiledViewManfiest.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.IO;
+using System.Reflection;
+#if NETSTANDARD1_6
+using System.Runtime.Loader;
+#endif
+using Microsoft.AspNetCore.Mvc.ApplicationParts;
+
+namespace Microsoft.AspNetCore.Mvc.Razor.Compilation
+{
+    public static class CompiledViewManfiest
+    {
+        public static readonly string PrecompiledViewsAssemblySuffix = ".PrecompiledViews";
+
+        public static Type GetManifestType(AssemblyPart assemblyPart, string typeName)
+        {
+            EnsureFeatureAssembly(assemblyPart);
+
+            var precompiledAssemblyName = new AssemblyName(assemblyPart.Assembly.FullName);
+            precompiledAssemblyName.Name = precompiledAssemblyName.Name + PrecompiledViewsAssemblySuffix;
+
+            return Type.GetType($"{typeName},{precompiledAssemblyName}");
+        }
+
+        private static void EnsureFeatureAssembly(AssemblyPart assemblyPart)
+        {
+#if NETSTANDARD1_6
+            if (assemblyPart.Assembly.IsDynamic || string.IsNullOrEmpty(assemblyPart.Assembly.Location))
+            {
+                return;
+            }
+
+            var precompiledAssemblyFileName = assemblyPart.Assembly.GetName().Name
+                + PrecompiledViewsAssemblySuffix
+                + ".dll";
+            var precompiledAssemblyFilePath = Path.Combine(
+                Path.GetDirectoryName(assemblyPart.Assembly.Location),
+                precompiledAssemblyFileName);
+
+            if (File.Exists(precompiledAssemblyFilePath))
+            {
+                try
+                {
+                    AssemblyLoadContext.Default.LoadFromAssemblyPath(precompiledAssemblyFilePath);
+                }
+                catch (FileLoadException)
+                {
+                    // Don't throw if assembly cannot be loaded. This can happen if the file is not a managed assembly.
+                }
+            }
+#elif NET46
+#else
+#error target frameworks needs to be updated.
+#endif
+        }
+    }
+}

src/Microsoft.AspNetCore.Mvc.Razor/Compilation/ViewsFeatureProvider.cs

@@ -3,9 +3,7 @@
 
 using System;
 using System.Collections.Generic;
-using System.IO;
 using System.Linq;
-using System.Reflection;
 using Microsoft.AspNetCore.Mvc.ApplicationParts;
 
 namespace Microsoft.AspNetCore.Mvc.Razor.Compilation
@@ -15,9 +13,6 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Compilation
     /// </summary>
     public class ViewsFeatureProvider : IApplicationFeatureProvider<ViewsFeature>
     {
-        /// <summary>
-        /// Gets the suffix for the view assembly.
-        /// </summary>
         public static readonly string PrecompiledViewsAssemblySuffix = ".PrecompiledViews";
 
         /// <summary>
@@ -30,19 +25,19 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Compilation
         /// </summary>
         public static readonly string ViewInfoContainerTypeName = "__PrecompiledViewCollection";
 
+        private static readonly string FullyQualifiedManifestTypeName = ViewInfoContainerNamespace + "." + ViewInfoContainerTypeName;
+
         /// <inheritdoc />
         public void PopulateFeature(IEnumerable<ApplicationPart> parts, ViewsFeature feature)
         {
             foreach (var assemblyPart in parts.OfType<AssemblyPart>())
             {
-                var viewInfoContainerTypeName = GetViewInfoContainerType(assemblyPart);
+                var viewContainer = GetManifest(assemblyPart);
-                if (viewInfoContainerTypeName == null)
+                if (viewContainer == null)
                 {
                     continue;
                 }
 
-                var viewContainer = (ViewInfoContainer)Activator.CreateInstance(viewInfoContainerTypeName);
-
                 foreach (var item in viewContainer.ViewInfos)
                 {
                     feature.Views[item.Path] = item.Type;
@@ -55,40 +50,15 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Compilation
         /// </summary>
         /// <param name="assemblyPart">The <see cref="AssemblyPart"/>.</param>
         /// <returns>The <see cref="ViewInfoContainer"/> <see cref="Type"/>.</returns>
-        protected virtual Type GetViewInfoContainerType(AssemblyPart assemblyPart)
+        protected virtual ViewInfoContainer GetManifest(AssemblyPart assemblyPart)
         {
-#if NETSTANDARD1_6
+            var type = CompiledViewManfiest.GetManifestType(assemblyPart, FullyQualifiedManifestTypeName);
-            if (!assemblyPart.Assembly.IsDynamic && !string.IsNullOrEmpty(assemblyPart.Assembly.Location))
+            if (type != null)
             {
-                var precompiledAssemblyFileName = assemblyPart.Assembly.GetName().Name
+                return (ViewInfoContainer)Activator.CreateInstance(type);
-                    + PrecompiledViewsAssemblySuffix
-                    + ".dll";
-                var precompiledAssemblyFilePath = Path.Combine(
-                    Path.GetDirectoryName(assemblyPart.Assembly.Location),
-                    precompiledAssemblyFileName);
-
-                if (File.Exists(precompiledAssemblyFilePath))
-                {
-                    try
-                    {
-                        System.Runtime.Loader.AssemblyLoadContext.Default.LoadFromAssemblyPath(precompiledAssemblyFilePath);
-                    }
-                    catch (FileLoadException)
-                    {
-                        // Don't throw if assembly cannot be loaded. This can happen if the file is not a managed assembly.
-                    }
-                }
             }
-#elif NET46
-#else
-#error target frameworks needs to be updated.
-#endif
 
-            var precompiledAssemblyName = new AssemblyName(assemblyPart.Assembly.FullName);
+            return null;
-            precompiledAssemblyName.Name = precompiledAssemblyName.Name + PrecompiledViewsAssemblySuffix;
-
-            var typeName = $"{ViewInfoContainerNamespace}.{ViewInfoContainerTypeName},{precompiledAssemblyName}";
-            return Type.GetType(typeName);
         }
     }
 }

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

@@ -135,10 +135,8 @@ namespace Microsoft.Extensions.DependencyInjection
 
             // DependencyContextRazorViewEngineOptionsSetup needs to run after RazorViewEngineOptionsSetup.
             // The ordering of the following two lines is important to ensure this behavior.
-#pragma warning disable 0618
             services.TryAddEnumerable(
                 ServiceDescriptor.Transient<IConfigureOptions<RazorViewEngineOptions>, RazorViewEngineOptionsSetup>());
-#pragma warning restore 0618
             services.TryAddEnumerable(
                 ServiceDescriptor.Transient<
                     IConfigureOptions<RazorViewEngineOptions>,

src/Microsoft.AspNetCore.Mvc.RazorPages/ApplicationModels/IPageApplicationModelProvider.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.
+
+namespace Microsoft.AspNetCore.Mvc.ApplicationModels
+{
+    /// <summary>
+    /// Builds or modifies an <see cref="PageApplicationModelProviderContext"/> for Razor Page discovery.
+    /// </summary>
+    public interface IPageApplicationModelProvider
+    {
+        /// <summary>
+        /// Gets the order value for determining the order of execution of providers. Providers execute in
+        /// ascending numeric value of the <see cref="Order"/> property.
+        /// </summary>
+        /// <remarks>
+        /// <para>
+        /// Providers are executed in an ordering determined by an ascending sort of the <see cref="Order"/> property.
+        /// A provider with a lower numeric value of <see cref="Order"/> will have its
+        /// <see cref="OnProvidersExecuting"/> called before that of a provider with a higher numeric value of
+        /// <see cref="Order"/>. The <see cref="OnProvidersExecuted"/> method is called in the reverse ordering after
+        /// all calls to <see cref="OnProvidersExecuting"/>. A provider with a lower numeric value of
+        /// <see cref="Order"/> will have its <see cref="OnProvidersExecuted"/> method called after that of a provider
+        /// with a higher numeric value of <see cref="Order"/>.
+        /// </para>
+        /// <para>
+        /// If two providers have the same numeric value of <see cref="Order"/>, then their relative execution order
+        /// is undefined.
+        /// </para>
+        /// </remarks>
+        int Order { get; }
+
+        /// <summary>
+        /// Executed for the first pass of building <see cref="PageApplicationModel"/> instances. See <see cref="Order"/>.
+        /// </summary>
+        /// <param name="context">The <see cref="PageApplicationModelProviderContext"/>.</param>
+        void OnProvidersExecuting(PageApplicationModelProviderContext context);
+
+        /// <summary>
+        /// Executed for the second pass of building <see cref="PageApplicationModel"/> instances. See <see cref="Order"/>.
+        /// </summary>
+        /// <param name="context">The <see cref="PageApplicationModelProviderContext"/>.</param>
+        void OnProvidersExecuted(PageApplicationModelProviderContext context);
+    }
+}

src/Microsoft.AspNetCore.Mvc.RazorPages/ApplicationModels/PageApplicationModel.cs

