Supply HttpContext as cascading value

Author: SteveSandersonMS

src/Components/Endpoints/src/DependencyInjection/RazorComponentsServiceCollectionExtensions.cs

@@ -63,6 +63,7 @@ public static IRazorComponentsBuilder AddRazorComponents(this IServiceCollection
         services.TryAddScoped<EndpointRoutingStateProvider>();
         services.TryAddScoped<IRoutingStateProvider>(sp => sp.GetRequiredService<EndpointRoutingStateProvider>());
         services.AddSupplyValueFromQueryProvider();
+        services.AddCascadingValue(sp => sp.GetRequiredService<EndpointHtmlRenderer>().HttpContext);
 
         // Form handling
         services.AddSupplyValueFromFormProvider();

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

@@ -52,6 +52,8 @@ public EndpointHtmlRenderer(IServiceProvider serviceProvider, ILoggerFactory log
         _services = serviceProvider;
     }
 
+    internal HttpContext? HttpContext => _httpContext;
+
     private void SetHttpContext(HttpContext httpContext)
     {
         if (_httpContext is null)

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

@@ -1,6 +1,8 @@
 // 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.Infrastructure;
 using Microsoft.AspNetCore.Components.E2ETest.Infrastructure.ServerFixtures;
@@ -35,4 +37,16 @@ public void CanRenderLargeComponentsWithServerRenderMode()
         Assert.Equal(result, Browser.FindElement(By.Id("server-prerender")).Text);
         Assert.Equal(result, Browser.FindElement(By.Id("server-prerender")).Text);
     }
+
+    [Fact]
+    public async Task CanUseHttpContextRequestAndResponse()
+    {
+        Navigate($"{ServerPathBase}/httpcontext");
+        Browser.Equal("GET", () => Browser.FindElement(By.Id("request-method")).Text);
+        Browser.Equal("/httpcontext", () => Browser.FindElement(By.Id("request-path")).Text);
+
+        // We can't see the response status code using Selenium, so make a direct request
+        var response = await new HttpClient().GetAsync(Browser.Url);
+        Assert.Equal(HttpStatusCode.Created, response.StatusCode);
+    }
 }

src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/AccessHttpContext.razor

@@ -0,0 +1,20 @@
+@page "/httpcontext"
+
+<h1>HttpContext</h1>
+
+<p>
+    Request method: <span id="request-method">@Ctx.Request.Method</span>
+</p>
+<p>
+    Request path: <span id="request-path">@Ctx.Request.Path</span>
+</p>
+
+@code {
+    [CascadingParameter] public HttpContext Ctx { get; set; }
+
+    protected override void OnInitialized()
+    {
+        // Show we can change the response status code
+        Ctx.Response.StatusCode = 201;
+    }
+}