Fix for issue #29 (Honor JsonProperty when serializing a JsonPatchDocument) (#35)

* Fix for issue #29 (Honor JsonProperty when serializing a JsonPatchDocument)

src/Microsoft.AspNetCore.JsonPatch/Helpers/ExpressionHelpers.cs

@@ -1,9 +1,12 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using Newtonsoft.Json;
 using System;
 using System.Globalization;
+using System.Linq;
 using System.Linq.Expressions;
+using System.Reflection;
 
 namespace Microsoft.AspNetCore.JsonPatch.Helpers
 {
@@ -51,11 +54,13 @@ namespace Microsoft.AspNetCore.JsonPatch.Helpers
                     if (ContinueWithSubPath(memberExpression.Expression.NodeType, false))
                     {
                         var left = GetPath(memberExpression.Expression, false);
-                        return left + "/" + memberExpression.Member.Name;
+                        // Get property name, respecting JsonProperty attribute
+                        return left + "/" + GetPropertyNameFromMemberExpression(memberExpression);
                     }
                     else
                     {
-                        return memberExpression.Member.Name;
+                        // Get property name, respecting JsonProperty attribute                       
+                        return GetPropertyNameFromMemberExpression(memberExpression);
                     }
                 case ExpressionType.Parameter:
                     // Fits "x => x" (the whole document which is "" as JSON pointer)
@@ -65,6 +70,23 @@ namespace Microsoft.AspNetCore.JsonPatch.Helpers
             }
         }
 
+        private static string GetPropertyNameFromMemberExpression(MemberExpression memberExpression)
+        {
+            // if there's a JsonProperty attribute, we must return the PropertyName
+            // from the attribute rather than the member name 
+            var jsonPropertyAttribute =
+                memberExpression.Member.GetCustomAttribute(
+                typeof(JsonPropertyAttribute), true);
+
+            if (jsonPropertyAttribute == null)
+            {
+                return memberExpression.Member.Name;
+            }
+            // get value
+            var castedAttribute = (JsonPropertyAttribute)jsonPropertyAttribute;
+            return castedAttribute.PropertyName;
+        }
+
         private static bool ContinueWithSubPath(ExpressionType expressionType, bool firstTime)
         {
             if (firstTime)

test/Microsoft.AspNetCore.JsonPatch.Test/JsonPatchDocumentJsonPropertyAttributeTest.cs

