Add NotFound method in NavigationManager for interactive and static rendering

src/Components/Components/src/NavigationManager.cs

@@ -35,6 +35,25 @@ public event EventHandler<LocationChangedEventArgs> LocationChanged
 
     private CancellationTokenSource? _locationChangingCts;
 
+    /// <summary>
+    /// An event that fires when the page is not found.
+    /// </summary>
+    public event EventHandler<EventArgs> NotFoundEvent
+    {
+        add
+        {
+            AssertInitialized();
+            _notFound += value;
+        }
+        remove
+        {
+            AssertInitialized();
+            _notFound -= value;
+        }
+    }
+
+    private EventHandler<EventArgs>? _notFound;
+
     // For the baseUri it's worth storing as a System.Uri so we can do operations
     // on that type. System.Uri gives us access to the original string anyway.
     private Uri? _baseUri;
@@ -177,6 +196,16 @@ protected virtual void NavigateToCore([StringSyntax(StringSyntaxAttribute.Uri)]
     public virtual void Refresh(bool forceReload = false)
         => NavigateTo(Uri, forceLoad: true, replace: true);
 
+    /// <summary>
+    /// Handles setting the NotFound state.
+    /// </summary>
+    public virtual void NotFound() => NotFoundCore();
+
+    private void NotFoundCore()
+    {
+        _notFound?.Invoke(this, new EventArgs());
+    }
+
     /// <summary>
     /// Called to initialize BaseURI and current URI before these values are used for the first time.
     /// Override <see cref="EnsureInitialized" /> and call this method to dynamically calculate these values.

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

@@ -1,4 +1,6 @@
 #nullable enable
+Microsoft.AspNetCore.Components.NavigationManager.NotFoundEvent -> System.EventHandler<System.EventArgs!>!
+virtual Microsoft.AspNetCore.Components.NavigationManager.NotFound() -> void
 Microsoft.AspNetCore.Components.Infrastructure.ComponentStatePersistenceManager.ComponentStatePersistenceManager(Microsoft.Extensions.Logging.ILogger<Microsoft.AspNetCore.Components.Infrastructure.ComponentStatePersistenceManager!>! logger, System.IServiceProvider! serviceProvider) -> void
 Microsoft.AspNetCore.Components.Infrastructure.ComponentStatePersistenceManager.SetPlatformRenderMode(Microsoft.AspNetCore.Components.IComponentRenderMode! renderMode) -> void
 Microsoft.AspNetCore.Components.Infrastructure.RegisterPersistentComponentStateServiceCollectionExtensions

src/Components/Components/src/Routing/Router.cs

@@ -105,6 +105,7 @@ public void Attach(RenderHandle renderHandle)
         _baseUri = NavigationManager.BaseUri;
         _locationAbsolute = NavigationManager.Uri;
         NavigationManager.LocationChanged += OnLocationChanged;
+        NavigationManager.NotFoundEvent += OnNotFound;
         RoutingStateProvider = ServiceProvider.GetService<IRoutingStateProvider>();
 
         if (HotReloadManager.Default.MetadataUpdateSupported)
@@ -146,6 +147,7 @@ public async Task SetParametersAsync(ParameterView parameters)
     public void Dispose()
     {
         NavigationManager.LocationChanged -= OnLocationChanged;
+        NavigationManager.NotFoundEvent -= OnNotFound;
         if (HotReloadManager.Default.MetadataUpdateSupported)
         {
             HotReloadManager.Default.OnDeltaApplied -= ClearRouteCaches;
@@ -320,6 +322,15 @@ private void OnLocationChanged(object sender, LocationChangedEventArgs args)
         }
     }
 
+    private void OnNotFound(object sender, EventArgs args)
+    {
+        if (_renderHandle.IsInitialized)
+        {
+            Log.DisplayingNotFound(_logger);
+            _renderHandle.Render(NotFound ?? DefaultNotFoundContent);
+        }
+    }
+
     async Task IHandleAfterRender.OnAfterRenderAsync()
     {
         if (!_navigationInterceptionEnabled)
@@ -345,5 +356,8 @@ private static partial class Log
 
         [LoggerMessage(3, LogLevel.Debug, "Navigating to non-component URI '{ExternalUri}' in response to path '{Path}' with base URI '{BaseUri}'", EventName = "NavigatingToExternalUri")]
         internal static partial void NavigatingToExternalUri(ILogger logger, string externalUri, string path, string baseUri);
+
+        [LoggerMessage(4, LogLevel.Debug, $"Displaying {nameof(NotFound)} on request", EventName = "DisplayingNotFoundOnRequest")]
+        internal static partial void DisplayingNotFound(ILogger logger);
     }
 }

src/Components/Endpoints/src/RazorComponentEndpointInvoker.cs

@@ -74,7 +74,7 @@ private async Task RenderComponentCore(HttpContext context)
             return Task.CompletedTask;
         });
 
