using System;

using System.Linq;

using System.Collections.Generic;

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

public class Program

{

    public static void Main()

    {

        var obj = new MyObject

        {

            DictionaryProperty = new Dictionary<(EnumType1,EnumType2),string>

            {

                [(EnumType1.EnumType1Value1,EnumType2.EnumType2Value1)] = "New",

                [(EnumType1.EnumType1Value2,EnumType2.EnumType2Value2)] = "Old"

            }

        };

        var json = JsonConvert.SerializeObject(obj);

        Console.WriteLine(json);

        var obj2 = JsonConvert.DeserializeObject<MyObject>(json);

        foreach(var kv in obj2.DictionaryProperty)

        {

            Console.WriteLine($"{kv.Key.ToString()}={kv.Value}");

        }

    }

}

​

public class CustomDictionaryConverter : JsonConverter<Dictionary<(EnumType1 Enum1, EnumType2 Enum2), string>>

{

    public override void WriteJson(JsonWriter writer, Dictionary<(EnumType1 Enum1, EnumType2 Enum2), string> value, JsonSerializer serializer)

    {

        writer.WriteStartObject();

        foreach(var kv in value)

        {

            writer.WritePropertyName($"({kv.Key.Enum1.ToString()},{kv.Key.Enum2.ToString()})");

            writer.WriteValue(kv.Value);

        }

        writer.WriteEndObject();

    }

​

    public override Dictionary<(EnumType1 Enum1, EnumType2 Enum2), string> ReadJson(

        JsonReader reader

        , Type objectType

        , Dictionary<(EnumType1 Enum1, EnumType2 Enum2), string> existingValue

        , bool hasExistingValue

        , JsonSerializer serializer)

    {

        Dictionary<(EnumType1 Enum1, EnumType2 Enum2), string> tempdict = new Dictionary<(EnumType1 Enum1, EnumType2 Enum2), string>();

        JObject jObject = JObject.Load(reader);

        foreach(var kv in ((IEnumerable<KeyValuePair<string, JToken>>)jObject)) 

        {

            var keys = kv.Key.Replace("(","").Replace(")","").Split(",");

            var key1 = Enum.Parse<EnumType1>(keys[0]);

            var key2 = Enum.Parse<EnumType2>(keys[1]);

            var value = kv.Value.ToString();

            tempdict.Add((key1,key2),value);

        }

        return tempdict;

    }

}

​

public class MyObject 

{

    [JsonConverter(typeof(CustomDictionaryConverter))]

    public Dictionary<(EnumType1,EnumType2),string> DictionaryProperty{get;set;}

}

​

public enum EnumType1

{

    EnumType1Value1,

    EnumType1Value2

}

public enum EnumType2

{

    EnumType2Value1,

    EnumType2Value2

}