@@ -59,17 +59,17 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationModels
         }
 
         /// <summary>
-        /// Gets or sets the application root relative path for the page.
+        /// Gets the application root relative path for the page.
         /// </summary>
         public string RelativePath { get; }
 
         /// <summary>
-        /// Gets or sets the path relative to the base path for page discovery.
+        /// Gets the path relative to the base path for page discovery.
         /// </summary>
         public string ViewEnginePath { get; }
 
         /// <summary>
-        /// Gets or sets the applicable <see cref="IFilterMetadata"/> instances.
+        /// Gets the applicable <see cref="IFilterMetadata"/> instances.
         /// </summary>
         public IList<IFilterMetadata> Filters { get; }
 
@@ -79,7 +79,7 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationModels
         public IDictionary<object, object> Properties { get; }
 
         /// <summary>
-        /// Gets or sets the <see cref="SelectorModel"/> instances.
+        /// Gets the <see cref="SelectorModel"/> instances.
         /// </summary>
         public IList<SelectorModel> Selectors { get; }
     }

src/Microsoft.AspNetCore.Mvc.RazorPages/ApplicationModels/PageApplicationModelProviderContext.cs

@@ -0,0 +1,18 @@
+// 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;
+
+namespace Microsoft.AspNetCore.Mvc.ApplicationModels
+{
+    /// <summary>
+    /// A context object for <see cref="IPageApplicationModelProvider"/>.
+    /// </summary>
+    public class PageApplicationModelProviderContext
+    {
+        /// <summary>
+        /// Gets the <see cref="PageApplicationModel"/> instances.
+        /// </summary>
+        public IList<PageApplicationModel> Results { get; } = new List<PageApplicationModel>();
+    }
+}

src/Microsoft.AspNetCore.Mvc.RazorPages/ApplicationParts/CompiledPageFeature.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 System.Collections.Generic;
+
+namespace Microsoft.AspNetCore.Mvc.ApplicationParts
+{
+    public class CompiledPageInfoFeature
+    {
+        public IList<CompiledPageInfo> CompiledPages { get; } = new List<CompiledPageInfo>();
+    }
+}

src/Microsoft.AspNetCore.Mvc.RazorPages/ApplicationParts/CompiledPageFeatureProvider.cs

@@ -0,0 +1,53 @@
+// 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.Mvc.Razor.Compilation;
+using Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure;
+
+namespace Microsoft.AspNetCore.Mvc.ApplicationParts
+{
+    /// <summary>
+    /// An <see cref="IApplicationFeatureProvider{TFeature}"/> for <see cref="ViewsFeature"/>.
+    /// </summary>
+    public class CompiledPageFeatureProvider : IApplicationFeatureProvider<ViewsFeature>
+    {
+        /// <summary>
+        /// Gets the namespace for the <see cref="ViewInfoContainer"/> type in the view assembly.
+        /// </summary>
+        public static readonly string CompiledPageManifestNamespace = "AspNetCore";
+
+        /// <summary>
+        /// Gets the type name for the view collection type in the view assembly.
+        /// </summary>
+        public static readonly string CompiledPageManifestTypeName = "__CompiledRazorPagesManifest";
+
+        private static readonly string FullyQualifiedManifestTypeName =
+            CompiledPageManifestNamespace + "." + CompiledPageManifestTypeName;
+
+        /// <inheritdoc />
+        public void PopulateFeature(IEnumerable<ApplicationPart> parts, ViewsFeature feature)
+        {
+            foreach (var item in GetCompiledPageInfo(parts))
+            {
+                feature.Views.Add(item.Path, item.CompiledType);
+            }
+        }
+
+        /// <summary>
+        /// Gets the sequence of <see cref="CompiledPageInfo"/> from <paramref name="parts"/>.
+        /// </summary>
+        /// <param name="parts">The <see cref="ApplicationPart"/>s</param>
+        /// <returns>The sequence of <see cref="CompiledPageInfo"/>.</returns>
+        public static IEnumerable<CompiledPageInfo> GetCompiledPageInfo(IEnumerable<ApplicationPart> parts)
+        {
+            return parts.OfType<AssemblyPart>()
+                .Select(part => CompiledViewManfiest.GetManifestType(part, FullyQualifiedManifestTypeName))
+                .Where(type => type != null)
+                .Select(type => (CompiledPageManifest)Activator.CreateInstance(type))
+                .SelectMany(manifest => manifest.CompiledPages);
+        }
+    }
+}

src/Microsoft.AspNetCore.Mvc.RazorPages/ApplicationParts/CompiledPageInfo.cs

@@ -0,0 +1,23 @@
+// 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;
+
+namespace Microsoft.AspNetCore.Mvc.ApplicationParts
+{
+    public class CompiledPageInfo
+    {
+        public CompiledPageInfo(string path, Type compiledType, string routePrefix)
+        {
+            Path = path;
+            CompiledType = compiledType;
+            RoutePrefix = routePrefix;
+        }
+
+        public string Path { get; }
+
+        public string RoutePrefix { get; }
+
+        public Type CompiledType { get; }
+    }
+}

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

@@ -2,9 +2,11 @@
 // 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.Abstractions;
+using Microsoft.AspNetCore.Mvc.ApplicationModels;
+using Microsoft.AspNetCore.Mvc.ApplicationParts;
 using Microsoft.AspNetCore.Mvc.Infrastructure;
-using Microsoft.AspNetCore.Mvc.Razor;
 using Microsoft.AspNetCore.Mvc.RazorPages;
 using Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure;
 using Microsoft.AspNetCore.Mvc.RazorPages.Internal;
@@ -24,13 +26,16 @@ namespace Microsoft.Extensions.DependencyInjection
             }
 
             builder.AddRazorViewEngine();
+
+            AddFeatureProviders(builder);
             AddServices(builder.Services);
+
             return builder;
         }
 
         public static IMvcCoreBuilder AddRazorPages(
             this IMvcCoreBuilder builder,
-            Action<RazorViewEngineOptions> setupAction)
+            Action<RazorPagesOptions> setupAction)
         {
             if (builder == null)
             {
@@ -43,6 +48,8 @@ namespace Microsoft.Extensions.DependencyInjection
             }
 
             builder.AddRazorViewEngine();
+
+            AddFeatureProviders(builder);
             AddServices(builder.Services);
 
             builder.Services.Configure(setupAction);
@@ -50,6 +57,14 @@ namespace Microsoft.Extensions.DependencyInjection
             return builder;
         }
 
+        private static void AddFeatureProviders(IMvcCoreBuilder builder)
+        {
+            if (!builder.PartManager.FeatureProviders.OfType<CompiledPageFeatureProvider>().Any())
+            {
+                builder.PartManager.FeatureProviders.Add(new CompiledPageFeatureProvider());
+            }
+        }
+
         // Internal for testing.
         internal static void AddServices(IServiceCollection services)
         {
@@ -57,10 +72,14 @@ namespace Microsoft.Extensions.DependencyInjection
             services.TryAddEnumerable(
                 ServiceDescriptor.Transient<IConfigureOptions<RazorPagesOptions>, RazorPagesOptionsSetup>());
 
