Adding errors in ModelState

Mvc.sln

@@ -1,7 +1,7 @@
 
 Microsoft Visual Studio Solution File, Format Version 12.00
 # Visual Studio 14
-VisualStudioVersion = 14.0.22726.0
+VisualStudioVersion = 14.0.22806.0
 MinimumVisualStudioVersion = 10.0.40219.1
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "samples", "samples", "{DAAE4C74-D06F-4874-A166-33305D2643CE}"
 EndProject
@@ -160,6 +160,8 @@ Project("{8BB2217D-0F2D-49D1-97BC-3654ED321F3B}") = "Microsoft.AspNet.JsonPatch.
 EndProject
 Project("{8BB2217D-0F2D-49D1-97BC-3654ED321F3B}") = "Microsoft.AspNet.JsonPatch", "src\Microsoft.AspNet.JsonPatch\Microsoft.AspNet.JsonPatch.xproj", "{4D55F4D8-633B-462F-A5B1-FEB84BD2D534}"
 EndProject
+Project("{8BB2217D-0F2D-49D1-97BC-3654ED321F3B}") = "JsonPatchWebSite", "test\WebSites\JsonPatchWebSite\JsonPatchWebSite.xproj", "{DAB1252D-577C-4912-98BE-1A812BF83F86}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -950,6 +952,18 @@ Global
 		{4D55F4D8-633B-462F-A5B1-FEB84BD2D534}.Release|Mixed Platforms.Build.0 = Release|Any CPU
 		{4D55F4D8-633B-462F-A5B1-FEB84BD2D534}.Release|x86.ActiveCfg = Release|Any CPU
 		{4D55F4D8-633B-462F-A5B1-FEB84BD2D534}.Release|x86.Build.0 = Release|Any CPU
+		{DAB1252D-577C-4912-98BE-1A812BF83F86}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{DAB1252D-577C-4912-98BE-1A812BF83F86}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{DAB1252D-577C-4912-98BE-1A812BF83F86}.Debug|Mixed Platforms.ActiveCfg = Debug|Any CPU
+		{DAB1252D-577C-4912-98BE-1A812BF83F86}.Debug|Mixed Platforms.Build.0 = Debug|Any CPU
+		{DAB1252D-577C-4912-98BE-1A812BF83F86}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{DAB1252D-577C-4912-98BE-1A812BF83F86}.Debug|x86.Build.0 = Debug|Any CPU
+		{DAB1252D-577C-4912-98BE-1A812BF83F86}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{DAB1252D-577C-4912-98BE-1A812BF83F86}.Release|Any CPU.Build.0 = Release|Any CPU
+		{DAB1252D-577C-4912-98BE-1A812BF83F86}.Release|Mixed Platforms.ActiveCfg = Release|Any CPU
+		{DAB1252D-577C-4912-98BE-1A812BF83F86}.Release|Mixed Platforms.Build.0 = Release|Any CPU
+		{DAB1252D-577C-4912-98BE-1A812BF83F86}.Release|x86.ActiveCfg = Release|Any CPU
+		{DAB1252D-577C-4912-98BE-1A812BF83F86}.Release|x86.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -1028,5 +1042,6 @@ Global
 		{B42D4844-FFF8-4EC2-88D1-3AE95234D9EB} = {16703B76-C9F7-4C75-AE6C-53D92E308E3C}
 		{81C20848-E063-4E12-AC40-0B55A532C16C} = {3BA657BF-28B1-42DA-B5B0-1C4601FCF7B1}
 		{4D55F4D8-633B-462F-A5B1-FEB84BD2D534} = {32285FA4-6B46-4D6B-A840-2B13E4C8B58E}
+		{DAB1252D-577C-4912-98BE-1A812BF83F86} = {16703B76-C9F7-4C75-AE6C-53D92E308E3C}
 	EndGlobalSection
 EndGlobal

samples/MvcSample.Web/Controllers/JsonPatchController.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System.Collections.Generic;
+using System.Linq;
 using Microsoft.AspNet.JsonPatch;
 using Microsoft.AspNet.Mvc;
 
@@ -34,7 +35,12 @@ namespace MvcSample.Web.Controllers
                 }
             };
 
-            patchDoc.ApplyTo(customer);
+            patchDoc.ApplyTo(customer, ModelState);
+
+            if (!ModelState.IsValid)
+            {
+                return HttpBadRequest(ModelState);
+            }
 
             return new ObjectResult(customer);
         }

samples/MvcSample.Web/Views/JsonPatch/Index.cshtml

@@ -7,9 +7,9 @@
                 "Orders": [{"OrderName": "Order1"},
                          {"OrderName": "Order2"}]
                 };
-            $('#currentlabel').text(JSON.stringify(currentObj))
+            $('#currentLabel').text(JSON.stringify(currentObj))
 
-            $('#addorder').on("click", function () {
+            $('#addOrder').on("click", function () {
                 var obj = [{
                     "op": "Add",
                     "path": "Customer/Orders/2",
@@ -22,12 +22,34 @@
                     dataType: 'json',
                     contentType: 'application/json-patch+json',
                     success: function (data) {
-                        $('#addlabel').text(JSON.stringify(data))
+                        $('#addLabel').text(JSON.stringify(data))
                     }
                 });
             });
 
-            $('#removeorder').on("click", function () {
+            $('#invalidAddOrder').on("click", function () {
+                var obj = [{
+                    "op": "Add",
+                    "path": "Customer/Orders/5",
+                    "value": { "OrderName": "Name5" }
+                }]
+                $.ajax({
+                    url: 'jsonpatch',
+                    type: 'PATCH',
+                    data: JSON.stringify(obj),
+                    dataType: 'json',
+                    contentType: 'application/json-patch+json',
+                    success: function (data) {
+                        $('#invalidAddLabel').text(data)
+                    },
+                    error: function (request, status, error) {
+                        $('#invalidAddLabel').text(error)
+                    }
+                });
+            });
+
+
+            $('#removeOrder').on("click", function () {
                 var obj = [{
                     "op": "Remove",
                     "path": "Customer/Name"
@@ -39,12 +61,12 @@
                     dataType: 'json',
                     contentType: 'application/json-patch+json',
                     success: function (data) {
-                        $('#removelabel').text(JSON.stringify(data))
+                        $('#removeLabel').text(JSON.stringify(data))
                     }
                 });
             });
 
-            $('#moveorder').on("click", function () {
+            $('#moveOrder').on("click", function () {
                 var obj = [{
                     "op": "Move",
                     "from": "Customer/Orders/0",
@@ -57,12 +79,12 @@
                     dataType: 'json',
                     contentType: 'application/json-patch+json',
                     success: function (data) {
-                        $('#movelabel').text(JSON.stringify(data))
+                        $('#moveLabel').text(JSON.stringify(data))
                     }
                 });
             });
 