@@ -0,0 +1,148 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using Newtonsoft.Json;
+using System.Linq;
+using Xunit;
+
+namespace Microsoft.AspNetCore.JsonPatch
+{
+    public class JsonPatchDocumentJsonPropertyAttributeTest
+    {
+        [Fact]
+        public void Add_WithExpression_RespectsJsonPropertyName_ForModelProperty()
+        {
+            var patchDoc = new JsonPatchDocument<JsonPropertyDTO>();
+            patchDoc.Add(p => p.Name, "John");
+
+            var serialized = JsonConvert.SerializeObject(patchDoc);
+            // serialized value should have "AnotherName" as path
+            // deserialize to a JsonPatchDocument<JsonPropertyWithAnotherNameDTO> to check
+            var deserialized =
+                JsonConvert.DeserializeObject<JsonPatchDocument<JsonPropertyWithAnotherNameDTO>>(serialized);
+
+            // get path
+            var pathToCheck = deserialized.Operations.First().path;
+            Assert.Equal(pathToCheck, "/anothername");
+        }
+
+        [Fact]
+        public void Add_WithExpression_RespectsJsonPropertyName_WhenApplyingToDifferentlyTypedClassWithPropertyMatchingJsonPropertyName()
+        {
+            var patchDocToSerialize = new JsonPatchDocument<JsonPropertyDTO>();
+            patchDocToSerialize.Add(p => p.Name, "John");
+
+            // the patchdoc will deserialize to "anothername".  We should thus be able to apply 
+            // it to a class that HAS that other property name.
+            var doc = new JsonPropertyWithAnotherNameDTO()
+            {
+                AnotherName = "InitialValue"
+            };
+
+            var serialized = JsonConvert.SerializeObject(patchDocToSerialize);
+            var deserialized =
+                JsonConvert.DeserializeObject<JsonPatchDocument<JsonPropertyWithAnotherNameDTO>>
+                (serialized);
+
+            deserialized.ApplyTo(doc);
+
+            Assert.Equal(doc.AnotherName, "John");
+        }
+
+        [Fact]
+        public void Add_WithExpression_RespectsJsonPropertyName_WhenApplyingToSameTypedClassWithMatchingJsonPropertyName()
+        {
+            var patchDocToSerialize = new JsonPatchDocument<JsonPropertyDTO>();
+            patchDocToSerialize.Add(p => p.Name, "John");
+
+            // the patchdoc will deserialize to "anothername".  As JsonPropertyDTO has
+            // a JsonProperty signifying that "Name" should be deseriallized from "AnotherName",
+            // we should be able to apply the patchDoc.
+
+            var doc = new JsonPropertyDTO()
+            {
+                Name = "InitialValue"
+            };
+
+            var serialized = JsonConvert.SerializeObject(patchDocToSerialize);
+            var deserialized =
+                JsonConvert.DeserializeObject<JsonPatchDocument<JsonPropertyDTO>>
+                (serialized);
+
+            deserialized.ApplyTo(doc);
+
+            Assert.Equal(doc.Name, "John");
+        }
+
+        [Fact]
+        public void Add_OnApplyFromJson_RespectsJsonPropertyNameOnJsonDocument()
+        {
+            var doc = new JsonPropertyDTO()
+            {
+                Name = "InitialValue"
+            };
+            
+            // serialization should serialize to "AnotherName"
+            var serialized = "[{\"value\":\"Kevin\",\"path\":\"/AnotherName\",\"op\":\"add\"}]";
+            var deserialized =
+                JsonConvert.DeserializeObject<JsonPatchDocument<JsonPropertyDTO>>(serialized);
+
+            deserialized.ApplyTo(doc);
+
+            Assert.Equal("Kevin", doc.Name);
+        }
+
+        [Fact]
+        public void Remove_OnApplyFromJson_RespectsJsonPropertyNameOnJsonDocument()
+        {
+            var doc = new JsonPropertyDTO()
+            {
+                Name = "InitialValue"
+            };
+
+            // serialization should serialize to "AnotherName"
+            var serialized = "[{\"path\":\"/AnotherName\",\"op\":\"remove\"}]";
+            var deserialized =
+                JsonConvert.DeserializeObject<JsonPatchDocument<JsonPropertyDTO>>(serialized);
+
+            deserialized.ApplyTo(doc);
+
+            Assert.Equal(null, doc.Name);
+        }
+
+        [Fact]
+        public void Add_OnApplyFromJson_RespectsInheritedJsonPropertyNameOnJsonDocument()
+        {
+            var doc = new JsonPropertyWithInheritanceDTO()
+            {
+                Name = "InitialName"
+            };
+
+            // serialization should serialize to "AnotherName"
+            var serialized = "[{\"value\":\"Kevin\",\"path\":\"/AnotherName\",\"op\":\"add\"}]";
+            var deserialized =
+                JsonConvert.DeserializeObject<JsonPatchDocument<JsonPropertyWithInheritanceDTO>>(serialized);
+
+            deserialized.ApplyTo(doc);
+
+            Assert.Equal("Kevin", doc.Name);
+        }
+
+        [Fact]
+        public void Add_WithExpression_RespectsJsonPropertyName_ForInheritedModelProperty()
+        {
+            var patchDoc = new JsonPatchDocument<JsonPropertyWithInheritanceDTO>();
+            patchDoc.Add(p => p.Name, "John");
+
+            var serialized = JsonConvert.SerializeObject(patchDoc);
+            // serialized value should have "AnotherName" as path
+            // deserialize to a JsonPatchDocument<JsonPropertyWithAnotherNameDTO> to check
+            var deserialized =
+                JsonConvert.DeserializeObject<JsonPatchDocument<JsonPropertyWithAnotherNameDTO>>(serialized);
+
+            // get path
+            var pathToCheck = deserialized.Operations.First().path;
+            Assert.Equal(pathToCheck, "/anothername");
+        }
+    }
+}

test/Microsoft.AspNetCore.JsonPatch.Test/JsonPropertyDTO.cs

@@ -0,0 +1,13 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using Newtonsoft.Json;
+
+namespace Microsoft.AspNetCore.JsonPatch
+{
+    public class JsonPropertyDTO
+    {
+        [JsonProperty("AnotherName")]
+        public string Name { get; set; }
+    }
+}

test/Microsoft.AspNetCore.JsonPatch.Test/JsonPropertyWithAnotherNameDTO.cs

@@ -0,0 +1,10 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+namespace Microsoft.AspNetCore.JsonPatch
+{
+    public class JsonPropertyWithAnotherNameDTO
+    {
+        public string AnotherName { get; set; }
+    }
+}

test/Microsoft.AspNetCore.JsonPatch.Test/JsonPropertyWithInheritanceDTO.cs

@@ -0,0 +1,19 @@
+using Newtonsoft.Json;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace Microsoft.AspNetCore.JsonPatch
+{
+    public class JsonPropertyWithInheritanceDTO : JsonPropertyWithInheritanceBaseDTO
+    {
+        public override string Name { get; set; }
+    }
+
+    public abstract class JsonPropertyWithInheritanceBaseDTO
+    {
+        [JsonProperty("AnotherName")]
+        public abstract string Name { get; set; }
+    }
+}