-            // Action Invoker
+            // Action description and invocation
             services.TryAddEnumerable(
                 ServiceDescriptor.Singleton<IActionDescriptorProvider, PageActionDescriptorProvider>());
             services.TryAddSingleton<IActionDescriptorChangeProvider, PageActionDescriptorChangeProvider>();
+            services.TryAddEnumerable(
+                ServiceDescriptor.Singleton<IPageApplicationModelProvider, RazorProjectPageApplicationModelProvider>());
+            services.TryAddEnumerable(
+                ServiceDescriptor.Singleton<IPageApplicationModelProvider, CompiledPageApplicationModelProvider>());
 
             services.TryAddEnumerable(
                 ServiceDescriptor.Singleton<IActionInvokerProvider, PageActionInvokerProvider>());

src/Microsoft.AspNetCore.Mvc.RazorPages/Infrastructure/CompiledPageManifest.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.Collections.Generic;
+using Microsoft.AspNetCore.Mvc.ApplicationParts;
+
+namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
+{
+    public abstract class CompiledPageManifest
+    {
+        /// <summary>
+        /// Initializes a new instance of <see cref="CompiledPageManifest"/>.
+        /// </summary>
+        /// <param name="pages">The sequence of <see cref="CompiledPageInfo"/>.</param>
+        public CompiledPageManifest(IReadOnlyList<CompiledPageInfo> pages)
+        {
+            CompiledPages = pages;
+        }
+
+        /// <summary>
+        /// The <see cref="IReadOnlyList{T}"/> of <see cref="CompiledPageInfo"/>.
+        /// </summary>
+        public IReadOnlyList<CompiledPageInfo> CompiledPages { get; }
+    }
+}

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

@@ -3,29 +3,27 @@
 
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using Microsoft.AspNetCore.Mvc.Abstractions;
 using Microsoft.AspNetCore.Mvc.ApplicationModels;
 using Microsoft.AspNetCore.Mvc.Filters;
 using Microsoft.AspNetCore.Mvc.Routing;
-using Microsoft.AspNetCore.Mvc.ViewFeatures.Internal;
-using Microsoft.AspNetCore.Razor.Language;
 using Microsoft.Extensions.Options;
 
 namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
 {
     public class PageActionDescriptorProvider : IActionDescriptorProvider
     {
-        private static readonly string IndexFileName = "Index.cshtml";
+        private readonly List<IPageApplicationModelProvider> _applicationModelProviders;
-        private readonly RazorProject _project;
         private readonly MvcOptions _mvcOptions;
         private readonly RazorPagesOptions _pagesOptions;
 
         public PageActionDescriptorProvider(
-            RazorProject project,
+            IEnumerable<IPageApplicationModelProvider> pageMetadataProviders,
             IOptions<MvcOptions> mvcOptionsAccessor,
             IOptions<RazorPagesOptions> pagesOptionsAccessor)
         {
-            _project = project;
+            _applicationModelProviders = pageMetadataProviders.OrderBy(p => p.Order).ToList();
             _mvcOptions = mvcOptionsAccessor.Value;
             _pagesOptions = pagesOptionsAccessor.Value;
         }
@@ -34,57 +32,37 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
 
         public void OnProvidersExecuting(ActionDescriptorProviderContext context)
         {
-            foreach (var item in _project.EnumerateItems(_pagesOptions.RootDirectory))
+            var pageApplicationModels = BuildModel();
+
+            for (var i = 0; i < pageApplicationModels.Count; i++)
             {
-                if (item.FileName.StartsWith("_"))
+                AddActionDescriptors(context.Results, pageApplicationModels[i]);
-                {
-                    // Files like _ViewImports.cshtml should not be routable.
-                    continue;
-                }
-
-                string template;
-                if (!PageDirectiveFeature.TryGetPageDirective(item, out template))
-                {
-                    // .cshtml pages without @page are not RazorPages.
-                    continue;
-                }
-
-                if (AttributeRouteModel.IsOverridePattern(template))
-                {
-                    throw new InvalidOperationException(string.Format(
-                        Resources.PageActionDescriptorProvider_RouteTemplateCannotBeOverrideable,
-                        item.Path));
-                }
-
-                AddActionDescriptors(context.Results, item, template);
             }
         }
 
+        protected IList<PageApplicationModel> BuildModel()
+        {
+            var context = new PageApplicationModelProviderContext();
+
+            for (var i = 0; i < _applicationModelProviders.Count; i++)
+            {
+                _applicationModelProviders[i].OnProvidersExecuting(context);
+            }
+
+            for (var i = _applicationModelProviders.Count - 1; i >= 0; i--)
+            {
+                _applicationModelProviders[i].OnProvidersExecuted(context);
+            }
+
+            return context.Results;
+        }
+
         public void OnProvidersExecuted(ActionDescriptorProviderContext context)
         {
         }
 
-        private void AddActionDescriptors(IList<ActionDescriptor> actions, RazorProjectItem item, string template)
+        private void AddActionDescriptors(IList<ActionDescriptor> actions, PageApplicationModel model)
         {
-            var model = new PageApplicationModel(item.CombinedPath, item.PathWithoutExtension);
-            var routePrefix = item.PathWithoutExtension;
-            model.Selectors.Add(CreateSelectorModel(routePrefix, template));
-
-            if (string.Equals(IndexFileName, item.FileName, StringComparison.OrdinalIgnoreCase))
-            {
-                var parentDirectoryPath = item.Path;
-                var index = parentDirectoryPath.LastIndexOf('/');
-                if (index == -1)
-                {
-                    parentDirectoryPath = string.Empty;
-                }
-                else
-                {
-                    parentDirectoryPath = parentDirectoryPath.Substring(0, index);
-                }
-                model.Selectors.Add(CreateSelectorModel(parentDirectoryPath, template));
-            }
-
             for (var i = 0; i < _pagesOptions.Conventions.Count; i++)
             {
                 _pagesOptions.Conventions[i].Apply(model);
@@ -111,28 +89,17 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
                         Order = selector.AttributeRouteModel.Order ?? 0,
                         Template = selector.AttributeRouteModel.Template,
                     },
-                    DisplayName = $"Page: {item.Path}",
+                    DisplayName = $"Page: {model.ViewEnginePath}",
                     FilterDescriptors = filters,
                     Properties = new Dictionary<object, object>(model.Properties),
-                    RelativePath = item.CombinedPath,
+                    RelativePath = model.RelativePath,
                     RouteValues = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
                     {
-                        { "page", item.PathWithoutExtension },
+                        { "page", model.ViewEnginePath},
                     },
-                    ViewEnginePath = item.Path,
+                    ViewEnginePath = model.ViewEnginePath,
                 });
             }
         }
-
-        private static SelectorModel CreateSelectorModel(string prefix, string template)
-        {
-            return new SelectorModel
-            {
-                AttributeRouteModel = new AttributeRouteModel
-                {
-                    Template = AttributeRouteModel.CombineTemplates(prefix, template),
-                }
-            };
-        }
     }
 }

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

@@ -16,16 +16,25 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
                 throw new ArgumentNullException(nameof(projectItem));
             }
 
+            return TryGetPageDirective(projectItem.Read, out template);
+        }
+
+        public static bool TryGetPageDirective(Func<Stream> streamFactory, out string template)
+        {
+            if (streamFactory == null)
+            {
+                throw new ArgumentNullException(nameof(streamFactory));
+            }
+
             const string PageDirective = "@page";
 
-            var stream = projectItem.Read();
+            string content;
-
+            using (var streamReader = new StreamReader(streamFactory()))
-            string content = null;
-            using (var streamReader = new StreamReader(stream))
             {
                 do
                 {
                     content = streamReader.ReadLine();
+
                 } while (content != null && string.IsNullOrWhiteSpace(content));
                 content = content?.Trim();
             }

