Add convenience methods for redirecting from a Razor Page back to itself

Fuxes #5953

src/Microsoft.AspNetCore.Mvc.RazorPages/Page.cs

@@ -138,6 +138,21 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages
             return new RedirectResult(url);
         }
 
+        /// <summary>
+        /// Redirects (<see cref="StatusCodes.Status302Found"/>) to the current page.
+        /// </summary>
+        /// <returns>The <see cref="RedirectToPageResult"/>.</returns>
+        protected RedirectToPageResult RedirectToPage()
+            => RedirectToPage(pageName: null);
+
+        /// <summary>
+        /// Redirects (<see cref="StatusCodes.Status302Found"/>) to the current page with the specified <paramref name="routeValues"/>.
+        /// </summary>
+        /// <param name="routeValues">The parameters for a route.</param>
+        /// <returns>The <see cref="RedirectToPageResult"/>.</returns>
+        protected RedirectToPageResult RedirectToPage(object routeValues)
+            => RedirectToPage(pageName: null, routeValues: routeValues);
+
         /// <summary>
         /// Redirects (<see cref="StatusCodes.Status302Found"/>) to the specified <paramref name="pageName"/>.
         /// </summary>

src/Microsoft.AspNetCore.Mvc.RazorPages/PageModel.cs

@@ -176,6 +176,21 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages
             return new RedirectResult(url);
         }
 
+        /// <summary>
+        /// Redirects (<see cref="StatusCodes.Status302Found"/>) to the current page.
+        /// </summary>
+        /// <returns>The <see cref="RedirectToPageResult"/>.</returns>
+        protected RedirectToPageResult RedirectToPage()
+            => RedirectToPage(pageName: null);
+
+        /// <summary>
+        /// Redirects (<see cref="StatusCodes.Status302Found"/>) to the current page with the specified <paramref name="routeValues"/>.
+        /// </summary>
+        /// <param name="routeValues">The parameters for a route.</param>
+        /// <returns>The <see cref="RedirectToPageResult"/>.</returns>
+        protected RedirectToPageResult RedirectToPage(object routeValues)
+            => RedirectToPage(pageName: null, routeValues: routeValues);
+
         /// <summary>
         /// Redirects (<see cref="StatusCodes.Status302Found"/>) to the specified <paramref name="pageName"/>.
         /// </summary>

src/Microsoft.AspNetCore.Mvc.RazorPages/PageUrlHelperExtensions.cs

@@ -9,7 +9,7 @@ namespace Microsoft.AspNetCore.Mvc
     /// <summary>
     /// Razor page specific extensions for <see cref="IUrlHelper"/>.
     /// </summary>
-    public static class PageNameUrlHelperExtensions
+    public static class PageUrlHelperExtensions
     {
         /// <summary>
         /// Generates a URL with an absolute path for the specified <paramref name="pageName"/>.

src/Microsoft.AspNetCore.Mvc.RazorPages/RedirectToPageResult.cs

@@ -130,12 +130,6 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages
                 throw new ArgumentNullException(nameof(context));
             }
 
-            if (string.IsNullOrEmpty(PageName))
-            {
-                throw new InvalidOperationException(
-                    Resources.FormatPropertyOfTypeCannotBeNull(nameof(PageName), nameof(RedirectToPageResult)));
-            }
-
             var executor = context.HttpContext.RequestServices.GetRequiredService<RedirectToPageResultExecutor>();
             executor.Execute(context, this);
         }

test/Microsoft.AspNetCore.Mvc.FunctionalTests/RazorPagesTest.cs

@@ -677,6 +677,29 @@ Microsoft.AspNetCore.Mvc.ViewFeatures.ViewDataDictionary`1[AspNetCore._InjectedP
             Assert.Equal(expected, response.Headers.Location.ToString());
         }
 
+        
+        [Fact]
+        public async Task RedirectToSelfWorks()
+        {
+            // Arrange
+            var expected = "/Pages/Redirects/RedirectToSelf?user=37";
+            var request = new HttpRequestMessage(HttpMethod.Post, "/Pages/Redirects/RedirectToSelf")
+            {
+                Content = new FormUrlEncodedContent(new KeyValuePair<string, string>[]
+                {
+                    new KeyValuePair<string, string>("value", "37"),
+                }),
+            };
+
+            // Act
+            await AddAntiforgeryHeaders(request);
+            var response = await Client.SendAsync(request);
+
+            // Assert
+            Assert.Equal(HttpStatusCode.Redirect, response.StatusCode);
+            Assert.Equal(expected, response.Headers.Location.ToString());
+        }
+
         private async Task AddAntiforgeryHeaders(HttpRequestMessage request)
         {
             var getResponse = await Client.GetAsync(request.RequestUri);

test/Microsoft.AspNetCore.Mvc.RazorPages.Test/RedirectToPageResultTest.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections.Generic;
 using System.Threading.Tasks;
+using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc.Abstractions;
 using Microsoft.AspNetCore.Mvc.RazorPages.Internal;
@@ -123,6 +124,56 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages
             Assert.Equal("test-fragment", context.Fragment);
         }
 
+        [Fact]
+        public async Task RedirectToPage_WithNullPage_UsesAmbientValue()
+        {
+            // Arrange
+            var expected = "path/to/this-page";
+            var httpContext = new Mock<HttpContext>();
+            var httpResponse = new Mock<HttpResponse>();
+            httpContext.SetupGet(c => c.Response)
+                .Returns(httpResponse.Object);
+            httpContext.SetupGet(c => c.RequestServices)
+                .Returns(CreateServices());
+            var routeData = new RouteData
+            {
+                Values =
+                {
+                    ["page"] = expected,
+                }
+            };
+
+            var actionContext = new ActionContext(
+                httpContext.Object,
+                routeData,
+                new ActionDescriptor());
+
+            UrlRouteContext context = null;
+            var urlHelper = new Mock<IUrlHelper>();
+            urlHelper.Setup(h => h.RouteUrl(It.IsAny<UrlRouteContext>()))
+                .Callback((UrlRouteContext c) => context = c)
+                .Returns("some-value");
+            urlHelper.SetupGet(h => h.ActionContext)
+                .Returns(actionContext);
+            var pageName = (string)null;
+            var result = new RedirectToPageResult(pageName)
+            {
+                UrlHelper = urlHelper.Object,
+            };
+
+            // Act
+            await result.ExecuteResultAsync(actionContext);
+
+            // Assert
+            Assert.NotNull(context);
+            Assert.Collection(Assert.IsType<RouteValueDictionary>(context.Values),
+               value =>
+               {
+                   Assert.Equal("page", value.Key);
+                   Assert.Equal(expected, value.Value);
+               });
+        }
+
         private static IServiceProvider CreateServices(IUrlHelperFactory factory = null)
         {
             var services = new ServiceCollection();

test/WebSites/RazorPagesWebSite/Pages/Redirects/RedirectToSelf.cshtml

@@ -0,0 +1,9 @@
+@page
+@functions
+{
+    public IActionResult OnPost(int value) => RedirectToPage(new { user = value });
+}
+
+<form action="">
+    @Html.AntiForgeryToken()
+</form>