-        await EndpointHtmlRenderer.InitializeStandardComponentServicesAsync(
+        await _renderer.InitializeStandardComponentServicesAsync(
             context,
             componentType: pageComponent,
             handler: result.HandlerName,

src/Components/Endpoints/src/Rendering/EndpointHtmlRenderer.EventDispatch.cs

@@ -74,6 +74,16 @@ private Task ReturnErrorResponse(string detailedMessage)
             : Task.CompletedTask;
     }
 
+    private void SetNotFoundResponse(object? sender, EventArgs args)
+    {
+        if (_httpContext.Response.HasStarted)
+        {
+            throw new InvalidOperationException("Cannot set a NotFound response after the response has already started.");
+        }
+        _httpContext.Response.StatusCode = StatusCodes.Status404NotFound;
+        SignalRendererToFinishRendering();
+    }
+
     private void UpdateNamedSubmitEvents(in RenderBatch renderBatch)
     {
         if (renderBatch.NamedEventChanges is { } changes)

src/Components/Endpoints/src/Rendering/EndpointHtmlRenderer.cs

@@ -43,6 +43,7 @@ internal partial class EndpointHtmlRenderer : StaticHtmlRenderer, IComponentPrer
     private Task? _servicesInitializedTask;
     private HttpContext _httpContext = default!; // Always set at the start of an inbound call
     private ResourceAssetCollection? _resourceCollection;
+    private bool _rendererIsStopped;
 
     // The underlying Renderer always tracks the pending tasks representing *full* quiescence, i.e.,
     // when everything (regardless of streaming SSR) is fully complete. In this subclass we also track
@@ -71,14 +72,19 @@ private void SetHttpContext(HttpContext httpContext)
         }
     }
 
-    internal static async Task InitializeStandardComponentServicesAsync(
+    internal async Task InitializeStandardComponentServicesAsync(
         HttpContext httpContext,
         [DynamicallyAccessedMembers(Component)] Type? componentType = null,
         string? handler = null,
         IFormCollection? form = null)
     {
-        var navigationManager = (IHostEnvironmentNavigationManager)httpContext.RequestServices.GetRequiredService<NavigationManager>();
-        navigationManager?.Initialize(GetContextBaseUri(httpContext.Request), GetFullUri(httpContext.Request));
+        var navigationManager = httpContext.RequestServices.GetRequiredService<NavigationManager>();
+        ((IHostEnvironmentNavigationManager)navigationManager)?.Initialize(GetContextBaseUri(httpContext.Request), GetFullUri(httpContext.Request));
+
+        if (navigationManager != null)
+        {
+            navigationManager.NotFoundEvent += SetNotFoundResponse;
+        }
 
         var authenticationStateProvider = httpContext.RequestServices.GetService<AuthenticationStateProvider>();
         if (authenticationStateProvider is IHostEnvironmentAuthenticationStateProvider hostEnvironmentAuthenticationStateProvider)
@@ -170,14 +176,31 @@ protected override void AddPendingTask(ComponentState? componentState, Task task
         base.AddPendingTask(componentState, task);
     }
 
+    private void SignalRendererToFinishRendering()
+    {
+        _rendererIsStopped = true;
+    }
+
+    protected override void ProcessPendingRender()
+    {
+        if (_rendererIsStopped)
+        {
+            // When the application triggers a NotFound event, we continue rendering the current batch.
+            // However, after completing this batch, we do not want to process any further UI updates,
+            // as we are going to return a 404 status and discard the UI updates generated so far.
+            return;
+        }
+        base.ProcessPendingRender();
+    }
+
     // For tests only
     internal Task? NonStreamingPendingTasksCompletion;
 
     protected override Task UpdateDisplayAsync(in RenderBatch renderBatch)
     {
         UpdateNamedSubmitEvents(in renderBatch);
 
-        if (_streamingUpdatesWriter is { } writer)
+        if (_streamingUpdatesWriter is { } writer && !_rendererIsStopped)
         {
             // Important: SendBatchAsStreamingUpdate *must* be invoked synchronously
             // before any 'await' in this method. That's enforced by the compiler

src/Components/Server/src/Circuits/RemoteNavigationManager.cs

@@ -197,6 +197,9 @@ public static void RequestingNavigation(ILogger logger, string uri, NavigationOp
         [LoggerMessage(5, LogLevel.Error, "Failed to refresh", EventName = "RefreshFailed")]
         public static partial void RefreshFailed(ILogger logger, Exception exception);
 