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

@@ -0,0 +1,97 @@
+// 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.ApplicationModels;
+using Microsoft.AspNetCore.Mvc.ApplicationParts;
+using Microsoft.Extensions.Options;
+
+namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
+{
+    public class CompiledPageApplicationModelProvider : IPageApplicationModelProvider
+    {
+        private readonly object _cacheLock = new object();
+        private readonly ApplicationPartManager _applicationManager;
+        private readonly RazorPagesOptions _pagesOptions;
+        private List<PageApplicationModel> _cachedApplicationModels;
+
+        public CompiledPageApplicationModelProvider(
+            ApplicationPartManager applicationManager,
+            IOptions<RazorPagesOptions> pagesOptionsAccessor)
+        {
+            _applicationManager = applicationManager;
+            _pagesOptions = pagesOptionsAccessor.Value;
+        }
+
+        public int Order => -1000;
+
+        public void OnProvidersExecuting(PageApplicationModelProviderContext context)
+        {
+            EnsureCache();
+            for (var i = 0; i < _cachedApplicationModels.Count; i++)
+            {
+                var pageModel = _cachedApplicationModels[i];
+                context.Results.Add(new PageApplicationModel(pageModel));
+            }
+        }
+
+        public void OnProvidersExecuted(PageApplicationModelProviderContext context)
+        {
+        }
+
+        private void EnsureCache()
+        {
+            lock (_cacheLock)
+            {
+                if (_cachedApplicationModels != null)
+                {
+                    return;
+                }
+
+                var rootDirectory = _pagesOptions.RootDirectory;
+                if (!rootDirectory.EndsWith("/", StringComparison.Ordinal))
+                {
+                    rootDirectory = rootDirectory + "/";
+                }
+
+                var cachedApplicationModels = new List<PageApplicationModel>();
+                var pages = GetCompiledPages();
+                foreach (var page in pages)
+                {
+                    if (!page.Path.StartsWith(rootDirectory))
+                    {
+                        continue;
+                    }
+
+                    var viewEnginePath = GetViewEnginePath(rootDirectory, page.Path);
+                    var model = new PageApplicationModel(page.Path, viewEnginePath);
+                    PageSelectorModel.PopulateDefaults(model, page.RoutePrefix);
+
+                    cachedApplicationModels.Add(model);
+                }
+
+                _cachedApplicationModels = cachedApplicationModels;
+            }
+        }
+
+        protected virtual IEnumerable<CompiledPageInfo> GetCompiledPages()
+            => CompiledPageFeatureProvider.GetCompiledPageInfo(_applicationManager.ApplicationParts);
+
+        private string GetViewEnginePath(string rootDirectory, string path)
+        {
+            var endIndex = path.LastIndexOf('.');
+            if (endIndex == -1)
+            {
+                endIndex = path.Length;
+            }
+
+            // rootDirectory = "/Pages/AllMyPages/"
+            // path = "/Pages/AllMyPages/Home.cshtml"
+            // Result = "/Home"
+            var startIndex = rootDirectory.Length - 1;
+
+            return path.Substring(startIndex, endIndex - startIndex);
+        }
+    }
+}

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

@@ -216,13 +216,10 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
                 ViewStartFileName);
             foreach (var item in viewStartItems)
             {
-                if (item.Exists)
+                var factoryResult = _razorPageFactoryProvider.CreateFactory(item.Path);
+                if (factoryResult.Success)
                 {
-                    var factoryResult = _razorPageFactoryProvider.CreateFactory(item.Path);
+                    viewStartFactories.Insert(0, factoryResult.RazorPageFactory);
-                    if (factoryResult.Success)
-                    {
-                        viewStartFactories.Insert(0, factoryResult.RazorPageFactory);
-                    }
                 }
             }
 

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

@@ -0,0 +1,53 @@
+// 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.IO;
+using Microsoft.AspNetCore.Mvc.ApplicationModels;
+
+namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
+{
+    public static class PageSelectorModel
+    {
+        private const string IndexFileName = "Index.cshtml";
+
+        public static void PopulateDefaults(PageApplicationModel model, string routeTemplate)
+        {
+            if (AttributeRouteModel.IsOverridePattern(routeTemplate))
+            {
+                throw new InvalidOperationException(string.Format(
+                    Resources.PageActionDescriptorProvider_RouteTemplateCannotBeOverrideable,
+                    model.RelativePath));
+            }
+
+            model.Selectors.Add(CreateSelectorModel(model.ViewEnginePath, routeTemplate));
+
+            var fileName = Path.GetFileName(model.RelativePath);
+            if (string.Equals(IndexFileName, fileName, StringComparison.OrdinalIgnoreCase))
+            {
+                var parentDirectoryPath = model.ViewEnginePath;
+                var index = parentDirectoryPath.LastIndexOf('/');
+                if (index == -1)
+                {
+                    parentDirectoryPath = string.Empty;
+                }
+                else
+                {
+                    parentDirectoryPath = parentDirectoryPath.Substring(0, index);
+                }
+                model.Selectors.Add(CreateSelectorModel(parentDirectoryPath, routeTemplate));
+            }
+        }
+
+        private static SelectorModel CreateSelectorModel(string prefix, string template)
+        {
+            return new SelectorModel
+            {
+                AttributeRouteModel = new AttributeRouteModel
+                {
+                    Template = AttributeRouteModel.CombineTemplates(prefix, template),
+                }
+            };
+        }
+    }
+}

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

@@ -0,0 +1,55 @@
+// 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.ApplicationModels;
+using Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure;
+using Microsoft.AspNetCore.Razor.Language;
+using Microsoft.Extensions.Options;
+
+namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
+{
+    public class RazorProjectPageApplicationModelProvider : IPageApplicationModelProvider
+    {
+        private readonly RazorProject _project;
+        private readonly RazorPagesOptions _pagesOptions;
+
+        public RazorProjectPageApplicationModelProvider(
+            RazorProject razorProject,
+            IOptions<RazorPagesOptions> pagesOptionsAccessor)
+        {
+            _project = razorProject;
+            _pagesOptions = pagesOptionsAccessor.Value;
+        }
+
+        public int Order => -1000;
+
+        public void OnProvidersExecuted(PageApplicationModelProviderContext context)
+        {
+        }
+
+        public void OnProvidersExecuting(PageApplicationModelProviderContext context)
+        {
+            foreach (var item in _project.EnumerateItems(_pagesOptions.RootDirectory))
+            {
+                if (item.FileName.StartsWith("_"))
+                {
+                    // Pages like _ViewImports should not be routable.
+                    continue;
+                }
+
+                if (!PageDirectiveFeature.TryGetPageDirective(item, out var routeTemplate))
+                {
+                    // .cshtml pages without @page are not RazorPages.
+                    continue;
+                }
+
+                var pageApplicationModel = new PageApplicationModel(
+                    relativePath: item.CombinedPath,
+                    viewEnginePath: item.PathWithoutExtension);
+                PageSelectorModel.PopulateDefaults(pageApplicationModel, routeTemplate);
+
+                context.Results.Add(pageApplicationModel);
+            }
+        }
+    }
+}

test/Microsoft.AspNetCore.Mvc.Razor.Test/Compilation/ViewsFeatureProviderTest.cs

@@ -121,8 +121,11 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Compilation
                 _containerLookup = containerLookup;
             }
 
-            protected override Type GetViewInfoContainerType(AssemblyPart assemblyPart) =>
+            protected override ViewInfoContainer GetManifest(AssemblyPart assemblyPart)
-                _containerLookup[assemblyPart];
+            {
+                var type = _containerLookup[assemblyPart];
+                return (ViewInfoContainer)Activator.CreateInstance(type);
+            }
         }
 
         private class ViewInfoContainer1 : ViewInfoContainer

test/Microsoft.AspNetCore.Mvc.RazorPages.Test/Infrastructure/PageActionDescriptorProviderTest.cs

@@ -19,17 +19,12 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
     public class PageActionDescriptorProviderTest
     {
         [Fact]
-        public void GetDescriptors_DoesNotAddDescriptorsForFilesWithoutDirectives()
+        public void GetDescriptors_DoesNotAddDescriptorsIfNoApplicationModelsAreDiscovered()
         {
             // Arrange
-            var razorProject = new Mock<RazorProject>();
+            var applicationModelProvider = new TestPageApplicationModelProvider();
-            razorProject.Setup(p => p.EnumerateItems("/"))
-                .Returns(new[]
-                {
-                    GetProjectItem("/", "/Index.cshtml", "<h1>Hello world</h1>"),
-                });
             var provider = new PageActionDescriptorProvider(
-                razorProject.Object,
+                new[] { applicationModelProvider },
                 GetAccessor<MvcOptions>(),
                 GetRazorPagesOptions());
             var context = new ActionDescriptorProviderContext();
@@ -42,17 +37,25 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
         }
 