-            $('#replaceorder').on("click", function () {
+            $('#replaceOrder').on("click", function () {
                 var obj = [{
                     "op": "Replace",
                     "path": "Customer/Name",
@@ -75,7 +97,7 @@
                     dataType: 'json',
                     contentType: 'application/json-patch+json',
                     success: function (data) {
-                        $('#replacelabel').text(JSON.stringify(data))
+                        $('#replaceLabel').text(JSON.stringify(data))
                     }
                 });
             });
@@ -86,29 +108,35 @@
     <div>
         <label>Current Customer</label>
         <br />
-        <label id="currentlabel" name="currentlabel"></label>
+        <label id="currentLabel" name="currentLabel"></label>
         <br />
     </div>
     <div>
-        <button id="addorder" type="submit" class="btn btn-primary"> Add </button>
+        <button id="addOrder" type="submit" class="btn btn-primary"> Add </button>
         <br />
-        <label id="addlabel" name="addlabel"></label>
+        <label id="addLabel" name="addLabel"></label>
         <br />
     </div>
     <div>
-        <button id="removeorder" type="submit" class="btn btn-primary"> Remove </button>
+        <button id="invalidAddOrder" type="submit" class="btn btn-primary"> Invalid Add </button>
         <br />
-        <label id="removelabel" name="removelabel"></label>
+        <label id="invalidAddLabel" name="invalidAddLabel"></label>
-    </div>
-    <div>
-        <button id="moveorder" type="submit" class="btn btn-primary"> Move </button>
-        <br />
-        <label id="movelabel" name="movelabel"></label>
         <br />
     </div>
     <div>
-        <button id="replaceorder" type="submit" class="btn btn-primary"> Replace </button>
+        <button id="removeOrder" type="submit" class="btn btn-primary"> Remove </button>
         <br />
-        <label id="replacelabel" name="replacelabel"></label>
+        <label id="removeLabel" name="removeLabel"></label>
+    </div>
+    <div>
+        <button id="moveOrder" type="submit" class="btn btn-primary"> Move </button>
+        <br />
+        <label id="moveLabel" name="moveLabel"></label>
+        <br />
+    </div>
+    <div>
+        <button id="replaceOrder" type="submit" class="btn btn-primary"> Replace </button>
+        <br />
+        <label id="replaceLabel" name="replaceLabel"></label>
     </div>
 </body>

src/Microsoft.AspNet.JsonPatch/Adapters/IObjectAdapter.cs

@@ -1,16 +1,21 @@
 // Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using Microsoft.AspNet.JsonPatch.Operations;
+
 namespace Microsoft.AspNet.JsonPatch.Adapters
 {
-    public interface IObjectAdapter<T>
+    /// <summary>
-      where T : class
+    /// Defines the operations that can be performed on a JSON patch document.
+    /// </summary>
+    /// <typeparam name="T"></typeparam>
+    public interface IObjectAdapter<T> where T : class
     {
-        void Add(Microsoft.AspNet.JsonPatch.Operations.Operation<T> operation, T objectToApplyTo);
+        void Add(Operation<T> operation, T objectToApplyTo);
-        void Copy(Microsoft.AspNet.JsonPatch.Operations.Operation<T> operation, T objectToApplyTo);
+        void Copy(Operation<T> operation, T objectToApplyTo);
-        void Move(Microsoft.AspNet.JsonPatch.Operations.Operation<T> operation, T objectToApplyTo);
+        void Move(Operation<T> operation, T objectToApplyTo);
-        void Remove(Microsoft.AspNet.JsonPatch.Operations.Operation<T> operation, T objectToApplyTo);
+        void Remove(Operation<T> operation, T objectToApplyTo);
-        void Replace(Microsoft.AspNet.JsonPatch.Operations.Operation<T> operation, T objectToApplyTo);
+        void Replace(Operation<T> operation, T objectToApplyTo);
-        void Test(Microsoft.AspNet.JsonPatch.Operations.Operation<T> operation, T objectToApplyTo);
+        void Test(Operation<T> operation, T objectToApplyTo);
     }
 }

src/Microsoft.AspNet.JsonPatch/Adapters/ObjectAdapter.cs

@@ -7,20 +7,34 @@ using System.Reflection;
 using Microsoft.AspNet.JsonPatch.Exceptions;
 using Microsoft.AspNet.JsonPatch.Helpers;
 using Microsoft.AspNet.JsonPatch.Operations;
-using Newtonsoft.Json;
 using Newtonsoft.Json.Serialization;
 
 namespace Microsoft.AspNet.JsonPatch.Adapters
 {
+    /// <inheritdoc />
     public class ObjectAdapter<T> : IObjectAdapter<T> where T : class
     {
-        public IContractResolver ContractResolver { get; set; }
+        /// <summary>
-
+        /// Initializes a new instance of <see cref="ObjectAdapter{T}"/>.
-        public ObjectAdapter(IContractResolver contractResolver)
+        /// </summary>
+        /// <param name="contractResolver">The <see cref="IContractResolver"/>.</param>
+        /// <param name="logErrorAction">The <see cref="Action"/> for logging <see cref="JsonPatchError{T}"/>.</param>
+        public ObjectAdapter(IContractResolver contractResolver, Action<JsonPatchError<T>> logErrorAction)
         {
             ContractResolver = contractResolver;
+            LogErrorAction = logErrorAction;
         }
 
+        /// <summary>
+        /// Gets or sets the <see cref="IContractResolver"/>.
+        /// </summary>
+        public IContractResolver ContractResolver { get; }
+
+        /// <summary>
+        /// Action for logging <see cref="JsonPatchError{T}"/>.
+        /// </summary>
+        public Action<JsonPatchError<T>> LogErrorAction { get; }
+
         /// <summary>
         /// The "add" operation performs one of the following functions,
         /// depending upon what the target location references:
@@ -123,7 +137,10 @@ namespace Microsoft.AspNet.JsonPatch.Adapters
                 .FindPropertyAndParent(objectToApplyTo, actualPathToProperty, ContractResolver);
 
             // does property at path exist?
-            CheckIfPropertyExists(patchProperty, objectToApplyTo, operationToReport, path);
+            if (!CheckIfPropertyExists(patchProperty, objectToApplyTo, operationToReport, path))
+            {
+                return;
+            }
 
             // it exists.  If it' an array, add to that array.  If it's not, we replace.
             // is the path an array (but not a string (= char[]))?  In this case,
@@ -139,7 +156,10 @@ namespace Microsoft.AspNet.JsonPatch.Adapters
 
                     var conversionResult = PropertyHelpers.ConvertToActualType(genericTypeOfArray, value);
 
-                    CheckIfPropertyCanBeSet(conversionResult, objectToApplyTo, operationToReport, path);
+                    if (!CheckIfPropertyCanBeSet(conversionResult, objectToApplyTo, operationToReport, path))
+                    {
+                        return;
+                    }
 
                     // get value (it can be cast, we just checked that)
                     var array = (IList)patchProperty.Property.ValueProvider.GetValue(patchProperty.Parent);
@@ -157,19 +177,23 @@ namespace Microsoft.AspNet.JsonPatch.Adapters
                         }
                         else
                         {
-                            throw new JsonPatchException<T>(
+                            LogError(new JsonPatchError<T>(
+                                objectToApplyTo,
                                 operationToReport,
-                                Resources.FormatInvalidIndexForArrayProperty(operationToReport.op, path),
+                                Resources.FormatInvalidIndexForArrayProperty(operationToReport.op, path)));
-                                objectToApplyTo);
+
+                            return;
                         }
                     }
                 }
                 else
                 {
-                    throw new JsonPatchException<T>(
+                    LogError(new JsonPatchError<T>(
+                        objectToApplyTo,
                         operationToReport,
-                        Resources.FormatInvalidPathForArrayProperty(operationToReport.op, path),
+                        Resources.FormatInvalidIndexForArrayProperty(operationToReport.op, path)));
-                        objectToApplyTo);
+
+                    return;
                 }
             }
             else
@@ -179,7 +203,10 @@ namespace Microsoft.AspNet.JsonPatch.Adapters
                     value);
 
                 // Is conversion successful
-                CheckIfPropertyCanBeSet(conversionResultTuple, objectToApplyTo, operationToReport, path);
+                if (!CheckIfPropertyCanBeSet(conversionResultTuple, objectToApplyTo, operationToReport, path))
+                {
+                    return;
+                }
 
                 patchProperty.Property.ValueProvider.SetValue(
                         patchProperty.Parent,
@@ -229,7 +256,10 @@ namespace Microsoft.AspNet.JsonPatch.Adapters
                 .FindPropertyAndParent(objectToApplyTo, actualFromProperty, ContractResolver);
 
             // does property at from exist?
-            CheckIfPropertyExists(patchProperty, objectToApplyTo, operation, operation.from);
+            if (!CheckIfPropertyExists(patchProperty, objectToApplyTo, operation, operation.from))
+            {
+                return;
+            }
 
