Per-page opt out from interactive routing (#55157)

Author: SteveSandersonMS

src/Components/Components/src/PublicAPI.Unshipped.txt

@@ -1 +1,3 @@
 #nullable enable
+Microsoft.AspNetCore.Components.ExcludeFromInteractiveRoutingAttribute
+Microsoft.AspNetCore.Components.ExcludeFromInteractiveRoutingAttribute.ExcludeFromInteractiveRoutingAttribute() -> void

src/Components/Components/src/Routing/ExcludeFromInteractiveRoutingAttribute.cs

@@ -0,0 +1,16 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using Microsoft.AspNetCore.Components.Routing;
+
+namespace Microsoft.AspNetCore.Components;
+
+/// <summary>
+/// When applied to a page component, indicates that the interactive <see cref="Router"/> component should
+/// ignore that page. This means that navigations to the page will not be resolved by interactive routing,
+/// but instead will cause a full page reload.
+/// </summary>
+[AttributeUsage(AttributeTargets.Class, AllowMultiple = false)]
+public sealed class ExcludeFromInteractiveRoutingAttribute : Attribute
+{
+}

src/Components/Components/src/Routing/RouteTableFactory.cs

@@ -73,7 +73,9 @@ static void GetRouteableComponents(List<Type> routeableComponents, Assembly asse
         {
             foreach (var type in assembly.ExportedTypes)
             {
-                if (typeof(IComponent).IsAssignableFrom(type) && type.IsDefined(typeof(RouteAttribute)))
+                if (typeof(IComponent).IsAssignableFrom(type)
+                    && type.IsDefined(typeof(RouteAttribute))
+                    && !type.IsDefined(typeof(ExcludeFromInteractiveRoutingAttribute)))
                 {
                     routeableComponents.Add(type);
                 }

src/Components/Components/test/Routing/RouteTableFactoryTests.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Globalization;
+using System.Reflection;
 using Microsoft.AspNetCore.Routing.Patterns;
 using Microsoft.AspNetCore.Routing.Tree;
 using Microsoft.Extensions.DependencyInjection;
@@ -74,6 +75,20 @@ public void IgnoresIdenticalTypes()
         Assert.Equal(routes.GroupBy(x => x.Handler).Count(), routes.Count);
     }
 
+    [Fact]
+    public void RespectsExcludeFromInteractiveRoutingAttribute()
+    {
+        // Arrange & Act
+        var routeTableFactory = new RouteTableFactory();
+        var routeTable = routeTableFactory.Create(new RouteKey(GetType().Assembly, Array.Empty<Assembly>()), _serviceProvider);
+
+        var routes = GetRoutes(routeTable);
+
+        // Assert
+        Assert.Contains(routes, r => r.Handler == typeof(ComponentWithoutExcludeFromInteractiveRoutingAttribute));
+        Assert.DoesNotContain(routes, r => r.Handler == typeof(ComponentWithExcludeFromInteractiveRoutingAttribute));
+    }
+
     [Fact]
     public void CanDiscoverRoute()
     {
@@ -1120,4 +1135,11 @@ public RouteTable Build()
 
     class TestHandler1 { }
     class TestHandler2 { }
+
+    [Route("/ComponentWithoutExcludeFromInteractiveRoutingAttribute")]
+    public class ComponentWithoutExcludeFromInteractiveRoutingAttribute : ComponentBase { }
+
+    [Route("/ComponentWithExcludeFromInteractiveRoutingAttribute")]
+    [ExcludeFromInteractiveRouting]
+    public class ComponentWithExcludeFromInteractiveRoutingAttribute : ComponentBase { }
 }

src/Components/Endpoints/src/Builder/RazorComponentsEndpointHttpContextExtensions.cs

