Supress interactive rendering on error scenarios

Author: javiercn

src/Components/Endpoints/src/Microsoft.AspNetCore.Components.Endpoints.csproj

@@ -48,6 +48,7 @@
     <Reference Include="Microsoft.AspNetCore.Antiforgery" />
     <Reference Include="Microsoft.AspNetCore.Components.Authorization" />
     <Reference Include="Microsoft.AspNetCore.Components.Web" />
+    <Reference Include="Microsoft.AspNetCore.Diagnostics.Abstractions" />
     <Reference Include="Microsoft.AspNetCore.DataProtection.Extensions" />
     <Reference Include="Microsoft.AspNetCore.Hosting.Abstractions" />
     <Reference Include="Microsoft.AspNetCore.Http" />

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

@@ -20,6 +20,7 @@ internal partial class EndpointHtmlRenderer
     private TextWriter? _streamingUpdatesWriter;
     private HashSet<int>? _visitedComponentIdsInCurrentStreamingBatch;
     private string? _ssrFramingCommentMarkup;
+    private bool _allowBoundaryMarkers;
 
     public void InitializeStreamingRenderingFraming(HttpContext httpContext)
     {
@@ -189,8 +190,8 @@ protected override void WriteComponentHtml(int componentId, TextWriter output)
     protected override void RenderChildComponent(TextWriter output, ref RenderTreeFrame componentFrame)
     {
         var componentId = componentFrame.ComponentId;
-        var sequenceAndKey = new SequenceAndKey(componentFrame.Sequence, componentFrame.ComponentKey);
-        WriteComponentHtml(componentId, output, allowBoundaryMarkers: true, sequenceAndKey);
+        var sequenceAndKey = new SequenceAndKey(componentFrame.Sequence, componentFrame.ComponentKey);       
+        WriteComponentHtml(componentId, output, _allowBoundaryMarkers, sequenceAndKey);
     }
 
     private void WriteComponentHtml(int componentId, TextWriter output, bool allowBoundaryMarkers, SequenceAndKey sequenceAndKey = default)

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

@@ -12,6 +12,7 @@
 using Microsoft.AspNetCore.Components.Rendering;
 using Microsoft.AspNetCore.Components.RenderTree;
 using Microsoft.AspNetCore.Components.Routing;
+using Microsoft.AspNetCore.Diagnostics;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Http.Extensions;
 using Microsoft.AspNetCore.Routing;
@@ -59,6 +60,7 @@ private void SetHttpContext(HttpContext httpContext)
         if (_httpContext is null)
         {
             _httpContext = httpContext;
+            _allowBoundaryMarkers = _httpContext.Features.Get<IExceptionHandlerFeature>() is null;
         }
         else if (_httpContext != httpContext)
         {

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

@@ -0,0 +1,35 @@
+@page "/Error"
+@using System.Diagnostics
+
+<PageTitle>Error</PageTitle>
+
+<h1 class="text-danger">Error.</h1>
+<h2 class="text-danger">An error occurred while processing your request.</h2>
+
+@if (ShowRequestId)
+{
+    <p>
+        <strong>Request ID:</strong> <code>@RequestId</code>
+    </p>
+}
+
+<h3>Development Mode</h3>
+<p>
+    Swapping to <strong>Development</strong> environment will display more detailed information about the error that occurred.
+</p>
+<p>
+    <strong>The Development environment shouldn't be enabled for deployed applications.</strong>
+    It can result in displaying sensitive information from exceptions to end users.
+    For local debugging, enable the <strong>Development</strong> environment by setting the <strong>ASPNETCORE_ENVIRONMENT</strong> environment variable to <strong>Development</strong>
+    and restarting the app.
+</p>
+
+@code{
+    [CascadingParameter] public HttpContext? HttpContext { get; set; }
+
+    public string? RequestId { get; set; }
+    public bool ShowRequestId => !string.IsNullOrEmpty(RequestId);
+
+    protected override void OnInitialized() =>
+        RequestId = Activity.Current?.Id ?? HttpContext?.TraceIdentifier;
+}

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

@@ -33,7 +33,7 @@
 
     [SupplyParameterFromForm] Customer? Value { get; set; }
 
-    protected override void OnInitialized() => Value ??= new();
+    protected override void OnInitialized() => throw new InvalidOperationException("Some error");
 
     bool _submitted = false;
     public void Submit() => _submitted = true;

src/Components/Samples/BlazorUnitedApp/Program.cs

@@ -3,8 +3,13 @@
 
 using BlazorUnitedApp;
 using BlazorUnitedApp.Data;
+using Microsoft.AspNetCore.Hosting.StaticWebAssets;
 
 var builder = WebApplication.CreateBuilder(args);
+// Enable this so that we can resolve static web assets in the Production environment
+// without publishing the app.
+// This is so that we can test the error page.
+StaticWebAssetsLoader.UseStaticWebAssets(builder.Environment, builder.Configuration);
 
 // Add services to the container.
 builder.Services.AddRazorComponents();
@@ -16,7 +21,7 @@
 // Configure the HTTP request pipeline.
 if (!app.Environment.IsDevelopment())
 {
-    app.UseExceptionHandler("/Error");
+    app.UseExceptionHandler("/Error", newScope: true);
     // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
     app.UseHsts();
 }