             // is the path an array (but not a string (= char[]))?  In this case,
             // the path must end with "/position" or "/-", which we already determined before.
@@ -245,20 +275,24 @@ namespace Microsoft.AspNet.JsonPatch.Adapters
 
                     if (array.Count <= positionAsInteger)
                     {
-                        throw new JsonPatchException<T>(
+                        LogError(new JsonPatchError<T>(
+                            objectToApplyTo,
                             operation,
-                            Resources.FormatInvalidIndexForArrayProperty(operation.op, operation.from),
+                            Resources.FormatInvalidIndexForArrayProperty(operation.op, operation.from)));
-                            objectToApplyTo);
+
+                        return;
                     }
 
                     valueAtFromLocation = array[positionAsInteger];
                 }
                 else
                 {
-                    throw new JsonPatchException<T>(
+                    LogError(new JsonPatchError<T>(
+                        objectToApplyTo,
                         operation,
-                        Resources.FormatInvalidPathForArrayProperty(operation.op, operation.from),
+                        Resources.FormatInvalidPathForArrayProperty(operation.op, operation.from)));
-                        objectToApplyTo);
+
+                    return;
                 }
             }
             else
@@ -324,7 +358,10 @@ namespace Microsoft.AspNet.JsonPatch.Adapters
                 .FindPropertyAndParent(objectToApplyTo, actualPathToProperty, ContractResolver);
 
             // does the target location exist?
-            CheckIfPropertyExists(patchProperty, objectToApplyTo, operationToReport, path);
+            if (!CheckIfPropertyExists(patchProperty, objectToApplyTo, operationToReport, path))
+            {
+                return;
+            }
 
             // get the property, and remove it - in this case, for DTO's, that means setting
             // it to null or its default value; in case of an array, remove at provided index
@@ -352,19 +389,23 @@ namespace Microsoft.AspNet.JsonPatch.Adapters
                         }
                         else
                         {
-                            throw new JsonPatchException<T>(
+                            LogError(new JsonPatchError<T>(
+                                objectToApplyTo,
                                 operationToReport,
-                                Resources.FormatInvalidIndexForArrayProperty(operationToReport.op, path),
+                                Resources.FormatInvalidIndexForArrayProperty(operationToReport.op, path)));
-                                objectToApplyTo);
+
+                            return;
                         }
                     }
                 }
                 else
                 {
-                    throw new JsonPatchException<T>(
+                    LogError(new JsonPatchError<T>(
+                        objectToApplyTo,
                         operationToReport,
-                        Resources.FormatInvalidPathForArrayProperty(operationToReport.op, path),
+                        Resources.FormatInvalidPathForArrayProperty(operationToReport.op, path)));
-                        objectToApplyTo);
+
+                    return;
                 }
             }
             else
@@ -451,10 +492,13 @@ namespace Microsoft.AspNet.JsonPatch.Adapters
                 .FindPropertyAndParent(objectToApplyTo, actualPathProperty, ContractResolver);
 
             // does property at path exist?
-            CheckIfPropertyExists(patchProperty, objectToApplyTo, operation, operation.path);
+            if (!CheckIfPropertyExists(patchProperty, objectToApplyTo, operation, operation.path))
+            {
+                return;
+            }
 
             // get the property path
-            Type typeOfFinalPropertyAtPathLocation;
+            Type typeOfFinalPropertyAtPathLocation = null;
 
             // is the path an array (but not a string (= char[]))?  In this case,
             // the path must end with "/position" or "/-", which we already determined before.
@@ -471,20 +515,24 @@ namespace Microsoft.AspNet.JsonPatch.Adapters
 
                     if (array.Count <= positionInPathAsInteger)
                     {
-                        throw new JsonPatchException<T>(
+                        LogError(new JsonPatchError<T>(
+                            objectToApplyTo,
                             operation,
-                            Resources.FormatInvalidIndexForArrayProperty(operation.op, operation.path),
+                            Resources.FormatInvalidIndexForArrayProperty(operation.op, operation.path)));
-                            objectToApplyTo);
+
+                        return;
                     }
 
                     valueAtPathLocation = array[positionInPathAsInteger];
                 }
                 else
                 {
-                    throw new JsonPatchException<T>(
+                    LogError(new JsonPatchError<T>(
+                        objectToApplyTo,
                         operation,
-                        Resources.FormatInvalidPathForArrayProperty(operation.op, operation.path),
+                        Resources.FormatInvalidPathForArrayProperty(operation.op, operation.path)));
-                        objectToApplyTo);
+
+                    return;
                 }
             }
             else
@@ -499,7 +547,10 @@ namespace Microsoft.AspNet.JsonPatch.Adapters
                 operation.value);
 
             // Is conversion successful
-            CheckIfPropertyCanBeSet(conversionResultTuple, objectToApplyTo, operation, operation.path);
+            if (!CheckIfPropertyCanBeSet(conversionResultTuple, objectToApplyTo, operation, operation.path))
+            {
+                return;
+            }
 
             //Compare
         }
@@ -571,7 +622,10 @@ namespace Microsoft.AspNet.JsonPatch.Adapters
                 .FindPropertyAndParent(objectToApplyTo, actualFromProperty, ContractResolver);
 
             // does property at from exist?
-            CheckIfPropertyExists(patchProperty, objectToApplyTo, operation, operation.from);
+            if (!CheckIfPropertyExists(patchProperty, objectToApplyTo, operation, operation.from))
+            {
+                return;
+            }
 
             // get the property path
             // is the path an array (but not a string (= char[]))?  In this case,
@@ -588,19 +642,24 @@ namespace Microsoft.AspNet.JsonPatch.Adapters
 
                     if (array.Count <= positionAsInteger)
                     {
-                        throw new JsonPatchException<T>(operation,
+                        LogError(new JsonPatchError<T>(
-                            Resources.FormatInvalidIndexForArrayProperty(operation.op, operation.from),
+                            objectToApplyTo,
-                            objectToApplyTo);
+                            operation,
+                            Resources.FormatInvalidIndexForArrayProperty(operation.op, operation.from)));
+
+                        return;
                     }
 
                     valueAtFromLocation = array[positionAsInteger];
                 }
                 else
                 {
-                    throw new JsonPatchException<T>(
+                    LogError(new JsonPatchError<T>(
+                        objectToApplyTo,
                         operation,
-                        Resources.FormatInvalidPathForArrayProperty(operation.op, operation.from),
+                        Resources.FormatInvalidPathForArrayProperty(operation.op, operation.from)));
-                        objectToApplyTo);
+
+                    return;
                 }
             }
             else
@@ -614,7 +673,7 @@ namespace Microsoft.AspNet.JsonPatch.Adapters
             Add(operation.path, valueAtFromLocation, objectToApplyTo, operation);
         }
 
-        private void CheckIfPropertyExists(
+        private bool CheckIfPropertyExists(
             JsonPatchProperty patchProperty,
             T objectToApplyTo,
             Operation<T> operation,
@@ -622,18 +681,25 @@ namespace Microsoft.AspNet.JsonPatch.Adapters
         {
             if (patchProperty == null)
             {
-                throw new JsonPatchException<T>(
+                LogError(new JsonPatchError<T>(
+                    objectToApplyTo,
                     operation,
-                    Resources.FormatPropertyDoesNotExist(propertyPath),
+                    Resources.FormatPropertyDoesNotExist(propertyPath)));
-                    objectToApplyTo);
+
+                return false;
             }
+
             if (patchProperty.Property.Ignored)
             {
-                throw new JsonPatchException<T>(
+                LogError(new JsonPatchError<T>(
+                    objectToApplyTo,
                     operation,
-                    Resources.FormatCannotUpdateProperty(propertyPath),
+                    Resources.FormatCannotUpdateProperty(propertyPath)));
-                    objectToApplyTo);
+
+                return false;
             }
+
+            return true;
         }
 
         private bool IsNonStringArray(JsonPatchProperty patchProperty)
@@ -643,7 +709,7 @@ namespace Microsoft.AspNet.JsonPatch.Adapters
                         patchProperty.Property.PropertyType.GetTypeInfo());
         }
 