         [Fact]
-        public void GetDescriptors_AddsDescriptorsForFileWithPageDirective()
+        public void GetDescriptors_AddsDescriptorsForModelWithSelector()
         {
             // Arrange
-            var razorProject = new Mock<RazorProject>();
+            var model = new PageApplicationModel("/Test.cshtml", "/Test")
-            razorProject.Setup(p => p.EnumerateItems("/"))
+            {
-                .Returns(new[]
+                Selectors =
                 {
-                    GetProjectItem("/", "/Test.cshtml", $"@page{Environment.NewLine}<h1>Hello world</h1>"),
+                    new SelectorModel
-                });
+                    {
+                        AttributeRouteModel = new AttributeRouteModel
+                        {
+                            Template = "/Test/{id:int?}",
+                        }
+                    }
+                }
+            };
+            var applicationModelProvider = new TestPageApplicationModelProvider(model);
             var provider = new PageActionDescriptorProvider(
-                razorProject.Object,
+                new[] { applicationModelProvider },
                 GetAccessor<MvcOptions>(),
                 GetRazorPagesOptions());
             var context = new ActionDescriptorProviderContext();
@@ -65,53 +68,49 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
             var descriptor = Assert.IsType<PageActionDescriptor>(result);
             Assert.Equal("/Test.cshtml", descriptor.RelativePath);
             Assert.Equal("/Test", descriptor.RouteValues["page"]);
-            Assert.Equal("Test", descriptor.AttributeRouteInfo.Template);
+            Assert.Equal("/Test/{id:int?}", descriptor.AttributeRouteInfo.Template);
         }
 
         [Fact]
-        public void GetDescriptors_AddsDescriptorsForFileWithPageDirectiveAndRouteTemplate()
+        public void GetDescriptors_AddsActionDescriptorForEachSelector()
         {
             // Arrange
-            var razorProject = new Mock<RazorProject>();
+            var applicationModelProvider = new TestPageApplicationModelProvider(
-            razorProject.Setup(p => p.EnumerateItems("/"))
+                new PageApplicationModel("/base-path/Test.cshtml", "/base-path/Test")
-                .Returns(new[]
                 {
-                    GetProjectItem("/", "/Test.cshtml", $"@page \"Home\" {Environment.NewLine}<h1>Hello world</h1>"),
+                    Selectors =
-                });
+                    {
-            var provider = new PageActionDescriptorProvider(
+                        CreateSelectorModel("base-path/Test/Home")
-                razorProject.Object,
+                    }
-                GetAccessor<MvcOptions>(),
+                },
-                GetRazorPagesOptions());
+                new PageApplicationModel("/base-path/Index.cshtml", "/base-path/Index")
-            var context = new ActionDescriptorProviderContext();
-
-            // Act
-            provider.OnProvidersExecuting(context);
-
-            // Assert
-            var result = Assert.Single(context.Results);
-            var descriptor = Assert.IsType<PageActionDescriptor>(result);
-            Assert.Equal("/Test.cshtml", descriptor.RelativePath);
-            Assert.Equal("/Test", descriptor.RouteValues["page"]);
-            Assert.Equal("Test/Home", descriptor.AttributeRouteInfo.Template);
-        }
-
-        [Fact]
-        public void GetDescriptors_GeneratesRouteTemplate()
-        {
-            // Arrange
-            var razorProject = new Mock<RazorProject>(MockBehavior.Strict);
-            razorProject.Setup(p => p.EnumerateItems("/"))
-                .Returns(new[]
                 {
-                    GetProjectItem("/", "/base-path/Test.cshtml", $"@page \"Home\" {Environment.NewLine}<h1>Hello world</h1>"),
+                    Selectors =
-                    GetProjectItem("/", "/base-path/Index.cshtml", $"@page {Environment.NewLine}"),
+                    {
-                    GetProjectItem("/", "/base-path/Admin/Index.cshtml", $"@page{Environment.NewLine}"),
+                         CreateSelectorModel("base-path/Index"),
-                    GetProjectItem("/", "/base-path/Admin/User.cshtml", $"@page{Environment.NewLine}"),
+                         CreateSelectorModel("base-path/"),
+                    }
+                },
+                new PageApplicationModel("/base-path/Admin/Index.cshtml", "/base-path/Admin/Index")
+                {
+                    Selectors =
+                    {
+                         CreateSelectorModel("base-path/Admin/Index"),
+                         CreateSelectorModel("base-path/Admin"),
+                    }
+                },
+                new PageApplicationModel("/base-path/Admin/User.cshtml", "/base-path/Admin/User")
+                {
+                    Selectors =
+                    {
+                         CreateSelectorModel("base-path/Admin/User"),
+                    },
                 });
+
             var options = GetRazorPagesOptions();
 
             var provider = new PageActionDescriptorProvider(
-                razorProject.Object,
+                new[] { applicationModelProvider },
                 GetAccessor<MvcOptions>(),
                 options);
             var context = new ActionDescriptorProviderContext();
@@ -123,122 +122,39 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
             Assert.Collection(context.Results,
                 result => Assert.Equal("base-path/Test/Home", result.AttributeRouteInfo.Template),
                 result => Assert.Equal("base-path/Index", result.AttributeRouteInfo.Template),
-                result => Assert.Equal("base-path", result.AttributeRouteInfo.Template),
+                result => Assert.Equal("base-path/", result.AttributeRouteInfo.Template),
                 result => Assert.Equal("base-path/Admin/Index", result.AttributeRouteInfo.Template),
                 result => Assert.Equal("base-path/Admin", result.AttributeRouteInfo.Template),
                 result => Assert.Equal("base-path/Admin/User", result.AttributeRouteInfo.Template));
         }
 
-        [Fact]
+        private static SelectorModel CreateSelectorModel(string template)
-        public void GetDescriptors_UsesBasePathOption_WhenGeneratingRouteTemplate()
         {
-            // Arrange
+            return new SelectorModel
-            var razorProject = new Mock<RazorProject>(MockBehavior.Strict);
+            {
-            razorProject.Setup(p => p.EnumerateItems("/base-path"))
+                AttributeRouteModel = new AttributeRouteModel
-                .Returns(new[]
                 {
-                    GetProjectItem("/base-path", "/Test.cshtml", $"@page \"Home\" {Environment.NewLine}<h1>Hello world</h1>"),
+                    Template = template,
-                    GetProjectItem("/base-path", "/Index.cshtml", $"@page {Environment.NewLine}"),
+                }
-                    GetProjectItem("/base-path", "/Admin/Index.cshtml", $"@page{Environment.NewLine}"),
+            };
-                    GetProjectItem("/base-path", "/Admin/User.cshtml", $"@page{Environment.NewLine}"),
-                });
-            var options = GetRazorPagesOptions();
-            options.Value.RootDirectory = "/base-path";
-            var provider = new PageActionDescriptorProvider(
-                razorProject.Object,
-                GetAccessor<MvcOptions>(),
-                options);
-            var context = new ActionDescriptorProviderContext();
-
-            // Act
-            provider.OnProvidersExecuting(context);
-
-            // Assert
-            Assert.Collection(context.Results,
-                result => Assert.Equal("Test/Home", result.AttributeRouteInfo.Template),
-                result => Assert.Equal("Index", result.AttributeRouteInfo.Template),
-                result => Assert.Equal("", result.AttributeRouteInfo.Template),
-                result => Assert.Equal("Admin/Index", result.AttributeRouteInfo.Template),
-                result => Assert.Equal("Admin", result.AttributeRouteInfo.Template),
-                result => Assert.Equal("Admin/User", result.AttributeRouteInfo.Template));
-
-        }
-
-        [Theory]
-        [InlineData("/Path1")]
-        [InlineData("~/Path1")]
-        public void GetDescriptors_ThrowsIfRouteTemplatesAreOverriden(string template)
-        {
-            // Arrange
-            var razorProject = new Mock<RazorProject>();
-            razorProject.Setup(p => p.EnumerateItems("/"))
-                .Returns(new[]
-                {
-                    GetProjectItem("/", "/Test.cshtml", $"@page \"{template}\" {Environment.NewLine}<h1>Hello world</h1>"),
-                });
-            var provider = new PageActionDescriptorProvider(
-                razorProject.Object,
-                GetAccessor<MvcOptions>(),
-                GetRazorPagesOptions());
-            var context = new ActionDescriptorProviderContext();
-
-            // Act and Assert
-            var ex = Assert.Throws<InvalidOperationException>(() => provider.OnProvidersExecuting(context));
-            Assert.Equal(
-                "The route for the page at '/Test.cshtml' cannot start with / or ~/. " +
-                "Pages do not support overriding the file path of the page.",
-                ex.Message);
         }
 
