using System;

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

public class Program

{

    public static void Main()

    {

        var p = new Person()

        {

            Id = 123,

            FirstName = "John",

            LastName = "Doe",

            Address1 = "456 Main St",

            Address2 = "Apt 2"

        };

        string json = JsonConvert.SerializeObject(p);

        Console.WriteLine(json);

        Console.WriteLine();

        Console.WriteLine();

        Person p2 = JsonConvert.DeserializeObject<Person>(json);

        Console.WriteLine("Id: " + p2.Id);

        Console.WriteLine("FirstName: " + p2.FirstName);

        Console.WriteLine("LastName: " + p2.LastName);

        Console.WriteLine("Address1: " + p2.Address1);

        Console.WriteLine("Address2: " + p2.Address2);

    }

}

​

[JsonConverter(typeof(PersonConverter))]

public class Person 

{

    public int Id { get; set; }

    public string FirstName { get; set; }

    public string LastName { get; set; }

    public string Address1 { get; set; }

    public string Address2 { get; set; }

}

​

class PersonConverter : JsonConverter

{

    public override bool CanConvert(Type objectType)

    {

        return objectType == typeof(Person);

    }

​

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

    {

        Person person = (Person)value;

        JObject result = new JObject();

        result.Add("id", person.Id);

        result.Add("fullname", (person.FirstName + " " + person.LastName).Trim());

        result.Add("address", (person.Address1 + " " + person.Address2).Trim());

        result.WriteTo(writer);

    }

​

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

    {

        JObject obj = JObject.Load(reader);

        Person person = new Person();

        person.Id = (int)obj["id"];   // assuming id will always be present in the JSON

        string fullName = (string)obj["fullname"];

        if (fullName != null)

        {

            string[] parts = fullName.Split(new char[] { ' ' }, 2);

            // if there's only 1 part, I'm assuming it is the first name

            if (parts.Length > 0)

                person.FirstName = parts[0];

            if (parts.Length > 1)

                person.LastName = parts[1];

        }

        person.Address1 = (string)obj["address"];  // don't bother trying to split address

        return person;

    }

}