From 6f305373cadf769a2ff9aab75932cf92ce8cc3fc Mon Sep 17 00:00:00 2001
From: Ryan Nowak <rynowak@microsoft.com>
Date: Tue, 16 Apr 2019 09:58:13 -0700
Subject: [PATCH] Allow fallback to controller to use MatcherPolicy

---
 .../DynamicControllerEndpointMatcherPolicy.cs   | 17 +++++++++++++----
 .../DynamicPageEndpointMatcherPolicy.cs         |  4 ++++
 .../Mvc.FunctionalTests/RoutingFallbackTest.cs  | 16 ++++++++++++++++
 .../Areas/Admin/FallbackController.cs           |  6 ++++++
 4 files changed, 39 insertions(+), 4 deletions(-)

diff --git a/src/Mvc/Mvc.Core/src/Routing/DynamicControllerEndpointMatcherPolicy.cs b/src/Mvc/Mvc.Core/src/Routing/DynamicControllerEndpointMatcherPolicy.cs
index 798a13f109..0dcc828c5f 100644
--- a/src/Mvc/Mvc.Core/src/Routing/DynamicControllerEndpointMatcherPolicy.cs
+++ b/src/Mvc/Mvc.Core/src/Routing/DynamicControllerEndpointMatcherPolicy.cs
@@ -14,15 +14,22 @@ namespace Microsoft.AspNetCore.Mvc.Routing
     internal class DynamicControllerEndpointMatcherPolicy : MatcherPolicy, IEndpointSelectorPolicy
     {
         private readonly DynamicControllerEndpointSelector _selector;
+        private readonly EndpointMetadataComparer _comparer;
 
-        public DynamicControllerEndpointMatcherPolicy(DynamicControllerEndpointSelector selector)
+        public DynamicControllerEndpointMatcherPolicy(DynamicControllerEndpointSelector selector, EndpointMetadataComparer comparer)
         {
             if (selector == null)
             {
                 throw new ArgumentNullException(nameof(selector));
             }
 
+            if (comparer == null)
+            {
+                throw new ArgumentNullException(nameof(comparer));
+            }
+
             _selector = selector;
+            _comparer = comparer;
         }
 
         public override int Order => int.MinValue + 100;
@@ -99,8 +106,6 @@ namespace Microsoft.AspNetCore.Mvc.Routing
                         "{ " + string.Join(", ", metadata.Values.Select(kvp => $"{kvp.Key}: {kvp.Value}")) + " }.");
                 }
 
-                var replacement = endpoints[0];
-                
                 // We need to provide the route values associated with this endpoint, so that features
                 // like URL generation work.
                 var values = new RouteValueDictionary(metadata.Values);
@@ -111,7 +116,11 @@ namespace Microsoft.AspNetCore.Mvc.Routing
                     values.TryAdd(kvp.Key, kvp.Value);
                 }
 
-                candidates.ReplaceEndpoint(i, replacement, values);
+                // Update the route values
+                candidates.ReplaceEndpoint(i, endpoint, values);
+
+                // Expand the list of endpoints
+                candidates.ExpandEndpoint(i, endpoints, _comparer);
             }
 
             return Task.CompletedTask;
diff --git a/src/Mvc/Mvc.RazorPages/src/Infrastructure/DynamicPageEndpointMatcherPolicy.cs b/src/Mvc/Mvc.RazorPages/src/Infrastructure/DynamicPageEndpointMatcherPolicy.cs
index cf41aac9fd..f7321e79b7 100644
--- a/src/Mvc/Mvc.RazorPages/src/Infrastructure/DynamicPageEndpointMatcherPolicy.cs
+++ b/src/Mvc/Mvc.RazorPages/src/Infrastructure/DynamicPageEndpointMatcherPolicy.cs
@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Linq;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Http;
@@ -106,6 +107,9 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure
                         "{ " + string.Join(", ", metadata.Values.Select(kvp => $"{kvp.Key}: {kvp.Value}")) + " }.");
                 }
 
+                // It should not be possible to have more than one result for pages.
+                Debug.Assert(endpoints.Count == 1);
+
                 var compiled = await _loader.LoadAsync(endpoints[0].Metadata.GetMetadata<PageActionDescriptor>());
                 var replacement = compiled.Endpoint;
                 
diff --git a/src/Mvc/test/Mvc.FunctionalTests/RoutingFallbackTest.cs b/src/Mvc/test/Mvc.FunctionalTests/RoutingFallbackTest.cs
index ed23c1fe02..eb41d3b7f4 100644
--- a/src/Mvc/test/Mvc.FunctionalTests/RoutingFallbackTest.cs
+++ b/src/Mvc/test/Mvc.FunctionalTests/RoutingFallbackTest.cs
@@ -69,6 +69,22 @@ namespace Microsoft.AspNetCore.Mvc.FunctionalTests
             Assert.Equal("Hello from fallback controller: /Admin/Fallback", content);
         }
 
+        [Fact]
+        public async Task Fallback_CanFallbackToControllerInAreaPost()
+        {
+            // Arrange
+            var url = "http://localhost/Admin/Foo";
+            var request = new HttpRequestMessage(HttpMethod.Post, url);
+
+            // Act
+            var response = await Client.SendAsync(request);
+            var content = await response.Content.ReadAsStringAsync();
+
+            // Assert
+            Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+            Assert.Equal("Hello from fallback controller POST: /Admin/Fallback", content);
+        }
+
         [Fact]
         public async Task Fallback_CanFallbackToPage()
         {
diff --git a/src/Mvc/test/WebSites/RoutingWebSite/Areas/Admin/FallbackController.cs b/src/Mvc/test/WebSites/RoutingWebSite/Areas/Admin/FallbackController.cs
index a15564d2b7..64d0cd7875 100644
--- a/src/Mvc/test/WebSites/RoutingWebSite/Areas/Admin/FallbackController.cs
+++ b/src/Mvc/test/WebSites/RoutingWebSite/Areas/Admin/FallbackController.cs
@@ -12,5 +12,11 @@ namespace RoutingWebSite.Areas.Admin
         {
             return Content("Hello from fallback controller: " + Url.Action());
         }
+
+        [HttpPost]
+        public ActionResult Index(int x)
+        {
+            return Content("Hello from fallback controller POST: " + Url.Action());
+        }
     }
 }