         [Fact]
-        public void GetDescriptors_WithEmptyPageDirective_MapsIndexToEmptySegment()
+        public void GetDescriptors_AddsMultipleDescriptorsForPageWithMultipleSelectors()
         {
             // Arrange
-            var razorProject = new Mock<RazorProject>();
+            var applicationModelProvider = new TestPageApplicationModelProvider(
-            razorProject.Setup(p => p.EnumerateItems("/"))
+                new PageApplicationModel("/Catalog/Details/Index.cshtml", "/Catalog/Details/Index")
-                .Returns(new[]
                 {
-                    GetProjectItem("", "/About/Index.cshtml", $"@page {Environment.NewLine}"),
+                    Selectors =
+                    {
+                         CreateSelectorModel("/Catalog/Details/Index/{id:int?}"),
+                         CreateSelectorModel("/Catalog/Details/{id:int?}"),
+                    },
                 });
+
             var provider = new PageActionDescriptorProvider(
-                razorProject.Object,
+                new[] { applicationModelProvider },
-                GetAccessor<MvcOptions>(),
-                GetRazorPagesOptions());
-            var context = new ActionDescriptorProviderContext();
-
-            // Act
-            provider.OnProvidersExecuting(context);
-
-            // Assert
-            Assert.Collection(context.Results,
-                result =>
-                {
-                    var descriptor = Assert.IsType<PageActionDescriptor>(result);
-                    Assert.Equal("/About/Index.cshtml", descriptor.RelativePath);
-                    Assert.Equal("/About/Index", descriptor.RouteValues["page"]);
-                    Assert.Equal("About/Index", descriptor.AttributeRouteInfo.Template);
-                },
-                result =>
-                {
-                    var descriptor = Assert.IsType<PageActionDescriptor>(result);
-                    Assert.Equal("/About/Index.cshtml", descriptor.RelativePath);
-                    Assert.Equal("/About/Index", descriptor.RouteValues["page"]);
-                    Assert.Equal("About", descriptor.AttributeRouteInfo.Template);
-                });
-        }
-
-        [Fact]
-        public void GetDescriptors_WithNonEmptyPageDirective_MapsIndexToEmptySegment()
-        {
-            // Arrange
-            var razorProject = new Mock<RazorProject>();
-            razorProject.Setup(p => p.EnumerateItems("/"))
-                .Returns(new[]
-                {
-                    GetProjectItem("", "/Catalog/Details/Index.cshtml", $"@page \"{{id:int?}}\" {Environment.NewLine}"),
-                });
-            var provider = new PageActionDescriptorProvider(
-                razorProject.Object,
                 GetAccessor<MvcOptions>(),
                 GetRazorPagesOptions());
             var context = new ActionDescriptorProviderContext();
@@ -253,14 +169,14 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
                     var descriptor = Assert.IsType<PageActionDescriptor>(result);
                     Assert.Equal("/Catalog/Details/Index.cshtml", descriptor.RelativePath);
                     Assert.Equal("/Catalog/Details/Index", descriptor.RouteValues["page"]);
-                    Assert.Equal("Catalog/Details/Index/{id:int?}", descriptor.AttributeRouteInfo.Template);
+                    Assert.Equal("/Catalog/Details/Index/{id:int?}", descriptor.AttributeRouteInfo.Template);
                 },
                 result =>
                 {
                     var descriptor = Assert.IsType<PageActionDescriptor>(result);
                     Assert.Equal("/Catalog/Details/Index.cshtml", descriptor.RelativePath);
                     Assert.Equal("/Catalog/Details/Index", descriptor.RouteValues["page"]);
-                    Assert.Equal("Catalog/Details/{id:int?}", descriptor.AttributeRouteInfo.Template);
+                    Assert.Equal("/Catalog/Details/{id:int?}", descriptor.AttributeRouteInfo.Template);
                 });
         }
 
@@ -269,14 +185,9 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
         {
             // Arrange
             var options = new MvcOptions();
-            var razorProject = new Mock<RazorProject>();
+            var applicationModelProvider = new TestPageApplicationModelProvider(CreateModel());
-            razorProject.Setup(p => p.EnumerateItems("/"))
-                .Returns(new[]
-                {
-                    GetProjectItem("/", "/Home.cshtml", $"@page {Environment.NewLine}"),
-                });
             var provider = new PageActionDescriptorProvider(
-                razorProject.Object,
+                new[] { applicationModelProvider },
                 GetAccessor(options),
                 GetRazorPagesOptions());
             var context = new ActionDescriptorProviderContext();
@@ -310,14 +221,9 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
             var options = new MvcOptions();
             options.Filters.Add(filter1);
             options.Filters.Add(filter2);
-            var razorProject = new Mock<RazorProject>();
+            var applicationModelProvider = new TestPageApplicationModelProvider(CreateModel());
-            razorProject.Setup(p => p.EnumerateItems("/"))
-                .Returns(new[]
-                {
-                    GetProjectItem("/", "/Home.cshtml", $"@page {Environment.NewLine}"),
-                });
             var provider = new PageActionDescriptorProvider(
-                razorProject.Object,
+                new[] { applicationModelProvider },
                 GetAccessor(options),
                 GetRazorPagesOptions());
             var context = new ActionDescriptorProviderContext();
@@ -368,15 +274,9 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
                 });
             var razorOptions = GetRazorPagesOptions();
             razorOptions.Value.Conventions.Add(convention.Object);
-
+            var applicationModelProvider = new TestPageApplicationModelProvider(CreateModel());
-            var razorProject = new Mock<RazorProject>();
-            razorProject.Setup(p => p.EnumerateItems("/"))
-                .Returns(new[]
-                {
-                    GetProjectItem("/", "/Home.cshtml", $"@page {Environment.NewLine}"),
-                });
             var provider = new PageActionDescriptorProvider(
-                razorProject.Object,
+                new[] { applicationModelProvider },
                 GetAccessor(options),
                 razorOptions);
             var context = new ActionDescriptorProviderContext();
@@ -410,6 +310,23 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
                 });
         }
 
+        private static PageApplicationModel CreateModel()
+        {
+            return new PageApplicationModel("/Home.cshtml", "/Home")
+            {
+                Selectors =
+                {
+                    new SelectorModel
+                    {
+                        AttributeRouteModel = new AttributeRouteModel
+                        {
+                            Template = "Home",
+                        }
+                    }
+                }
+            };
+        }
+
         private static IOptions<TOptions> GetAccessor<TOptions>(TOptions options = null)
             where TOptions : class, new()
         {
@@ -432,5 +349,30 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
 
             return new DefaultRazorProjectItem(testFileInfo, basePath, path);
         }
+
+        private class TestPageApplicationModelProvider : IPageApplicationModelProvider
+        {
+            private readonly PageApplicationModel[] _models;
+
+            public TestPageApplicationModelProvider(params PageApplicationModel[] models)
+            {
+                _models = models ?? Array.Empty<PageApplicationModel>();
+            }
+
+            public int Order => 0;
+
+            public void OnProvidersExecuted(PageApplicationModelProviderContext context)
+            {
+            }
+
+            public void OnProvidersExecuting(PageApplicationModelProviderContext context)
+            {
+                foreach (var model in _models)
+                {
+                    context.Results.Add(model);
+                }
+
+            }
+        }
     }
 }

