Refactor ViewEngine to support partials.

This references WEBFX-95 and is the preliminary part to support Partial helpers.

src/Microsoft.AspNet.Mvc.Core/ActionResults/ViewResult.cs

@@ -42,7 +42,7 @@ namespace Microsoft.AspNet.Mvc
         private async Task<IView> FindView([NotNull] IDictionary<string, object> context,[NotNull] string viewName)
         {
             var result = await _viewEngine.FindView(context, viewName);
-            result.EnsureSuccess();
+
             return result.View;
         }
 

src/Microsoft.AspNet.Mvc.Core/ViewComponents/ViewViewComponentResult.cs

@@ -78,7 +78,7 @@ namespace Microsoft.AspNet.Mvc
         private async Task<IView> FindView([NotNull] IDictionary<string, object> context, [NotNull] string viewName)
         {
             var result = await _viewEngine.FindView(context, viewName);
-            result.EnsureSuccess();
+
             return result.View;
         }
     }

src/Microsoft.AspNet.Mvc.Razor/Properties/Resources.Designer.cs

@@ -58,6 +58,38 @@ namespace Microsoft.AspNet.Mvc.Razor
             return GetString("RenderBodyCannotBeCalled");
         }
 
+        /// <summary>
+        /// The partial view '{0}' was not found. The following locations were searched:{1}
+        /// </summary>
+        internal static string ViewEngine_PartialViewNotFound
+        {
+            get { return GetString("ViewEngine_PartialViewNotFound"); }
+        }
+
+        /// <summary>
+        /// The partial view '{0}' was not found. The following locations were searched:{1}
+        /// </summary>
+        internal static string FormatViewEngine_PartialViewNotFound(object p0, object p1)
+        {
+            return string.Format(CultureInfo.CurrentCulture, GetString("ViewEngine_PartialViewNotFound"), p0, p1);
+        }
+
+        /// <summary>
+        /// The view '{0}' was not found. The following locations were searched:{1}.
+        /// </summary>
+        internal static string ViewEngine_ViewNotFound
+        {
+            get { return GetString("ViewEngine_ViewNotFound"); }
+        }
+
+        /// <summary>
+        /// The view '{0}' was not found. The following locations were searched:{1}.
+        /// </summary>
+        internal static string FormatViewEngine_ViewNotFound(object p0, object p1)
+        {
+            return string.Format(CultureInfo.CurrentCulture, GetString("ViewEngine_ViewNotFound"), p0, p1);
+        }
+
         private static string GetString(string name, params string[] formatterNames)
         {
             var value = _resourceManager.GetString(name);

src/Microsoft.AspNet.Mvc.Razor/Resources.resx

@@ -126,4 +126,10 @@
   <data name="RenderBodyCannotBeCalled" xml:space="preserve">
     <value>RenderBody can only be called from a layout page.</value>
   </data>
+  <data name="ViewEngine_PartialViewNotFound" xml:space="preserve">
+    <value>The partial view '{0}' was not found. The following locations were searched:{1}</value>
+  </data>
+  <data name="ViewEngine_ViewNotFound" xml:space="preserve">
+    <value>The view '{0}' was not found. The following locations were searched:{1}.</value>
+  </data>
 </root>

src/Microsoft.AspNet.Mvc.Razor/ViewEngine/RazorViewEngine.cs

@@ -28,7 +28,34 @@ namespace Microsoft.AspNet.Mvc.Razor
             get { return _viewLocationFormats; }
         }
 
-        public async Task<ViewEngineResult> FindView([NotNull] IDictionary<string, object> context,[NotNull] string viewName)
+        public async Task<ViewEngineResult> FindView([NotNull] IDictionary<string, object> context,
+                                                     [NotNull] string viewName)
+        {
+            var viewEngineResult = await CreateViewEngineResult(context, viewName);
+            var errorMessage = Resources.FormatViewEngine_ViewNotFound(
+                                    viewName,
+                                    ToLocationString(viewEngineResult.SearchedLocations));
+
+            EnsureViewEngineResult(viewEngineResult, viewName, errorMessage);
+
+            return viewEngineResult;
+        }
+
+        public async Task<ViewEngineResult> FindPartialView([NotNull] IDictionary<string, object> context,
+                                                            [NotNull] string partialViewName)
+        {
+            var viewEngineResult = await CreateViewEngineResult(context, partialViewName);
+            var errorMessage = Resources.FormatViewEngine_PartialViewNotFound(
+                                    partialViewName, 
+                                    ToLocationString(viewEngineResult.SearchedLocations));
+
+            EnsureViewEngineResult(viewEngineResult, partialViewName, errorMessage);
+
+            return viewEngineResult;
+        }
+
+        private async Task<ViewEngineResult> CreateViewEngineResult([NotNull] IDictionary<string, object> context,
+                                                                    [NotNull] string viewName)
         {
             var nameRepresentsPath = IsSpecificPath(viewName);
 
@@ -59,6 +86,24 @@ namespace Microsoft.AspNet.Mvc.Razor
             }
         }
 
+        private void EnsureViewEngineResult(ViewEngineResult viewEngineResult, string viewName, string errorMessage)
+        {
+            if (!viewEngineResult.Success)
+            {
+                throw new InvalidOperationException(errorMessage);
+            }
+        }
+
+        private string ToLocationString(IEnumerable<string> locations)
+        {
+            if (locations != null)
+            {
+                return Environment.NewLine + string.Join(Environment.NewLine, locations);
+            }
+
+            return string.Empty;
+        }
+
         private static bool IsSpecificPath(string name)
         {
             char c = name[0];

src/Microsoft.AspNet.Mvc.Rendering/Properties/Resources.resx

@@ -141,7 +141,4 @@
   <data name="ViewData_WrongTModelType" xml:space="preserve">
     <value>The model item passed into the ViewDataDictionary is of type '{0}', but this ViewDataDictionary instance requires a model item of type '{1}'.</value>
   </data>
-  <data name="ViewEngine_ViewNotFound" xml:space="preserve">
-    <value>The view '{0}' was not found. The following locations were searched:{1}.</value>
-  </data>
 </root>

src/Microsoft.AspNet.Mvc.Rendering/View/IViewEngine.cs

@@ -6,5 +6,6 @@ namespace Microsoft.AspNet.Mvc.Rendering
     public interface IViewEngine
     {
         Task<ViewEngineResult> FindView([NotNull] IDictionary<string, object> context, [NotNull] string viewName);
+        Task<ViewEngineResult> FindPartialView([NotNull] IDictionary<string, object> context, [NotNull] string partialViewName);
     }
 }

src/Microsoft.AspNet.Mvc.Rendering/View/ViewEngineResult.cs

@@ -20,7 +20,8 @@ namespace Microsoft.AspNet.Mvc.Rendering
             get { return View != null; } 
         }
 
-        public static ViewEngineResult NotFound([NotNull] string viewName, [NotNull] IEnumerable<string> searchedLocations)
+        public static ViewEngineResult NotFound([NotNull] string viewName, 
+                                                [NotNull] IEnumerable<string> searchedLocations)
         {
             return new ViewEngineResult
             {
@@ -37,18 +38,5 @@ namespace Microsoft.AspNet.Mvc.Rendering
                 ViewName = viewName,
             };
         }
-
-        public ViewEngineResult EnsureSuccess()
-        {
-            if (Success)
-            {
-                return this;
-            }
-
-            var locationsText = Environment.NewLine + string.Join(Environment.NewLine, SearchedLocations);
-            throw new InvalidOperationException(Resources.FormatViewEngine_ViewNotFound(
-                ViewName,
-                 locationsText));
-        }
     }
 }