using System;

using System.Collections.Generic;

using Newtonsoft.Json;

using Newtonsoft.Json.Serialization;

using Newtonsoft.Json.Linq;

using System.Reflection;

public class Program

{

    public static void Main(string[] args)

    {

        Zoo hardcodedZoo = new Zoo()

        {

            Name = "My Zoo",

            Animals = new List<IAnimal> 

            { 

                new Dog("Ruff"), 

                new Cat("Cleo"),

                new Dog("Rover")

                {

                    Children = new List<IAnimal>

                    { 

                        new Dog("Fido"), 

                        new Dog("Fluffy")

                    }

                }

            }

        };

        JsonSerializerSettings settings = new JsonSerializerSettings()

        {

            ContractResolver = new CamelCasePropertyNamesContractResolver(),

            Formatting = Formatting.Indented

        };

        settings.Converters.Add(new AnimalsConverter());

        string json = JsonConvert.SerializeObject(hardcodedZoo, settings);

        Console.Write(json);

    }

}

class Zoo

{

    public string Name { get; set; }

    public List<IAnimal> Animals { get; set; }

}

​

public interface IAnimal

{

    string Name { get; set; }

    string Speak();

    List<IAnimal> Children { get; set; }

}

​

public class Cat : IAnimal

{

    public string Name { get; set; }

    public List<IAnimal> Children { get; set; }

    public Cat()

    {

        Children = new List<IAnimal>();

    }

    public Cat(string name = "") : this()

    {

        Name = name;

    }

    public string Speak()

    {

        return "Meow";

    }

}

​

public class Dog : IAnimal

{

    public string Name { get; set; }

    public List<IAnimal> Children { get; set; }

    public Dog()

    {

        Children = new List<IAnimal>();

    }

    public Dog(string name = "") : this()

    {

        Name = name;

    }

    public string Speak()

    {

        return "Arf";

    }

}

​

class AnimalsConverter : JsonConverter

{

    public override bool CanConvert(Type objectType)

    {

        return (typeof(IAnimal).IsAssignableFrom(objectType));

    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)

    {

        throw new NotImplementedException();

    }

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)

    {

        JObject jo = new JObject();

        Type type = value.GetType();

        jo.Add("type", type.Name);

        foreach (PropertyInfo prop in type.GetProperties())

        {

            if (prop.CanRead)

            {

                object propVal = prop.GetValue(value, null);

                if (propVal != null)

                {

                    jo.Add(prop.Name, JToken.FromObject(propVal, serializer));

                }

            }

        }

        jo.WriteTo(writer);

    }

}

​

​

​