-        private void CheckIfPropertyCanBeSet(
+        private bool CheckIfPropertyCanBeSet(
             ConversionResult result,
             T objectToApplyTo,
             Operation<T> operation,
@@ -651,10 +717,26 @@ namespace Microsoft.AspNet.JsonPatch.Adapters
         {
             if (!result.CanBeConverted)
             {
-                throw new JsonPatchException<T>(
+                LogError(new JsonPatchError<T>(
+                    objectToApplyTo,
                     operation,
-                    Resources.FormatInvalidValueForProperty(result.ConvertedInstance, path),
+                    Resources.FormatInvalidValueForProperty(result.ConvertedInstance, path)));
-                    objectToApplyTo);
+
+                return false;
+            }
+
+            return true;
+        }
+
+        private void LogError(JsonPatchError<T> jsonPatchError)
+        {
+            if (LogErrorAction != null)
+            {
+                LogErrorAction(jsonPatchError);
+            }
+            else
+            {
+                throw new JsonPatchException<T>(jsonPatchError);
             }
         }
     }

src/Microsoft.AspNet.JsonPatch/Exceptions/JsonPatchException.cs

@@ -26,15 +26,15 @@ namespace Microsoft.AspNet.JsonPatch.Exceptions
 
         }
 
-        public JsonPatchException(Operation<T> operation, string message, T affectedObject)
+        public JsonPatchException(JsonPatchError<T> jsonPatchError)
         {
-            FailedOperation = operation;
+            FailedOperation = jsonPatchError.Operation;
-            _message = message;
+            _message = jsonPatchError.ErrorMessage;
-            AffectedObject = affectedObject;
+            AffectedObject = jsonPatchError.AffectedObject;
         }
 
-        public JsonPatchException(Operation<T> operation, string message, T affectedObject, Exception innerException)
+        public JsonPatchException(JsonPatchError<T> jsonPatchError, Exception innerException)
-            : this(operation, message, affectedObject)
+            : this(jsonPatchError)
         {
             InnerException = innerException;
         }

src/Microsoft.AspNet.JsonPatch/JsonPatchError.cs

@@ -0,0 +1,45 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using Microsoft.AspNet.JsonPatch.Operations;
+using Microsoft.Framework.Internal;
+
+namespace Microsoft.AspNet.JsonPatch
+{
+    /// <summary>
+    /// Captures error message and the related entity and the operation that caused it.
+    /// </summary>
+    public class JsonPatchError<T> where T : class
+    {
+        /// <summary>
+        /// Initializes a new instance of <see cref="JsonPatchError{T}"/>.
+        /// </summary>
+        /// <param name="affectedObject">The object that is affected by the error.</param>
+        /// <param name="operation">The <see cref="Operation{T}"/> that caused the error.</param>
+        /// <param name="errorMessage">The error message.</param>
+        public JsonPatchError(
+            [NotNull] T affectedObject,
+            [NotNull] Operation<T> operation,
+            [NotNull] string errorMessage)
+        {
+            AffectedObject = affectedObject;
+            Operation = operation;
+            ErrorMessage = errorMessage;
+        }
+
+        /// <summary>
+        /// Gets the object that is affected by the error.
+        /// </summary>
+        public T AffectedObject { get; }
+
+        /// <summary>
+        /// Gets the <see cref="Operation{T}"/> that caused the error.
+        /// </summary>
+        public Operation<T> Operation { get; }
+
+        /// <summary>
+        /// Gets the error message.
+        /// </summary>
+        public string ErrorMessage { get; }
+    }
+}

src/Microsoft.AspNet.JsonPatch/TypedJsonPatchDocument.cs

@@ -354,12 +354,16 @@ namespace Microsoft.AspNet.JsonPatch
 
         public void ApplyTo(T objectToApplyTo)
         {
-            ApplyTo(objectToApplyTo, new ObjectAdapter<T>(ContractResolver));
+            ApplyTo(objectToApplyTo, new ObjectAdapter<T>(ContractResolver, logErrorAction: null));
+        }
+
+        public void ApplyTo(T objectToApplyTo, Action<JsonPatchError<T>> logErrorAction)
+        {
+            ApplyTo(objectToApplyTo, new ObjectAdapter<T>(ContractResolver, logErrorAction));
         }
 
         public void ApplyTo(T objectToApplyTo, IObjectAdapter<T> adapter)
         {
-
             // apply each operation in order
             foreach (var op in Operations)
             {

src/Microsoft.AspNet.Mvc/JsonPatchExtensions.cs

@@ -0,0 +1,51 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using Microsoft.AspNet.JsonPatch;
+using Microsoft.AspNet.Mvc.ModelBinding;
+using Microsoft.Framework.Internal;
+
+namespace Microsoft.AspNet.Mvc
+{
+    /// <summary>
+    /// Extensions for <see cref="JsonPatchDocument{T}"/>
+    /// </summary>
+    public static class JsonPatchExtensions
+    {
+        /// <summary>
+        /// Applies JSON patch operations on object and logs errors in <see cref="ModelStateDictionary"/>.
+        /// </summary>
+        /// <param name="patchDoc">The <see cref="JsonPatchDocument{T}"/>.</param>
+        /// <param name="objectToApplyTo">The entity on which <see cref="JsonPatchDocument{T}"/> is applied.</param>
+        /// <param name="modelState">The <see cref="ModelStateDictionary"/> to add errors.</param>
+        public static void ApplyTo<T>(
+            [NotNull] this JsonPatchDocument<T> patchDoc,
+            [NotNull] T objectToApplyTo,
+            [NotNull] ModelStateDictionary modelState) where T : class
+        {
+            patchDoc.ApplyTo(objectToApplyTo, modelState, prefix: string.Empty);
+        }
+
+        /// <summary>
+        /// Applies JSON patch operations on object and logs errors in <see cref="ModelStateDictionary"/>.
+        /// </summary>
+        /// <param name="patchDoc">The <see cref="JsonPatchDocument{T}"/>.</param>
+        /// <param name="objectToApplyTo">The entity on which <see cref="JsonPatchDocument{T}"/> is applied.</param>
+        /// <param name="modelState">The <see cref="ModelStateDictionary"/> to add errors.</param>
+        /// <param name="prefix">The prefix to use when looking up values in <see cref="ModelStateDictionary"/>.</param>
+        public static void ApplyTo<T>(
+            [NotNull] this JsonPatchDocument<T> patchDoc,
+            [NotNull] T objectToApplyTo,
+            [NotNull] ModelStateDictionary modelState,
+            string prefix) where T : class
+        {
+            patchDoc.ApplyTo(objectToApplyTo, jsonPatchError =>
+            {
+                var affectedObjectName = jsonPatchError.AffectedObject.GetType().Name;
+                var key = string.IsNullOrEmpty(prefix) ? affectedObjectName : prefix + "." + affectedObjectName;
+
+                modelState.TryAddModelError(key, jsonPatchError.ErrorMessage);
+            });
+        }
+    }
+}

test/Microsoft.AspNet.JsonPatch.Test/NestedObjectTests.cs

@@ -282,8 +282,10 @@ namespace Microsoft.AspNet.JsonPatch.Test
 
             // Act & Assert
             var exception = Assert.Throws<JsonPatchException<SimpleDTOWithNestedDTO>>(() => { patchDoc.ApplyTo(doc); });
-            Assert.Equal("For operation 'add' on array property at path '/simpledto/integerlist/4', the index is " +
+            Assert.Equal(
-                "larger than the array size.", exception.Message);
+                "For operation 'add' on array property at path '/simpledto/integerlist/4', the index is " +
+                    "larger than the array size.", 
+                exception.Message);
 
