Add Contract and Property Parameters to JsonConverter

Src/Newtonsoft.Json.Tests/Converters/JsonConverter2Tests.cs

@@ -0,0 +1,146 @@
+using System;
+using System.Collections.Generic;
+using Newtonsoft.Json.Serialization;
+using Newtonsoft.Json.Utilities;
+#if DNXCORE50
+using Xunit;
+using Test = Xunit.FactAttribute;
+using Assert = Newtonsoft.Json.Tests.XUnitAssert;
+#else
+using NUnit.Framework;
+
+#endif
+
+namespace Newtonsoft.Json.Tests.Converters
+{
+    public class JsonConverter2Tests
+    {
+        [Test]
+        public void SerializeCollectionWithDifferentSubTypesWithTypeNameHandlingAuto()
+        {
+            var contacts = new List<ContactModelBase>();
+            var c1 = new ContactWithUSAddressModel();
+            c1.FullName = "John Doe";
+            c1.StreetAddress = "123 Main St";
+            c1.City = "New York";
+            c1.State = "New York";
+            c1.ZipCode = "12345";
+            c1.Country = "United States";
+
+            var c2 = new ContactWithCanadianAddressModel();
+            c2.FullName = "Jane Doe";
+            c2.StreetAddress = "123 Main St";
+            c2.City = "Toronto";
+            c2.Province = "Ontario";
+            c2.PostalCode = "J4K3N5";
+            c2.Country = "Canada";
+
+            var c3 = new ContactModelBase();
+            c3.FullName = "FullName";
+            c3.StreetAddress = "StreetAddress";
+            c3.City = "CityName";
+            c3.Country = "CountryName";
+
+            contacts.Add(c1);
+            contacts.Add(c2);
+            contacts.Add(c3);
+
+            var jsonActual = JsonConvert.SerializeObject(contacts, new JsonSerializerSettings
+            {
+                Converters = new List<JsonConverter>
+                {
+                    new ContactConverter()
+                },
+                TypeNameHandling = TypeNameHandling.Auto
+            });
+
+            var jsonExpected = JsonConvert.SerializeObject(contacts, new JsonSerializerSettings
+            {
+                TypeNameHandling = TypeNameHandling.Auto
+            });
+
+            StringAssert.AreEqual(jsonExpected, jsonActual);
+        }
+
+        public class ContactModelBase
+        {
+            public string FullName { get; set; }
+            public string StreetAddress { get; set; }
+            public string City { get; set; }
+            public string Country { get; set; }
+        }
+
+        public class ContactWithUSAddressModel : ContactModelBase
+        {
+            public string ZipCode { get; set; }
+            public string State { get; set; }
+        }
+
+        public class ContactWithCanadianAddressModel : ContactModelBase
+        {
+            public string PostalCode { get; set; }
+            public string Province { get; set; }
+        }
+
+        public class ContactConverter : JsonConverter2
+        {
+            public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
+            {
+                throw new NotSupportedException();
+            }
+
+            public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
+            {
+                throw new NotSupportedException();
+            }
+
+            public override bool CanConvert(Type objectType)
+            {
+                return objectType.IsSubclassOf(typeof(ContactModelBase));
+            }
+
+            public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer, JsonContract contract, JsonContainerContract collectionContract, JsonProperty containerProperty)
+            {
+                writer.WriteStartObject();
+                if (collectionContract.ItemContract.UnderlyingType != value.GetType())
+                {
+                    writer.WritePropertyName("$type");
+                    writer.WriteValue(ReflectionUtils.GetTypeName(value.GetType(), serializer.TypeNameAssemblyFormatHandling, serializer.SerializationBinder));
+                }
+
+                if (value is ContactWithUSAddressModel usContact)
+                {
+                    writer.WritePropertyName(nameof(ContactWithUSAddressModel.ZipCode));
+                    serializer.Serialize(writer, usContact.ZipCode);
+                    writer.WritePropertyName(nameof(ContactWithUSAddressModel.State));
+                    serializer.Serialize(writer, usContact.State);
+                    writer.WritePropertyName(nameof(ContactModelBase.FullName));
+                    serializer.Serialize(writer, usContact.FullName);
+                    writer.WritePropertyName(nameof(ContactModelBase.StreetAddress));
+                    serializer.Serialize(writer, usContact.StreetAddress);
+                    writer.WritePropertyName(nameof(ContactModelBase.City));
+                    serializer.Serialize(writer, usContact.City);
+                    writer.WritePropertyName(nameof(ContactModelBase.Country));
+                    serializer.Serialize(writer, usContact.Country);
+                }
+                else if (value is ContactWithCanadianAddressModel canContact)
+                {
+                    writer.WritePropertyName(nameof(ContactWithCanadianAddressModel.PostalCode));
+                    serializer.Serialize(writer, canContact.PostalCode);
+                    writer.WritePropertyName(nameof(ContactWithCanadianAddressModel.Province));
+                    serializer.Serialize(writer, canContact.Province);
+                    writer.WritePropertyName(nameof(ContactModelBase.FullName));
+                    serializer.Serialize(writer, canContact.FullName);
+                    writer.WritePropertyName(nameof(ContactModelBase.StreetAddress));
+                    serializer.Serialize(writer, canContact.StreetAddress);
+                    writer.WritePropertyName(nameof(ContactModelBase.City));
+                    serializer.Serialize(writer, canContact.City);
+                    writer.WritePropertyName(nameof(ContactModelBase.Country));
+                    serializer.Serialize(writer, canContact.Country);
+                }
+
+                writer.WriteEndObject();
+            }
+        }
+    }
+}