@@ -0,0 +1,49 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Collections.Concurrent;
+using System.Reflection;
+using System.Reflection.Metadata;
+using Microsoft.AspNetCore.Components.Endpoints;
+using Microsoft.AspNetCore.Components.Routing;
+using Microsoft.AspNetCore.Http;
+
+[assembly: MetadataUpdateHandler(typeof(RazorComponentsEndpointHttpContextExtensions.MetadataUpdateHandler))]
+
+namespace Microsoft.AspNetCore.Components.Routing;
+
+/// <summary>
+/// Extensions to <see cref="HttpContext"/> for Razor component applications.
+/// </summary>
+public static class RazorComponentsEndpointHttpContextExtensions
+{
+    private static readonly ConcurrentDictionary<Type, bool> AcceptsInteractiveRoutingCache = new();
+
+    /// <summary>
+    /// Determines whether the current endpoint is a Razor component that can be reached through
+    /// interactive routing. This is true for all page components except if they declare the
+    /// attribute <see cref="ExcludeFromInteractiveRoutingAttribute"/>.
+    /// </summary>
+    /// <param name="context">The <see cref="HttpContext"/>.</param>
+    /// <returns>True if the current endpoint is a Razor component that does not declare <see cref="ExcludeFromInteractiveRoutingAttribute"/>.</returns>
+    public static bool AcceptsInteractiveRouting(this HttpContext context)
+    {
+        ArgumentNullException.ThrowIfNull(context);
+
+        var pageType = context.GetEndpoint()?.Metadata.GetMetadata<ComponentTypeMetadata>()?.Type;
+
+        return pageType is not null
+            && AcceptsInteractiveRoutingCache.GetOrAdd(
+                pageType,
+                static pageType => !pageType.IsDefined(typeof(ExcludeFromInteractiveRoutingAttribute)));
+    }
+
+    internal static class MetadataUpdateHandler
+    {
+        /// <summary>
+        /// Invoked as part of <see cref="MetadataUpdateHandlerAttribute" /> contract for hot reload.
+        /// </summary>
+        public static void ClearCache(Type[]? _)
+            => AcceptsInteractiveRoutingCache.Clear();
+    }
+}

src/Components/Endpoints/src/PublicAPI.Unshipped.txt

@@ -1 +1,3 @@
 #nullable enable
+Microsoft.AspNetCore.Components.Routing.RazorComponentsEndpointHttpContextExtensions
+static Microsoft.AspNetCore.Components.Routing.RazorComponentsEndpointHttpContextExtensions.AcceptsInteractiveRouting(this Microsoft.AspNetCore.Http.HttpContext! context) -> bool

src/Components/Samples/BlazorUnitedApp/App.razor

@@ -9,33 +9,10 @@
     <link rel="stylesheet" href="css/site.css" />
     <link href="BlazorUnitedApp.styles.css" rel="stylesheet" />
     <link rel="icon" type="image/png" href="favicon.png" />
-    <HeadOutlet></HeadOutlet>
+    <HeadOutlet />
 </head>
 <body>
-    <Router AppAssembly="@typeof(App).Assembly">
-        <Found Context="routeData">
-            <RouteView RouteData="@routeData" DefaultLayout="@typeof(MainLayout)" />
-            <FocusOnNavigate RouteData="@routeData" Selector="h1" />
-        </Found>
-        <NotFound>
-            <PageTitle>Not found</PageTitle>
-            <LayoutView Layout="@typeof(MainLayout)">
-                <p role="alert">Sorry, there's nothing at this address.</p>
-            </LayoutView>
-        </NotFound>
-    </Router>
-
-    <div id="blazor-error-ui">
-        <environment include="Staging,Production">
-            An error has occurred. This application may no longer respond until reloaded.
-        </environment>
-        <environment include="Development">
-            An unhandled exception has occurred. See browser dev tools for details.
-        </environment>
-        <a href="" class="reload">Reload</a>
-        <a class="dismiss">🗙</a>
-    </div>
-
+    <Routes />
     <script src="_framework/blazor.web.js" suppress-error="BL9992"></script>
 </body>
 </html>

src/Components/Samples/BlazorUnitedApp/Pages/Counter.razor

@@ -1,4 +1,5 @@
 @page "/counter"
+@rendermode InteractiveServer
 <PageTitle>Counter</PageTitle>
 
 <h1>Counter</h1>

src/Components/Samples/BlazorUnitedApp/Program.cs

@@ -7,7 +7,8 @@
 var builder = WebApplication.CreateBuilder(args);
 
 // Add services to the container.
-builder.Services.AddRazorComponents();
+builder.Services.AddRazorComponents()
+    .AddInteractiveServerComponents();
 
 builder.Services.AddSingleton<WeatherForecastService>();
 
@@ -26,6 +27,7 @@
 app.UseStaticFiles();
 app.UseAntiforgery();
 
-app.MapRazorComponents<App>();
+app.MapRazorComponents<App>()
+    .AddInteractiveServerRenderMode();
 
 app.Run();

src/Components/Samples/BlazorUnitedApp/Routes.razor

@@ -0,0 +1,12 @@
+<Router AppAssembly="@typeof(App).Assembly">
+    <Found Context="routeData">
+        <RouteView RouteData="@routeData" DefaultLayout="@typeof(MainLayout)" />
+        <FocusOnNavigate RouteData="@routeData" Selector="h1" />
+    </Found>
+    <NotFound>
+        <PageTitle>Not found</PageTitle>
+        <LayoutView Layout="@typeof(MainLayout)">
+            <p role="alert">Sorry, there's nothing at this address.</p>
+        </LayoutView>
+    </NotFound>
+</Router>