         }
 
@@ -311,8 +313,39 @@ namespace Microsoft.AspNet.JsonPatch.Test
                 {
                     deserialized.ApplyTo(doc);
                 });
-            Assert.Equal("For operation 'add' on array property at path '/simpledto/integerlist/4', the index is " +
+            Assert.Equal(
-                "larger than the array size.", exception.Message);
+                "For operation 'add' on array property at path '/simpledto/integerlist/4', the index is " +
+                    "larger than the array size.",
+                exception.Message);
+        }
+
+        [Fact]
+        public void AddToListInvalidPositionTooLarge_LogsError()
+        {
+            // Arrange
+            var doc = new SimpleDTOWithNestedDTO()
+            {
+                SimpleDTO = new SimpleDTO()
+                {
+                    IntegerList = new List<int>() { 1, 2, 3 }
+                }
+            };
+
+            // create patch
+            var patchDoc = new JsonPatchDocument<SimpleDTOWithNestedDTO>();
+            patchDoc.Add<int>(o => o.SimpleDTO.IntegerList, 4, 4);
+
+            var logger = new TestErrorLogger<SimpleDTOWithNestedDTO>();
+
+            // Act
+            patchDoc.ApplyTo(doc, logger.LogErrorMessage);
+
+            //Assert
+            Assert.Equal(
+                "For operation 'add' on array property at path '/simpledto/integerlist/4', the index is larger than " +
+                    "the array size.",
+                logger.ErrorMessage);
+
         }
 
         [Fact]
@@ -363,6 +396,31 @@ namespace Microsoft.AspNet.JsonPatch.Test
             Assert.Equal("Property does not exist at path '/simpledto/integerlist/-1'.", exception.Message);
         }
 
+        [Fact]
+        public void AddToListInvalidPositionTooSmall_LogsError()
+        {
+            // Arrange
+            var doc = new SimpleDTOWithNestedDTO()
+            {
+                SimpleDTO = new SimpleDTO()
+                {
+                    IntegerList = new List<int>() { 1, 2, 3 }
+                }
+            };
+
+            // create patch
+            var patchDoc = new JsonPatchDocument<SimpleDTOWithNestedDTO>();
+            patchDoc.Add<int>(o => o.SimpleDTO.IntegerList, 4, -1);
+
+            var logger = new TestErrorLogger<SimpleDTOWithNestedDTO>();
+
+            // Act
+            patchDoc.ApplyTo(doc, logger.LogErrorMessage);
+
+            //Assert
+            Assert.Equal("Property does not exist at path '/simpledto/integerlist/-1'.", logger.ErrorMessage);
+        }
+
         [Fact]
         public void AddToListAppend()
         {
@@ -528,8 +586,10 @@ namespace Microsoft.AspNet.JsonPatch.Test
 
             // Act & Assert
             var exception = Assert.Throws<JsonPatchException<SimpleDTOWithNestedDTO>>(() => { patchDoc.ApplyTo(doc); });
-            Assert.Equal("For operation 'remove' on array property at path '/simpledto/integerlist/3', the index is " +
+            Assert.Equal(
-                "larger than the array size.", exception.Message);
+                "For operation 'remove' on array property at path '/simpledto/integerlist/3', the index is " +
+                    "larger than the array size.",
+                exception.Message);
         }
 
         [Fact]
@@ -556,8 +616,38 @@ namespace Microsoft.AspNet.JsonPatch.Test
                 {
                     deserialized.ApplyTo(doc);
                 });
-            Assert.Equal("For operation 'remove' on array property at path '/simpledto/integerlist/3', the index is " +
+            Assert.Equal(
-                "larger than the array size.", exception.Message);
+                "For operation 'remove' on array property at path '/simpledto/integerlist/3', the index is " +
+                    "larger than the array size.",
+                exception.Message);
+        }
+
+        [Fact]
+        public void RemoveFromListInvalidPositionTooLarge_LogsError()
+        {
+            // Arrange
+            var doc = new SimpleDTOWithNestedDTO()
+            {
+                SimpleDTO = new SimpleDTO()
+                {
+                    IntegerList = new List<int>() { 1, 2, 3 }
+                }
+            };
+
+            // create patch
+            var patchDoc = new JsonPatchDocument<SimpleDTOWithNestedDTO>();
+            patchDoc.Remove<int>(o => o.SimpleDTO.IntegerList, 3);
+
+            var logger = new TestErrorLogger<SimpleDTOWithNestedDTO>();
+
+            // Act
+            patchDoc.ApplyTo(doc, logger.LogErrorMessage);
+
+            // Assert
+            Assert.Equal(
+                "For operation 'remove' on array property at path '/simpledto/integerlist/3', the index is " +
+                    "larger than the array size.",
+                logger.ErrorMessage);
         }
 
         [Fact]
@@ -608,6 +698,31 @@ namespace Microsoft.AspNet.JsonPatch.Test
             Assert.Equal("Property does not exist at path '/simpledto/integerlist/-1'.", exception.Message);
         }
 
+        [Fact]
+        public void RemoveFromListInvalidPositionTooSmall_LogsError()
+        {
+            // Arrange
+            var doc = new SimpleDTOWithNestedDTO()
+            {
+                SimpleDTO = new SimpleDTO()
+                {
+                    IntegerList = new List<int>() { 1, 2, 3 }
+                }
+            };
+
+            // create patch
+            var patchDoc = new JsonPatchDocument<SimpleDTOWithNestedDTO>();
+            patchDoc.Remove<int>(o => o.SimpleDTO.IntegerList, -1);
+
+            var logger = new TestErrorLogger<SimpleDTOWithNestedDTO>();
+
+            // Act
+            patchDoc.ApplyTo(doc, logger.LogErrorMessage);
+
+            // Assert
+            Assert.Equal("Property does not exist at path '/simpledto/integerlist/-1'.", logger.ErrorMessage);
+        }
+
         [Fact]
         public void RemoveFromEndOfList()
         {
@@ -1014,8 +1129,10 @@ namespace Microsoft.AspNet.JsonPatch.Test
 
             // Act & Assert
             var exception = Assert.Throws<JsonPatchException<SimpleDTOWithNestedDTO>>(() => { patchDoc.ApplyTo(doc); });
-            Assert.Equal("For operation 'replace' on array property at path '/simpledto/integerlist/3', the index is " +
+            Assert.Equal(
-                "larger than the array size.", exception.Message);
+                "For operation 'replace' on array property at path '/simpledto/integerlist/3', the index is " +
+                    "larger than the array size.",
+                exception.Message);
         }
 
         [Fact]
@@ -1042,8 +1159,38 @@ namespace Microsoft.AspNet.JsonPatch.Test
                 {
                     deserialized.ApplyTo(doc);
                 });
-            Assert.Equal("For operation 'replace' on array property at path '/simpledto/integerlist/3', the index is " +
+            Assert.Equal(
-                "larger than the array size.", exception.Message);
+                "For operation 'replace' on array property at path '/simpledto/integerlist/3', the index is " +
+                    "larger than the array size.",
+                exception.Message);
+        }
+
+        [Fact]
+        public void ReplaceInListInvalid_PositionTooLarge_LogsError()
+        {
+            // Arrange
+            var doc = new SimpleDTOWithNestedDTO()
+            {
+                SimpleDTO = new SimpleDTO()
+                {
+                    IntegerList = new List<int>() { 1, 2, 3 }
+                }
+            };
+
+            // create patch
+            var patchDoc = new JsonPatchDocument<SimpleDTOWithNestedDTO>();
+            patchDoc.Replace<int>(o => o.SimpleDTO.IntegerList, 5, 3);
+
+            var logger = new TestErrorLogger<SimpleDTOWithNestedDTO>();
+
+            // Act
+            patchDoc.ApplyTo(doc, logger.LogErrorMessage);
+
+            // Assert
+            Assert.Equal(
+                "For operation 'replace' on array property at path '/simpledto/integerlist/3', the index is " +
+                    "larger than the array size.",
+                logger.ErrorMessage);
         }
 
