using System;

using System.Collections;

using System.Collections.Generic;

using Newtonsoft.Json;

public class Program

{

    public static void Main()

    {

        FooCollection coll = new FooCollection();

        coll.Add(new Foo { Id = 1, Name = "Moe" });

        coll.Add(new Foo { Id = 2, Name = "Larry" });

        coll.Add(new Foo { Id = 3, Name = "Curly" });

​

        JsonSerializerSettings settings = new JsonSerializerSettings();

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

        settings.Formatting = Newtonsoft.Json.Formatting.Indented;

​

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

​

        Console.WriteLine(json);

    }

}

​

class Foo

{

    public int Id { get; set; }

    public string Name { get; set; }

}

​

class FooCollection : IEnumerable<Foo>

{

    private List<Foo> list = new List<Foo>();

​

    public void Add(Foo foo)

    {

        list.Add(foo);

    }

​

    public Foo this[string name]

    {

        get { return list.Find(f => f.Name == name); }

    }

​

    public IEnumerator<Foo> GetEnumerator()

    {

        return list.GetEnumerator();

    }

​

    IEnumerator IEnumerable.GetEnumerator()

    {

        return ((IEnumerable)list).GetEnumerator();

    }

}

​

class FooCollectionConverter : JsonConverter

{

    public override bool CanConvert(Type objectType)

    {

        return (objectType == typeof(FooCollection));

    }

​

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

    {

        writer.WriteStartObject();

        foreach (Foo foo in (FooCollection)value)

        {

            writer.WritePropertyName(GetFooKey(foo));

            serializer.Serialize(writer, foo);

        }

        writer.WriteEndObject();

    }

​

    // Given a Foo, return its unique key to be used during serialization

    private string GetFooKey(Foo foo)

    {

        return foo.Name;

    }

    public override bool CanRead

    {

        get { return false; }

    }

​

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

    {

        throw new NotImplementedException();

    }

}