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

@@ -0,0 +1,113 @@
+// 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.ApplicationModels;
+using Microsoft.AspNetCore.Mvc.ApplicationParts;
+using Xunit;
+
+namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
+{
+    public class CompiledPageApplicationModelProviderTest
+    {
+        [Fact]
+        public void OnProvidersExecuting_AddsModelsForCompiledViews()
+        {
+            // Arrange
+            var info = new[]
+            {
+                new CompiledPageInfo("/Pages/About.cshtml", typeof(object), routePrefix: string.Empty),
+                new CompiledPageInfo("/Pages/Home.cshtml", typeof(object), "some-prefix"),
+            };
+            var provider = new TestCompiledPageApplicationModelProvider(info, new RazorPagesOptions());
+            var context = new PageApplicationModelProviderContext();
+
+            // Act
+            provider.OnProvidersExecuting(context);
+
+            // Assert
+            Assert.Collection(context.Results,
+                result =>
+                {
+                    Assert.Equal("/Pages/About.cshtml", result.RelativePath);
+                    Assert.Equal("/Pages/About", result.ViewEnginePath);
+                    Assert.Collection(result.Selectors,
+                        selector => Assert.Equal("Pages/About", selector.AttributeRouteModel.Template));
+                },
+                result =>
+                {
+                    Assert.Equal("/Pages/Home.cshtml", result.RelativePath);
+                    Assert.Equal("/Pages/Home", result.ViewEnginePath);
+                    Assert.Collection(result.Selectors,
+                        selector => Assert.Equal("Pages/Home/some-prefix", selector.AttributeRouteModel.Template));
+                });
+        }
+
+        [Fact]
+        public void OnProvidersExecuting_AddsMultipleSelectorsForIndexPage()
+        {
+            // Arrange
+            var info = new[]
+            {
+                new CompiledPageInfo("/Pages/Index.cshtml", typeof(object), routePrefix: string.Empty),
+                new CompiledPageInfo("/Pages/Admin/Index.cshtml", typeof(object), "some-template"),
+            };
+            var provider = new TestCompiledPageApplicationModelProvider(info, new RazorPagesOptions());
+            var context = new PageApplicationModelProviderContext();
+
+            // Act
+            provider.OnProvidersExecuting(context);
+
+            // Assert
+            Assert.Collection(context.Results,
+                result =>
+                {
+                    Assert.Equal("/Pages/Index.cshtml", result.RelativePath);
+                    Assert.Equal("/Pages/Index", result.ViewEnginePath);
+                    Assert.Collection(result.Selectors,
+                        selector => Assert.Equal("Pages/Index", selector.AttributeRouteModel.Template),
+                        selector => Assert.Equal("Pages", selector.AttributeRouteModel.Template));
+                },
+                result =>
+                {
+                    Assert.Equal("/Pages/Admin/Index.cshtml", result.RelativePath);
+                    Assert.Equal("/Pages/Admin/Index", result.ViewEnginePath);
+                    Assert.Collection(result.Selectors,
+                        selector => Assert.Equal("Pages/Admin/Index/some-template", selector.AttributeRouteModel.Template),
+                        selector => Assert.Equal("Pages/Admin/some-template", selector.AttributeRouteModel.Template));
+                });
+        }
+
+        [Fact]
+        public void OnProvidersExecuting_ThrowsIfRouteTemplateHasOverridePattern()
+        {
+            // Arrange
+            var info = new[]
+            {
+                new CompiledPageInfo("/Pages/Index.cshtml", typeof(object), routePrefix: string.Empty),
+                new CompiledPageInfo("/Pages/Home.cshtml", typeof(object), "/some-prefix"),
+            };
+            var provider = new TestCompiledPageApplicationModelProvider(info, new RazorPagesOptions());
+            var context = new PageApplicationModelProviderContext();
+
+            // Act & Assert
+            var ex = Assert.Throws<InvalidOperationException>(() => provider.OnProvidersExecuting(context));
+            Assert.Equal("The route for the page at '/Pages/Home.cshtml' cannot start with / or ~/. Pages do not support overriding the file path of the page.",
+                ex.Message);
+        }
+
+        public class TestCompiledPageApplicationModelProvider : CompiledPageApplicationModelProvider
+        {
+            private readonly IEnumerable<CompiledPageInfo> _info;
+
+            public TestCompiledPageApplicationModelProvider(IEnumerable<CompiledPageInfo> info, RazorPagesOptions options)
+                : base(new ApplicationPartManager(), new TestOptionsManager<RazorPagesOptions>(options))
+            {
+                _info = info;
+            }
+
+            protected override IEnumerable<CompiledPageInfo> GetCompiledPages() => _info;
+        }
+    }
+}

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

@@ -723,8 +723,10 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
         }
 
         [Fact]
-        public void GetViewStartFactories_NoFactoriesForMissingFiles()
+        public void GetViewStartFactories_ReturnsFactoriesForFilesThatDoNotExistInProject()
         {
+            // The factory provider might have access to _ViewStarts for files that do not exist on disk \ RazorProject.
+            // This test verifies that we query the factory provider correctly.
             // Arrange
             var descriptor = new PageActionDescriptor()
             {
@@ -739,6 +741,14 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
             var actionDescriptorProvider = new Mock<IActionDescriptorCollectionProvider>();
             actionDescriptorProvider.Setup(p => p.ActionDescriptors).Returns(descriptorCollection);
 
+            var pageFactory = new Mock<IRazorPageFactoryProvider>();
+            pageFactory.Setup(f => f.CreateFactory("/Views/Deeper/_ViewStart.cshtml"))
+                .Returns(new RazorPageFactoryResult(() => null, new IChangeToken[0]));
+            pageFactory.Setup(f => f.CreateFactory("/Views/_ViewStart.cshtml"))
+                .Returns(new RazorPageFactoryResult(new IChangeToken[0]));
+            pageFactory.Setup(f => f.CreateFactory("/_ViewStart.cshtml"))
+                .Returns(new RazorPageFactoryResult(() => null, new IChangeToken[0]));
+
             // No files
             var fileProvider = new TestFileProvider();
             var razorProject = new TestRazorProject(fileProvider);
@@ -748,16 +758,16 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
                 actionDescriptorProvider.Object,
                 pageProvider: null,
                 modelProvider: null,
-                razorPageFactoryProvider: CreateRazorPageFactoryProvider(),
+                razorPageFactoryProvider: pageFactory.Object,
                 razorProject: razorProject);
 
             var compiledDescriptor = CreateCompiledPageActionDescriptor(descriptor);
 
             // Act
-            var factories = invokerProvider.GetViewStartFactories(compiledDescriptor);
+            var factories = invokerProvider.GetViewStartFactories(compiledDescriptor).ToList();
 
             // Assert
-            Assert.Empty(factories);
+            Assert.Equal(2, factories.Count);
         }
 
         private IRazorPageFactoryProvider CreateRazorPageFactoryProvider()