         [Fact]
@@ -1091,6 +1238,31 @@ namespace Microsoft.AspNet.JsonPatch.Test
             Assert.Equal("Property does not exist at path '/simpledto/integerlist/-1'.", exception.Message);
         }
 
+        [Fact]
+        public void ReplaceInListInvalidPositionTooSmall_LogsError()
+        {
+            // Arrange
+            var doc = new SimpleDTOWithNestedDTO()
+            {
+                SimpleDTO = new SimpleDTO()
+                {
+                    IntegerList = new List<int>() { 1, 2, 3 }
+                }
+            };
+
+            // create patch
+            var patchDoc = new JsonPatchDocument<SimpleDTOWithNestedDTO>();
+            patchDoc.Replace<int>(o => o.SimpleDTO.IntegerList, 5, -1);
+
+            var logger = new TestErrorLogger<SimpleDTOWithNestedDTO>();
+
+            // Act
+            patchDoc.ApplyTo(doc, logger.LogErrorMessage);
+
+            // Assert
+            Assert.Equal("Property does not exist at path '/simpledto/integerlist/-1'.", logger.ErrorMessage);
+        }
+
         [Fact]
         public void Copy()
         {

test/Microsoft.AspNet.JsonPatch.Test/ObjectAdapterTests.cs

@@ -113,8 +113,10 @@ namespace Microsoft.AspNet.JsonPatch.Test
 
             // Act & Assert
             var exception = Assert.Throws<JsonPatchException<SimpleDTO>>(() => { patchDoc.ApplyTo(doc); });
-            Assert.Equal("For operation 'add' on array property at path '/integerlist/4', the index is " +
+            Assert.Equal(
-                "larger than the array size.", exception.Message);
+                "For operation 'add' on array property at path '/integerlist/4', the index is " +
+                    "larger than the array size.",
+                exception.Message);
         }
 
         [Fact]
@@ -135,8 +137,35 @@ namespace Microsoft.AspNet.JsonPatch.Test
 
             // Act & Assert
             var exception = Assert.Throws<JsonPatchException<SimpleDTO>>(() => { deserialized.ApplyTo(doc); });
-            Assert.Equal("For operation 'add' on array property at path '/integerlist/4', the index is " +
+            Assert.Equal(
-                "larger than the array size.", exception.Message);
+                "For operation 'add' on array property at path '/integerlist/4', the index is " +
+                    "larger than the array size.",
+                exception.Message);
+        }
+
+        [Fact]
+        public void AddToListInvalidPositionTooLarge_LogsError()
+        {
+            // Arrange
+            var doc = new SimpleDTO()
+            {
+                IntegerList = new List<int>() { 1, 2, 3 }
+            };
+
+            // create patch
+            var patchDoc = new JsonPatchDocument<SimpleDTO>();
+            patchDoc.Add<int>(o => o.IntegerList, 4, 4);
+
+            var logger = new TestErrorLogger<SimpleDTO>();
+
+            // Act
+            patchDoc.ApplyTo(doc, logger.LogErrorMessage);
+
+            // Assert
+            Assert.Equal(
+                "For operation 'add' on array property at path '/integerlist/4', the index is " +
+                    "larger than the array size.",
+                logger.ErrorMessage);
         }
 
         [Fact]
@@ -264,6 +293,28 @@ namespace Microsoft.AspNet.JsonPatch.Test
             Assert.Equal("Property does not exist at path '/integerlist/-1'.", exception.Message);
         }
 
+        [Fact]
+        public void AddToListInvalidPositionTooSmall_LogsError()
+        {
+            // Arrange
+            var doc = new SimpleDTO()
+            {
+                IntegerList = new List<int>() { 1, 2, 3 }
+            };
+
+            // create patch
+            var patchDoc = new JsonPatchDocument<SimpleDTO>();
+            patchDoc.Add<int>(o => o.IntegerList, 4, -1);
+
+            var logger = new TestErrorLogger<SimpleDTO>();
+
+            // Act
+            patchDoc.ApplyTo(doc, logger.LogErrorMessage);
+
+            // Assert
+            Assert.Equal("Property does not exist at path '/integerlist/-1'.", logger.ErrorMessage);
+        }
+
         [Fact]
         public void AddToListAppend()
         {
@@ -408,8 +459,10 @@ namespace Microsoft.AspNet.JsonPatch.Test
 
             // Act & Assert
             var exception = Assert.Throws<JsonPatchException<SimpleDTO>>(() => { patchDoc.ApplyTo(doc); });
-            Assert.Equal("For operation 'remove' on array property at path '/integerlist/3', the index is " +
+            Assert.Equal(
-                "larger than the array size.", exception.Message);
+                "For operation 'remove' on array property at path '/integerlist/3', the index is " +
+                    "larger than the array size.",
+                exception.Message);
         }
 
         [Fact]
@@ -430,8 +483,35 @@ namespace Microsoft.AspNet.JsonPatch.Test
 
             // Act & Assert
             var exception = Assert.Throws<JsonPatchException<SimpleDTO>>(() => { deserialized.ApplyTo(doc); });
-            Assert.Equal("For operation 'remove' on array property at path '/integerlist/3', the index is " +
+            Assert.Equal(
-                "larger than the array size.", exception.Message);
+                "For operation 'remove' on array property at path '/integerlist/3', the index is " +
+                    "larger than the array size.",
+                exception.Message);
+        }
+
+        [Fact]
+        public void RemoveFromListInvalidPositionTooLarge_LogsError()
+        {
+            // Arrange
+            var doc = new SimpleDTO()
+            {
+                IntegerList = new List<int>() { 1, 2, 3 }
+            };
+
+            // create patch
+            var patchDoc = new JsonPatchDocument<SimpleDTO>();
+            patchDoc.Remove<int>(o => o.IntegerList, 3);
+
+            var logger = new TestErrorLogger<SimpleDTO>();
+
+            // Act
+            patchDoc.ApplyTo(doc, logger.LogErrorMessage);
+
+            // Assert
+            Assert.Equal(
+                "For operation 'remove' on array property at path '/integerlist/3', the index is " +
+                    "larger than the array size.",
+                logger.ErrorMessage);
         }
 
         [Fact]
@@ -473,6 +553,28 @@ namespace Microsoft.AspNet.JsonPatch.Test
             Assert.Equal("Property does not exist at path '/integerlist/-1'.", exception.Message);
         }
 
+        [Fact]
+        public void RemoveFromListInvalidPositionTooSmall_LogsError()
+        {
+            // Arrange
+            var doc = new SimpleDTO()
+            {
+                IntegerList = new List<int>() { 1, 2, 3 }
+            };
+
+            // create patch
+            var patchDoc = new JsonPatchDocument<SimpleDTO>();
+            patchDoc.Remove<int>(o => o.IntegerList, -1);
+
+            var logger = new TestErrorLogger<SimpleDTO>();
+
+            // Act
+            patchDoc.ApplyTo(doc, logger.LogErrorMessage);
+
+            // Assert
+            Assert.Equal("Property does not exist at path '/integerlist/-1'.", logger.ErrorMessage);
+        }
+
         [Fact]
         public void RemoveFromEndOfList()
         {
@@ -971,8 +1073,10 @@ namespace Microsoft.AspNet.JsonPatch.Test
             {
                 patchDoc.ApplyTo(doc);
             });
-            Assert.Equal("For operation 'replace' on array property at path '/integerlist/3', the index is " +
+            Assert.Equal(
-                "larger than the array size.", exception.Message);
+                "For operation 'replace' on array property at path '/integerlist/3', the index is " +
+                    "larger than the array size.",
+                exception.Message);
         }
 
