Initial support for JsonResult + Action result mutation from object to Json

samples/MvcSample/Home2Controller.cs

@@ -1,10 +1,13 @@
 using Microsoft.AspNet.Abstractions;
 using Microsoft.AspNet.Mvc;
+using System.Text;
 
 namespace MvcSample
 {
     public class Home2Controller
     {
+        private User _user = new User() { Name = "User Name", Address = "Home Address" };
+
         public Home2Controller(IActionResultHelper actionResultHelper)
         {
             Result = actionResultHelper;
@@ -36,5 +39,18 @@ namespace MvcSample
         {
             Context.Response.WriteAsync("Hello World raw");
         }
+
+        public IActionResult UserJson()
+        {
+            return new JsonResult(new User() { Name = "User Name", Address = "Home Address" })
+            {
+                Encoding = Encoding.UTF8
+            };
+        }
+
+        public User User()
+        {
+            return _user;
+        }
     }
 }

src/Microsoft.AspNet.Mvc/ActionResultFactory.cs

@@ -6,11 +6,46 @@ namespace Microsoft.AspNet.Mvc
     {
         public IActionResult CreateActionResult(Type declaredReturnType, object actionReturnValue, RequestContext requestContext)
         {
-            return new ContentResult
+            // optimize common path
+            IActionResult actionResult = actionReturnValue as IActionResult;
+
+            if (actionResult != null)
             {
-                ContentType = "text/plain",
-                Content = Convert.ToString(actionReturnValue),
-            };
+                return actionResult;
+            }
+
+            if (declaredReturnType == null)
+            {
+                throw new InvalidOperationException("Declared type must be passed");
+            }
+
+            if (typeof(IActionResult).IsAssignableFrom(declaredReturnType) && actionReturnValue == null)
+            {
+                throw new InvalidOperationException("Cannot return null from an action method declaring IActionResult or HttpResponseMessage");
+            }
+
+            if (declaredReturnType.IsGenericParameter)
+            {
+                // This can happen if somebody declares an action method as:
+                // public T Get<T>() { }
+                throw new InvalidOperationException("HttpActionDescriptor_NoConverterForGenericParamterTypeExists");
+            }
+
+            if (declaredReturnType.IsAssignableFrom(typeof(void)))
+            {
+                return new NoContentResult();
+            }
+
+            if (actionReturnValue is string)
+            {
+                return new ContentResult
+                {
+                    ContentType = "text/plain",
+                    Content = (string)actionReturnValue,
+                };
+            }
+
+            return new JsonResult(actionReturnValue);
         }
     }
 }

src/Microsoft.AspNet.Mvc/ActionResults/JsonResult.cs

@@ -0,0 +1,112 @@
+using System;
+using System.IO;
+using System.Text;
+using System.Threading.Tasks;
+using Microsoft.AspNet.Abstractions;
+using Newtonsoft.Json;
+
+namespace Microsoft.AspNet.Mvc
+{
+    public class JsonResult : IActionResult
+    {
+        private readonly object _returnValue;
+
+        private JsonSerializerSettings _jsonSerializerSettings;
+        private Encoding _encoding;
+
+        public JsonResult(object returnValue)
+        {
+            if (returnValue == null)
+            {
+                throw new ArgumentNullException("returnValue");
+            }
+
+            Encoding = Encoding.UTF8;
+
+            _returnValue = returnValue;
+        }
+
+        public JsonSerializerSettings SerializerSettings
+        {
+            get { return _jsonSerializerSettings; }
+
+            set
+            {
+                if (value == null)
+                {
+                    throw new ArgumentNullException("value");
+                }
+
+                _jsonSerializerSettings = value;
+            }
+        }
+
+        /// <summary>
+        /// Gets or sets a value indicating whether to indent elements when writing data. 
+        /// </summary>
+        public bool Indent { get; set; }
+
+        public Encoding Encoding
+        {
+            get { return _encoding; }
+            set
+            {
+                if (value == null)
+                {
+                    throw new ArgumentNullException("value");
+                }
+
+                _encoding = value;
+            }
+        }
+
+        public virtual JsonSerializerSettings CreateSerializerSettings()
+        {
+            return new JsonSerializerSettings()
+            {
+                MissingMemberHandling = MissingMemberHandling.Ignore,
+
+                // Do not change this setting
+                // Setting this to None prevents Json.NET from loading malicious, unsafe, or security-sensitive types.
+                TypeNameHandling = TypeNameHandling.None
+            };
+        }
+
+        public virtual JsonSerializer CreateJsonSerializer()
+        {
+            JsonSerializer jsonSerializer = JsonSerializer.Create(SerializerSettings);
+
+            return jsonSerializer;
+        }
+
+        public virtual JsonWriter CreateJsonWriter(Stream writeStream, Encoding effectiveEncoding)
+        {
+            JsonWriter jsonWriter = new JsonTextWriter(new StreamWriter(writeStream, effectiveEncoding));
+            if (Indent)
+            {
+                jsonWriter.Formatting = Newtonsoft.Json.Formatting.Indented;
+            }
+
+            return jsonWriter;
+        }
+
+        public async Task ExecuteResultAsync(RequestContext context)
+        {
+            HttpResponse response = context.HttpContext.Response;
+
+            Stream writeStream = response.Body;
+
+            response.ContentType = "application/json";
+
+            using (JsonWriter jsonWriter = CreateJsonWriter(writeStream, Encoding))
+            {
+                jsonWriter.CloseOutput = false;
+
+                JsonSerializer jsonSerializer = CreateJsonSerializer();
+                jsonSerializer.Serialize(jsonWriter, _returnValue);
+
+                jsonWriter.Flush();
+            }
+        }
+    }
+}

src/Microsoft.AspNet.Mvc/ControllerActionInvoker.cs

@@ -47,8 +47,7 @@ namespace Microsoft.AspNet.Mvc
 
             object actionReturnValue = method.Invoke(controller, null);
 
-            // If it's not already an IActionResult then call into the factory
-            var actionResult = actionReturnValue as IActionResult ?? _actionResultFactory.CreateActionResult(method.ReturnType, actionReturnValue, _requestContext);
+            var actionResult = _actionResultFactory.CreateActionResult(method.ReturnType, actionReturnValue, _requestContext);
 
             return actionResult.ExecuteResultAsync(_requestContext);
         }