Src/Newtonsoft.Json/JsonConverter.cs

@@ -28,6 +28,7 @@
 using System.Globalization;
 using System.Runtime.CompilerServices;
 using System.Diagnostics.CodeAnalysis;
+using Newtonsoft.Json.Serialization;
 
 namespace Newtonsoft.Json
 {
@@ -146,4 +147,21 @@ public sealed override bool CanConvert(Type objectType)
             return typeof(T).IsAssignableFrom(objectType);
         }
     }
+
+    /// <summary>
+    /// Converts an object to and from JSON.
+    /// </summary>
+    public abstract class JsonConverter2 : JsonConverter
+    {
+        /// <summary>
+        /// Writes the JSON representation of the object.
+        /// </summary>
+        /// <param name="writer">The <see cref="JsonWriter"/> to write to.</param>
+        /// <param name="value">The value.</param>
+        /// <param name="serializer">The calling serializer.</param>
+        /// <param name="contract">Contract of the current value</param>
+        /// <param name="collectionContract">Contract of the parent container</param>
+        /// <param name="containerProperty">JsonProperty of the container property field</param>
+        public abstract void WriteJson(JsonWriter writer, object? value, JsonSerializer serializer, JsonContract contract, JsonContainerContract? collectionContract, JsonProperty? containerProperty);
+    }
 }

Src/Newtonsoft.Json/Serialization/JsonSerializerInternalWriter.cs

@@ -679,7 +679,14 @@ private void SerializeConvertable(JsonWriter writer, JsonConverter converter, ob
                     TraceWriter.Trace(TraceLevel.Info, JsonPosition.FormatMessage(null, writer.Path, "Started serializing {0} with converter {1}.".FormatWith(CultureInfo.InvariantCulture, value.GetType(), converter.GetType())), null);
                 }
 
-                converter.WriteJson(writer, value, GetInternalSerializer());
+                if (converter is JsonConverter2 converter2)
+                {
+                    converter2.WriteJson(writer, value, GetInternalSerializer(), contract, collectionContract, containerProperty);    
+                }
+                else
+                {
+                    converter.WriteJson(writer, value, GetInternalSerializer());
+                }
 
                 if (TraceWriter != null && TraceWriter.LevelFilter >= TraceLevel.Info)
                 {