         [Fact]
@@ -995,8 +1099,10 @@ namespace Microsoft.AspNet.JsonPatch.Test
             {
                 deserialized.ApplyTo(doc);
             });
-            Assert.Equal("For operation 'replace' on array property at path '/integerlist/3', the index is " +
+            Assert.Equal(
-                "larger than the array size.", exception.Message);
+                "For operation 'replace' on array property at path '/integerlist/3', the index is " +
+                    "larger than the array size.",
+                exception.Message);
         }
 
         [Fact]

test/Microsoft.AspNet.JsonPatch.Test/TestErrorLogger.cs

@@ -0,0 +1,15 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+namespace Microsoft.AspNet.JsonPatch.Test
+{
+    public class TestErrorLogger<T> where T: class
+    {
+        public string ErrorMessage { get; set; }
+
+        public void LogErrorMessage(JsonPatchError<T> patchError)
+        {
+            ErrorMessage = patchError.ErrorMessage;
+        }
+    }
+}

test/Microsoft.AspNet.Mvc.FunctionalTests/JsonPatchTest.cs

@@ -0,0 +1,145 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using System.Net.Http;
+using System.Text;
+using System.Threading.Tasks;
+using JsonPatchWebSite;
+using JsonPatchWebSite.Models;
+using Microsoft.AspNet.Builder;
+using Microsoft.Framework.DependencyInjection;
+using Newtonsoft.Json;
+using Xunit;
+
+namespace Microsoft.AspNet.Mvc.FunctionalTests
+{
+    public class JsonPatchTest
+    {
+        private const string SiteName = nameof(JsonPatchWebSite);
+        private readonly Action<IApplicationBuilder> _app = new Startup().Configure;
+        private readonly Action<IServiceCollection> _configureServices = new Startup().ConfigureServices;
+
+        [Theory]
+        [InlineData("http://localhost/jsonpatch/JsonPatchWithModelState")]
+        [InlineData("http://localhost/jsonpatch/JsonPatchWithModelStateAndPrefix?prefix=Patch")]
+        public async Task JsonPatch_ValidAddOperation_List(string url)
+        {
+            // Arrange
+            var server = TestHelper.CreateServer(_app, SiteName, _configureServices);
+            var client = server.CreateClient();
+
+            var input = "[{ \"op\": \"add\", \"path\": \"Customer/Orders/2\", " +
+               "\"value\": { \"OrderName\": \"Name2\" }}]";
+            var request = new HttpRequestMessage
+            {
+                Content = new StringContent(input, Encoding.UTF8, "application/json-patch+json"),
+                Method = new HttpMethod("PATCH"),
+                RequestUri = new Uri(url)
+            };
+
+            // Act
+            var response = await client.SendAsync(request);
+
+            // Assert
+            var body = await response.Content.ReadAsStringAsync();
+            var customer = JsonConvert.DeserializeObject<Customer>(body);
+            Assert.Equal("Name2", customer.Orders[2].OrderName);
+        }
+
+        [Theory]
+        [InlineData("http://localhost/jsonpatch/JsonPatchWithModelState")]
+        [InlineData("http://localhost/jsonpatch/JsonPatchWithModelStateAndPrefix?prefix=Patch")]
+        public async Task JsonPatch_MultipleValidOperations_Success(string url)
+        {
+            // Arrange
+            var server = TestHelper.CreateServer(_app, SiteName, _configureServices);
+            var client = server.CreateClient();
+
+            var input = "[{ \"op\": \"add\", \"path\": \"Customer/Orders/2\", " +
+               "\"value\": { \"OrderName\": \"Name2\" }}, {\"op\": \"copy\", \"from\": \"Customer/Orders/2\", " +
+                "\"path\": \"Customer/Orders/3\" }, {\"op\": \"replace\", \"path\": \"Customer/Orders/2/OrderName\", " +
+                "\"value\": \"ReplacedName\" }]";
+            var request = new HttpRequestMessage
+            {
+                Content = new StringContent(input, Encoding.UTF8, "application/json-patch+json"),
+                Method = new HttpMethod("PATCH"),
+                RequestUri = new Uri(url)
+            };
+
+            // Act
+            var response = await client.SendAsync(request);
+
+            // Assert
+            var body = await response.Content.ReadAsStringAsync();
+            var customer = JsonConvert.DeserializeObject<Customer>(body);
+            Assert.Equal("ReplacedName", customer.Orders[2].OrderName);
+            Assert.Equal("Name2", customer.Orders[3].OrderName);
+        }
+
+        public static IEnumerable<object[]> InvalidJsonPatchData
+        {
+            get
+            {
+                return new[]
+                {
+                    new object[] {
+                        "http://localhost/jsonpatch/JsonPatchWithModelStateAndPrefix?prefix=Patch",
+                        "[{ \"op\": \"add\", \"path\": \"Customer/Orders/5\", " +
+                        "\"value\": { \"OrderName\": \"Name5\" }}]",
+                        "{\"Patch.Customer\":[\"For operation 'add' on array property at path " +
+                        "'Customer/Orders/5', the index is larger than the array size.\"]}"
+                    },
+                    new object[] {
+                        "http://localhost/jsonpatch/JsonPatchWithModelState",
+                        "[{ \"op\": \"add\", \"path\": \"Customer/Orders/5\", " +
+                        "\"value\": { \"OrderName\": \"Name5\" }}]",
+                        "{\"Customer\":[\"For operation 'add' on array property at path " +
+                        "'Customer/Orders/5', the index is larger than the array size.\"]}"
+                    },
+                    new object[] {
+                        "http://localhost/jsonpatch/JsonPatchWithModelStateAndPrefix?prefix=Patch",
+                        "[{ \"op\": \"add\", \"path\": \"Customer/Orders/2\", \"value\": " +
+                        "{ \"OrderName\": \"Name2\" }}, {\"op\": \"copy\", \"from\": \"Customer/Orders/4\", " +
+                        "\"path\": \"Customer/Orders/3\" }, {\"op\": \"replace\", \"path\": " +
+                        "\"Customer/Orders/2/OrderName\", \"value\": \"ReplacedName\" }]",
+                        "{\"Patch.Customer\":[\"For operation 'copy' on array property at path " +
+                        "'Customer/Orders/4', the index is larger than the array size.\"]}"
+                    },
+                    new object[] {
+                        "http://localhost/jsonpatch/JsonPatchWithModelState",
+                        "[{ \"op\": \"add\", \"path\": \"Customer/Orders/2\", \"value\": " +
+                        "{ \"OrderName\": \"Name2\" }}, {\"op\": \"copy\", \"from\": \"Customer/Orders/4\", " +
+                        "\"path\": \"Customer/Orders/3\" }, {\"op\": \"replace\", \"path\": " +
+                        "\"Customer/Orders/2/OrderName\", \"value\": \"ReplacedName\" }]",
+                        "{\"Customer\":[\"For operation 'copy' on array property at path " +
+                        "'Customer/Orders/4', the index is larger than the array size.\"]}"
+                    }
+                };
+            }
+        }
+
+        [Theory, MemberData("InvalidJsonPatchData")]
+        public async Task JsonPatch_InvalidOperations_failure(string url, string input, string errorMessage)
+        {
+            // Arrange
+            var server = TestHelper.CreateServer(_app, SiteName, _configureServices);
+            var client = server.CreateClient();
+
+            var request = new HttpRequestMessage
+            {
+                Content = new StringContent(input, Encoding.UTF8, "application/json-patch+json"),
+                Method = new HttpMethod("PATCH"),
+                RequestUri = new Uri(url)
+            };
+
+            // Act
+            var response = await client.SendAsync(request);
+
+            // Assert
+            var body = await response.Content.ReadAsStringAsync();
+            Assert.Equal(errorMessage, body);
+        }
+    }
+}

test/Microsoft.AspNet.Mvc.FunctionalTests/project.json

@@ -28,6 +28,7 @@
         "FormatFilterWebSite": "1.0.0-*",
         "FormatterWebSite": "1.0.0",
         "InlineConstraintsWebSite": "1.0.0",
+        "JsonPatchWebSite": "1.0.0",
         "LoggingWebSite": "1.0.0",
         "LowercaseUrlsWebSite": "1.0.0-*",
         "Microsoft.AspNet.Mvc": "6.0.0-*",

