CR Feedback, add ordering sample to the MVCSample.

null result handling in ActionResultFilterEndPoint

samples/MvcSample/Filters/UserNameProvider.cs

@@ -0,0 +1,28 @@
+using System;
+using System.Threading.Tasks;
+using Microsoft.AspNet.Mvc;
+
+namespace MvcSample.Filters
+{
+    public class UserNameProvider : ActionFilterAttribute
+    {
+        private static readonly string[] _userNames = new[] { "Jon", "David", "Goliath" };
+        private static int _index;
+
+        public override async Task Invoke(ActionFilterContext context, Func<Task> next)
+        {
+            object originalUserName = null;
+
+            context.ActionParameters.TryGetValue("userName", out originalUserName);
+
+            var userName = originalUserName as string;
+
+            if (string.IsNullOrWhiteSpace(userName))
+            {
+                context.ActionParameters["userName"] = _userNames[(_index++)%3];
+            }
+
+            await next();
+        }
+    }
+}

samples/MvcSample/FiltersController.cs

@@ -8,6 +8,8 @@ namespace MvcSample
     [ServiceFilter(typeof(PassThroughAttribute))]
     [PassThrough(Order = 0)]
     [PassThrough(Order = 2)]
+    [InspectResultPage]
+    [UserNameProvider(Order = -1)]
     public class FiltersController : Controller
     {
         private readonly User _user = new User() { Name = "User Name", Address = "Home Address" };
@@ -15,9 +17,13 @@ namespace MvcSample
         // TODO: Add a real filter here
         [ServiceFilter(typeof(PassThroughAttribute))]
         [AgeEnhancer]
-        [InspectResultPage]
-        public IActionResult Index(int age)
+        public IActionResult Index(int age, string userName)
         {
+            if (!string.IsNullOrEmpty(userName))
+            {
+                _user.Name = userName;
+            }
+
             _user.Age = age;
 
             return View("MyView", _user);

src/Microsoft.AspNet.Mvc.Core/Filters/ActionResultFilterEndPoint.cs

@@ -8,6 +8,12 @@ namespace Microsoft.AspNet.Mvc.Filters
     {
         public async Task Invoke(ActionResultFilterContext context, Func<Task> next)
         {
+            // result can get cleared at any point in the pipeline
+            if (context.Result == null)
+            {
+                context.Result = new EmptyResult();
+            }
+
             await context.Result.ExecuteResultAsync(context.ActionContext);
         }
     }

src/Microsoft.AspNet.Mvc.Core/Filters/AuthorizationFilterEndPoint.cs

@@ -3,7 +3,7 @@ using System.Threading.Tasks;
 
 namespace Microsoft.AspNet.Mvc.Filters
 {
-    // This one lives in the FilterDescriptors namespace, and only intended to be consumed by folks that rewrite the action invoker.
+    // This one lives in the Filters namespace, and only intended to be consumed by folks that rewrite the action invoker.
     public class AuthorizationFilterEndPoint : IAuthorizationFilter
     {
         public bool EndPointCalled { get; private set; }

src/Microsoft.AspNet.Mvc.Core/Filters/FilterDescriptor.cs

@@ -4,13 +4,13 @@ namespace Microsoft.AspNet.Mvc
 {
     public class FilterDescriptor
     {
-        public FilterDescriptor([NotNull]IFilter filter, int origin)
+        public FilterDescriptor([NotNull]IFilter filter, int filterScope)
         {
             Filter = filter;
-            Origin = origin;
+            Scope = filterScope;
         }
 
         public IFilter Filter { get; private set; }
-        public int Origin { get; private set; }
+        public int Scope { get; private set; }
     }
 }

src/Microsoft.AspNet.Mvc.Core/Filters/FilterDescriptorOrderComparer.cs

@@ -12,7 +12,7 @@ namespace Microsoft.AspNet.Mvc
         {
             if (x.Filter.Order == y.Filter.Order)
             {
-                return x.Origin.CompareTo(y.Origin);
+                return x.Scope.CompareTo(y.Scope);
             }
             else
             {

src/Microsoft.AspNet.Mvc.Core/Filters/FilterScope.cs

@@ -1,6 +1,6 @@
 namespace Microsoft.AspNet.Mvc
 {
-    public static class FilterOrigin
+    public static class FilterScope
     {
         public static readonly int Action = 100;
         public static readonly int Controller = 200;

src/Microsoft.AspNet.Mvc.Core/ReflectedActionDescriptorProvider.cs

@@ -25,7 +25,7 @@ namespace Microsoft.AspNet.Mvc
             _parameterDescriptorFactory = parameterDescriptorFactory;
             var filters = globalFilters ?? Enumerable.Empty<IFilter>();
 
-            _globalFilters = filters.Select(f => new FilterDescriptor(f, FilterOrigin.Global));
+            _globalFilters = filters.Select(f => new FilterDescriptor(f, FilterScope.Global));
         }
 
         public int Order
@@ -51,7 +51,7 @@ namespace Microsoft.AspNet.Mvc
                 var controllerAttributes = cd.ControllerTypeInfo.GetCustomAttributes(inherit: true).ToArray();
                 var globalAndControllerFilters =
                     controllerAttributes.OfType<IFilter>()
-                                        .Select(filter => new FilterDescriptor(filter, FilterOrigin.Controller))
+                                        .Select(filter => new FilterDescriptor(filter, FilterScope.Controller))
                                         .Concat(_globalFilters)
                                         .OrderBy(d => d, FilterDescriptorOrderComparer.Comparer)
                                         .ToArray();
@@ -112,7 +112,7 @@ namespace Microsoft.AspNet.Mvc
 
             var attributes = methodInfo.GetCustomAttributes(inherit: true).ToArray();
 
-            var filtersFromAction = attributes.OfType<IFilter>().Select(filter => new FilterDescriptor(filter, FilterOrigin.Action));
+            var filtersFromAction = attributes.OfType<IFilter>().Select(filter => new FilterDescriptor(filter, FilterScope.Action));
 
             ad.FilterDescriptors = filtersFromAction.Concat(globalAndControllerFilters)
                                                     .OrderBy(d => d, FilterDescriptorOrderComparer.Comparer)