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

@@ -0,0 +1,179 @@
+// 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.Razor;
+using Microsoft.Extensions.FileProviders;
+using Xunit;
+
+namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
+{
+    public class RazorProjectPageApplicationModelProviderTest
+    {
+        [Fact]
+        public void OnProvidersExecuting_ReturnsPagesWithPageDirective()
+        {
+            // Arrange
+            var fileProvider = new TestFileProvider();
+            var file1 = fileProvider.AddFile("/Pages/Home.cshtml", "@page");
+            var file2 = fileProvider.AddFile("/Pages/Test.cshtml", "Hello world");
+
+            var dir1 = fileProvider.AddDirectoryContent("/Pages", new IFileInfo[] { file1, file2 });
+            fileProvider.AddDirectoryContent("/", new[] { dir1 });
+
+            var project = new TestRazorProject(fileProvider);
+
+            var optionsManager = new TestOptionsManager<RazorPagesOptions>();
+            optionsManager.Value.RootDirectory = "/";
+            var provider = new RazorProjectPageApplicationModelProvider(project, optionsManager);
+            var context = new PageApplicationModelProviderContext();
+
+            // Act
+            provider.OnProvidersExecuting(context);
+
+            // Assert
+            Assert.Collection(context.Results,
+                model =>
+                {
+                    Assert.Equal("/Pages/Home.cshtml", model.RelativePath);
+                    Assert.Equal("/Pages/Home", model.ViewEnginePath);
+                    Assert.Collection(model.Selectors,
+                        selector => Assert.Equal("Pages/Home", selector.AttributeRouteModel.Template));
+                });
+        }
+
+        [Fact]
+        public void OnProvidersExecuting_AddsMultipleSelectorsForIndexPages()
+        {
+            // Arrange
+            var fileProvider = new TestFileProvider();
+            var file1 = fileProvider.AddFile("/Pages/Index.cshtml", "@page");
+            var file2 = fileProvider.AddFile("/Pages/Test.cshtml", "Hello world");
+            var file3 = fileProvider.AddFile("/Pages/Admin/Index.cshtml", "@page \"test\"");
+
+            var dir2 = fileProvider.AddDirectoryContent("/Pages/Admin", new[] { file3 });
+            var dir1 = fileProvider.AddDirectoryContent("/Pages", new IFileInfo[] { dir2, file1, file2 });
+            fileProvider.AddDirectoryContent("/", new[] { dir1 });
+
+            var project = new TestRazorProject(fileProvider);
+
+            var optionsManager = new TestOptionsManager<RazorPagesOptions>();
+            optionsManager.Value.RootDirectory = "/";
+            var provider = new RazorProjectPageApplicationModelProvider(project, optionsManager);
+            var context = new PageApplicationModelProviderContext();
+
+            // Act
+            provider.OnProvidersExecuting(context);
+
+            // Assert
+            Assert.Collection(context.Results,
+                model =>
+                {
+                    Assert.Equal("/Pages/Admin/Index.cshtml", model.RelativePath);
+                    Assert.Equal("/Pages/Admin/Index", model.ViewEnginePath);
+                    Assert.Collection(model.Selectors,
+                        selector => Assert.Equal("Pages/Admin/Index/test", selector.AttributeRouteModel.Template),
+                        selector => Assert.Equal("Pages/Admin/test", selector.AttributeRouteModel.Template));
+                },
+                model =>
+                {
+                    Assert.Equal("/Pages/Index.cshtml", model.RelativePath);
+                    Assert.Equal("/Pages/Index", model.ViewEnginePath);
+                    Assert.Collection(model.Selectors,
+                        selector => Assert.Equal("Pages/Index", selector.AttributeRouteModel.Template),
+                        selector => Assert.Equal("Pages", selector.AttributeRouteModel.Template));
+                });
+        }
+
+        [Fact]
+        public void OnProvidersExecuting_ThrowsIfRouteTemplateHasOverridePattern()
+        {
+            // Arrange
+            var fileProvider = new TestFileProvider();
+            var file = fileProvider.AddFile("/Index.cshtml", "@page \"/custom-route\"");
+            fileProvider.AddDirectoryContent("/", new[] { file });
+
+            var project = new TestRazorProject(fileProvider);
+
+            var optionsManager = new TestOptionsManager<RazorPagesOptions>();
+            optionsManager.Value.RootDirectory = "/";
+            var provider = new RazorProjectPageApplicationModelProvider(project, optionsManager);
+            var context = new PageApplicationModelProviderContext();
+
+            // Act & Assert
+            var ex = Assert.Throws<InvalidOperationException>(() => provider.OnProvidersExecuting(context));
+            Assert.Equal("The route for the page at '/Index.cshtml' cannot start with / or ~/. Pages do not support overriding the file path of the page.", 
+                ex.Message);
+        }
+
+        [Fact]
+        public void OnProvidersExecuting_SkipsPagesStartingWithUnderscore()
+        {
+            // Arrange
+            var fileProvider = new TestFileProvider();
+            var dir1 = fileProvider.AddDirectoryContent("/Pages",
+                new[]
+                {
+                    fileProvider.AddFile("/Pages/Home.cshtml", "@page"),
+                    fileProvider.AddFile("/Pages/_Layout.cshtml", "@page")
+                });
+            fileProvider.AddDirectoryContent("/", new[] { dir1 });
+
+            var project = new TestRazorProject(fileProvider);
+
+            var optionsManager = new TestOptionsManager<RazorPagesOptions>();
+            optionsManager.Value.RootDirectory = "/";
+            var provider = new RazorProjectPageApplicationModelProvider(project, optionsManager);
+            var context = new PageApplicationModelProviderContext();
+
+            // Act
+            provider.OnProvidersExecuting(context);
+
+            // Assert
+            Assert.Collection(context.Results,
+                model =>
+                {
+                    Assert.Equal("/Pages/Home.cshtml", model.RelativePath);
+                });
+        }
+
+        [Fact]
+        public void OnProvidersExecuting_DiscoversFilesUnderBasePath()
+        {
+            // Arrange
+            var fileProvider = new TestFileProvider();
+            var dir1 = fileProvider.AddDirectoryContent("/Pages",
+                new[]
+                {
+                    fileProvider.AddFile("/Pages/Index.cshtml", "@page"),
+                    fileProvider.AddFile("/Pages/_Layout.cshtml", "@page")
+                });
+            var dir2 = fileProvider.AddDirectoryContent("/NotPages",
+                new[]
+                {
+                    fileProvider.AddFile("/NotPages/Index.cshtml", "@page"),
+                    fileProvider.AddFile("/NotPages/_Layout.cshtml", "@page")
+                });
+            var rootFile = fileProvider.AddFile("/Index.cshtml", "@page");
+            fileProvider.AddDirectoryContent("/", new IFileInfo[] { rootFile, dir1, dir2 });
+
+            var project = new TestRazorProject(fileProvider);
+
+            var optionsManager = new TestOptionsManager<RazorPagesOptions>();
+            optionsManager.Value.RootDirectory = "/Pages";
+            var provider = new RazorProjectPageApplicationModelProvider(project, optionsManager);
+            var context = new PageApplicationModelProviderContext();
+
+            // Act
+            provider.OnProvidersExecuting(context);
+
+            // Assert
+            Assert.Collection(context.Results,
+                model =>
+                {
+                    Assert.Equal("/Pages/Index.cshtml", model.RelativePath);
+                });
+        }
+    }
+}

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

@@ -213,7 +213,8 @@ namespace Microsoft.AspNetCore.Mvc
                 feature => Assert.IsType<ControllerFeatureProvider>(feature),
                 feature => Assert.IsType<ViewComponentFeatureProvider>(feature),
                 feature => Assert.IsType<MetadataReferenceFeatureProvider>(feature),
-                feature => Assert.IsType<ViewsFeatureProvider>(feature));
+                feature => Assert.IsType<ViewsFeatureProvider>(feature),
+                feature => Assert.IsType<CompiledPageFeatureProvider>(feature));
         }
 
         [Fact]
@@ -419,6 +420,14 @@ namespace Microsoft.AspNetCore.Mvc
                             typeof(JsonPatchOperationsArrayProvider),
                         }
                     },
+                    {
+                        typeof(IPageApplicationModelProvider),
+                        new[]
+                        {
+                            typeof(CompiledPageApplicationModelProvider),
+                            typeof(RazorProjectPageApplicationModelProvider),
+                        }
+                    },
                 };
             }
         }

test/Microsoft.AspNetCore.Mvc.TestCommon/TestDirectoryContent.cs

@@ -1,23 +1,41 @@
 // 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;
 using System.Collections.Generic;
+using System.IO;
 using Microsoft.Extensions.FileProviders;
 
 namespace Microsoft.AspNetCore.Mvc.TestCommon
 {
-    public class TestDirectoryContent : IDirectoryContents
+    public class TestDirectoryContent : IDirectoryContents, IFileInfo
     {
         private readonly IEnumerable<IFileInfo> _files;
 
-        public TestDirectoryContent(IEnumerable<IFileInfo> files)
+        public TestDirectoryContent(string name, IEnumerable<IFileInfo> files)
         {
+            Name = name;
             _files = files;
         }
 
         public bool Exists => true;
 
+        public long Length => throw new NotSupportedException();
+
+        public string PhysicalPath => throw new NotSupportedException();
+
+        public string Name { get; }
+
+        public DateTimeOffset LastModified => throw new NotSupportedException();
+
+        public bool IsDirectory => true;
+
+        public Stream CreateReadStream()
+        {
+            throw new NotSupportedException();
+        }
+
         public IEnumerator<IFileInfo> GetEnumerator() => _files.GetEnumerator();
 
         IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();

test/Microsoft.AspNetCore.Mvc.TestCommon/TestFileProvider.cs

@@ -47,7 +47,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor
 
         public TestDirectoryContent AddDirectoryContent(string path, IEnumerable<IFileInfo> files)
         {
-            var directoryContent = new TestDirectoryContent(files);
+            var directoryContent = new TestDirectoryContent(Path.GetFileName(path), files);
             _directoryContentsLookup[path] = directoryContent;
             return directoryContent;
         }