test/Microsoft.AspNet.Mvc.Test/JsonPatchExtensionsTest.cs

@@ -0,0 +1,54 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using Microsoft.AspNet.JsonPatch;
+using Microsoft.AspNet.JsonPatch.Operations;
+using Microsoft.AspNet.Mvc.ModelBinding;
+using Xunit;
+
+namespace Microsoft.AspNet.Mvc
+{
+    public class JsonPatchExtensionsTest
+    {
+        [Fact]
+        public void ApplyTo_JsonPatchDocument_ModelState()
+        {
+            // Arrange
+            var operation = new Operation<Customer>("add", "Customer/CustomerId", from: null, value: "TestName");
+            var patchDoc = new JsonPatchDocument<Customer>();
+            patchDoc.Operations.Add(operation);
+
+            var modelState = new ModelStateDictionary();
+
+            // Act
+            patchDoc.ApplyTo(new Customer(), modelState);
+
+            // Assert
+            var error = Assert.Single(modelState["Customer"].Errors);
+            Assert.Equal("Property does not exist at path 'Customer/CustomerId'.", error.ErrorMessage);
+        }
+
+        [Fact]
+        public void ApplyTo_JsonPatchDocument_PrefixModelState()
+        {
+            // Arrange
+            var operation = new Operation<Customer>("add", "Customer/CustomerId", from: null, value: "TestName");
+            var patchDoc = new JsonPatchDocument<Customer>();
+            patchDoc.Operations.Add(operation);
+
+            var modelState = new ModelStateDictionary();
+
+            // Act
+            patchDoc.ApplyTo(new Customer(), modelState, "jsonpatch");
+
+            // Assert
+            var error = Assert.Single(modelState["jsonpatch.Customer"].Errors);
+            Assert.Equal("Property does not exist at path 'Customer/CustomerId'.", error.ErrorMessage);
+        }
+
+        public class Customer
+        {
+            public string CustomerName { get; set; }
+        }
+    }
+}

test/WebSites/JsonPatchWebSite/Controllers/JsonPatchController.cs

@@ -0,0 +1,65 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Collections.Generic;
+using JsonPatchWebSite.Models;
+using Microsoft.AspNet.JsonPatch;
+using Microsoft.AspNet.Mvc;
+
+namespace JsonPatchWebSite.Controllers
+{
+    [Route("jsonpatch/[action]")]
+    public class JsonPatchController : Controller
+    {
+        [HttpPatch]
+        public IActionResult JsonPatchWithModelState([FromBody] JsonPatchDocument<Customer> patchDoc)
+        {
+            var customer = CreateCustomer();
+
+            patchDoc.ApplyTo(customer, ModelState);
+
+            if (!ModelState.IsValid)
+            {
+                return HttpBadRequest(ModelState);
+            }
+
+            return new ObjectResult(customer);
+        }
+
+        [HttpPatch]
+        public IActionResult JsonPatchWithModelStateAndPrefix(
+            [FromBody] JsonPatchDocument<Customer> patchDoc,
+            string prefix)
+        {
+            var customer = CreateCustomer();
+
+            patchDoc.ApplyTo(customer, ModelState, prefix);
+
+            if (!ModelState.IsValid)
+            {
+                return HttpBadRequest(ModelState);
+            }
+
+            return new ObjectResult(customer);
+        }
+
+        private Customer CreateCustomer()
+        {
+            return new Customer
+            {
+                CustomerName = "John",
+                Orders = new List<Order>()
+                {
+                    new Order
+                    {
+                        OrderName = "Order1"
+                    },
+                    new Order
+                    {
+                        OrderName = "Order2"
+                    }
+                }
+            };
+        }
+    }
+}

test/WebSites/JsonPatchWebSite/JsonPatchWebSite.xproj

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="14.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <PropertyGroup>
+    <VisualStudioVersion Condition="'$(VisualStudioVersion)' == ''">14.0</VisualStudioVersion>
+    <VSToolsPath Condition="'$(VSToolsPath)' == ''">$(MSBuildExtensionsPath32)\Microsoft\VisualStudio\v$(VisualStudioVersion)</VSToolsPath>
+  </PropertyGroup>
+  <Import Project="$(VSToolsPath)\DNX\Microsoft.DNX.Props" Condition="'$(VSToolsPath)' != ''" />
+  <PropertyGroup Label="Globals">
+    <ProjectGuid>dab1252d-577c-4912-98be-1a812bf83f86</ProjectGuid>
+    <RootNamespace>JsonPatchWebSite</RootNamespace>
+    <BaseIntermediateOutputPath Condition="'$(BaseIntermediateOutputPath)'=='' ">..\..\..\artifacts\obj\$(MSBuildProjectName)</BaseIntermediateOutputPath>
+    <OutputPath Condition="'$(OutputPath)'=='' ">..\..\..\artifacts\bin\$(MSBuildProjectName)\</OutputPath>
+  </PropertyGroup>
+  <PropertyGroup>
+    <SchemaVersion>2.0</SchemaVersion>
+    <DevelopmentServerPort>29149</DevelopmentServerPort>
+  </PropertyGroup>
+  <Import Project="$(VSToolsPath)\DNX\Microsoft.DNX.targets" Condition="'$(VSToolsPath)' != ''" />
+</Project>

test/WebSites/JsonPatchWebSite/Models/Customer.cs

@@ -0,0 +1,14 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Collections.Generic;
+
+namespace JsonPatchWebSite.Models
+{
+    public class Customer
+    {
+        public string CustomerName { get; set; }
+
+        public List<Order> Orders { get; set; }
+    }
+}

test/WebSites/JsonPatchWebSite/Models/Order.cs

@@ -0,0 +1,10 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+namespace JsonPatchWebSite.Models
+{
+    public class Order
+    {
+        public string OrderName { get; set; }
+    }
+}

test/WebSites/JsonPatchWebSite/Startup.cs

@@ -0,0 +1,26 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using Microsoft.AspNet.Builder;
+using Microsoft.Framework.DependencyInjection;
+
+namespace JsonPatchWebSite
+{
+    public class Startup
+    {
+        // Set up application services
+        public void ConfigureServices(IServiceCollection services)
+        {
+            // Add MVC services to the services container
+            services.AddMvc();
+        }
+
+        public void Configure(IApplicationBuilder app)
+        {
+            app.UseCultureReplacer();
+
+            // Add MVC to the request pipeline
+            app.UseMvc();
+        }
+    }
+}

test/WebSites/JsonPatchWebSite/project.json

@@ -0,0 +1,19 @@
+{
+    "commands": {
+        "web": "Microsoft.AspNet.Hosting server=Microsoft.AspNet.Server.WebListener server.urls=http://localhost:5001",
+        "kestrel": "Microsoft.AspNet.Hosting --server Kestrel --server.urls http://localhost:5000"
+    },
+    "dependencies": {
+        "Kestrel": "1.0.0-*",
+        "Microsoft.AspNet.Mvc": "6.0.0-*",
+        "Microsoft.AspNet.Mvc.TestConfiguration": "1.0.0",
+        "Microsoft.AspNet.Server.IIS": "1.0.0-*",
+        "Microsoft.AspNet.Server.WebListener": "1.0.0-*",
+        "Microsoft.AspNet.StaticFiles": "1.0.0-*"
+    },
+    "frameworks": {
+        "dnx451": { },
+        "dnxcore50": { }
+    },
+    "webroot": "wwwroot"
+}

test/WebSites/JsonPatchWebSite/readme.md

@@ -0,0 +1,4 @@
+JsonPatchWebSite
+===
+
+This web site illustrates how to use JSON Patch operation on an object.

test/WebSites/JsonPatchWebSite/wwwroot/HelloWorld.htm

@@ -0,0 +1 @@
+HelloWorld