+        [LoggerMessage(1, LogLevel.Debug, "Requesting not found", EventName = "RequestingNotFound")]
+        public static partial void RequestingNotFound(ILogger logger);
+
         [LoggerMessage(6, LogLevel.Debug, "Navigation completed when changing the location to {Uri}", EventName = "NavigationCompleted")]
         public static partial void NavigationCompleted(ILogger logger, string uri);
 

src/Components/test/E2ETest/ServerRenderingTests/NoInteractivityTest.cs

@@ -1,6 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Net.Http;
 using Components.TestServer.RazorComponents;
 using Microsoft.AspNetCore.Components.E2ETest.Infrastructure;
 using Microsoft.AspNetCore.Components.E2ETest.Infrastructure.ServerFixtures;

src/Components/test/E2ETest/Tests/GlobalInteractivityTest.cs

@@ -1,7 +1,10 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Net;
+using System.Net.Http;
 using Components.TestServer.RazorComponents;
+using Microsoft.AspNetCore.Components.E2ETest;
 using Microsoft.AspNetCore.Components.E2ETest.Infrastructure;
 using Microsoft.AspNetCore.Components.E2ETest.Infrastructure.ServerFixtures;
 using Microsoft.AspNetCore.E2ETesting;
@@ -17,6 +20,40 @@ public class GlobalInteractivityTest(
     ITestOutputHelper output)
     : ServerTestBase<BasicTestAppServerSiteFixture<RazorComponentEndpointsStartup<GlobalInteractivityApp>>>(browserFixture, serverFixture, output)
 {
+
+    [Theory]
+    [InlineData("server", true)]
+    [InlineData("webassembly", true)]
+    [InlineData("ssr", false)]
+    public void CanRenderNotFoundInteractive(string renderingMode, bool isInteractive)
+    {
+        Navigate($"/subdir/render-not-found-{renderingMode}");
+
+        if (isInteractive)
+        {
+            var buttonId = "trigger-not-found";
+            Browser.WaitForElementToBeVisible(By.Id(buttonId));
+            Browser.Exists(By.Id(buttonId)).Click();
+        }
+
+        var bodyText = Browser.FindElement(By.TagName("body")).Text;
+        Assert.Contains("There's nothing here", bodyText);
+    }
+
+    [Fact]
+    public async Task CanSetNotFoundStatus()
+    {
+        var statusCode = await GetStatusCodeAsync($"/subdir/render-not-found-ssr");
+        Assert.Equal(HttpStatusCode.NotFound, statusCode);
+    }
+
+    private async Task<HttpStatusCode> GetStatusCodeAsync(string relativeUrl)
+    {
+        using var client = new HttpClient() { BaseAddress = _serverFixture.RootUri };
+        var response = await client.GetAsync(relativeUrl, HttpCompletionOption.ResponseHeadersRead);
+        return response.StatusCode;
+    }
+
     [Fact]
     public void CanFindStaticallyRenderedPageAfterClickingBrowserBackButtonOnDynamicallyRenderedPage()
     {

src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/Routing/RoutingTestCases.razor

@@ -23,4 +23,13 @@
     <li>
         <a href="routing/complex-segment(value)">Complex segments</a>
     </li>
+    <li>
+        <a href="routing/not-found-ssr">Not found page for Static Server Rendering</a>
+    </li>
+    <li>
+        <a href="routing/not-found-webassembly">Not found page for Interactive WebAssembly rendering</a>
+    </li>
+    <li>
+        <a href="routing/not-found-server">Not found page for Interactive Server rendering</a>
+    </li>
 </ul>

src/Components/test/testassets/Components.WasmMinimal/Pages/NotFoundInteractiveServer.razor

@@ -0,0 +1,17 @@
+@page "/render-not-found-server"
+@using Microsoft.AspNetCore.Components;
+@using Microsoft.AspNetCore.Components.Web;
+@inject NavigationManager NavigationManager
+
+<p id="test-info">Any content</p>
+@if(RendererInfo.IsInteractive)
+{
+    <button id="trigger-not-found" @onclick="@TriggerNotFound">Trigger not found button</button>
+}
+
+@code{
+    private void TriggerNotFound()
+    {
+        NavigationManager.NotFound();
+    }
+}

src/Components/test/testassets/Components.WasmMinimal/Pages/NotFoundInteractiveWebassembly.razor

@@ -0,0 +1,17 @@
+@page "/render-not-found-webassembly"
+@using Microsoft.AspNetCore.Components;
+@using Microsoft.AspNetCore.Components.Web;
+@inject NavigationManager NavigationManager
+
+<p id="test-info">Any content</p>
+@if(RendererInfo.IsInteractive)
+{
+    <button id="trigger-not-found" @onclick="@TriggerNotFound">Trigger not found button</button>
+}
+
+@code{
+    private void TriggerNotFound()
+    {
+        NavigationManager.NotFound();
+    }
+}

src/Components/test/testassets/Components.WasmMinimal/Pages/NotFoundSSR.razor

@@ -0,0 +1,11 @@
+@page "/render-not-found-ssr"
+@inject NavigationManager NavigationManager
+
+<p id="test-info">Any content</p>
+
+@code{
+    protected override void OnInitialized()
+    {
+        NavigationManager.NotFound();
+    }
+}