using System;

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Reflection;

public class Program

{

    public static void Main()

    {

        var p1 = new Person(){ Id = 1, FirstName = "Thanh", Roles = new List<string>(){ "Thanh1" }, Group = new Group(){ Name = "Group1" } };

        var p2 = new Person(){ Id = 1, LastName = "Truong Duc", Roles = new List<string>(){ "User" }, Group = new Group(){ Id = 1 } };

        object p3;

        MergeObject(p1, p2, out p3, typeof(Person));

        Console.WriteLine(JsonConvert.SerializeObject(p3));

        Console.WriteLine(((Person)p3).FirstName);

    }

    private static void MergeObject(object obj1, object obj2, out object obj, Type type)

        {

        Console.WriteLine(JsonConvert.SerializeObject(obj1));

                            Console.WriteLine(JsonConvert.SerializeObject(obj2));

            var properties = type.GetProperties().Where(x=>x.CanWrite).ToList();

            Console.WriteLine(JsonConvert.SerializeObject(properties.Select(x=>x.PropertyType.FullName).ToList()));

            var objDefault = Activator.CreateInstance(type);

            obj = Activator.CreateInstance(type);

            foreach (var prop in properties)

            {

                var propValueDefault = prop.GetValue(objDefault);

                var propValue = prop.GetValue(obj1);

                Console.WriteLine(typeof(IEnumerable).IsAssignableFrom(prop.PropertyType));

                if(propValue == null){

                    propValue = prop.GetValue(obj2);

                }else if(isCollection(prop)) // check prop is a collection

                {

                    Console.WriteLine("ok");

                    var propObj2Value = prop.GetValue(obj2) as IList;

                    if (propObj2Value != null)

                    {

                        if (propValue == null){

                            propValue = propObj2Value;

                        }else{

                            Console.WriteLine(JsonConvert.SerializeObject(propObj2Value));

                            Console.WriteLine(JsonConvert.SerializeObject(propValue));

                            foreach (var item in propObj2Value)

                            {

                                (propValue as IList).Add(item);

                            }

                        }

                        Console.WriteLine(JsonConvert.SerializeObject(propValue));

                    }

                }else if(isChildClass(prop)){

                    Console.WriteLine("class" + prop.PropertyType);

                    var propObj2Value = prop.GetValue(obj2);

                    if(propObj2Value != null){

                        MergeObject(propValue, propObj2Value, out propValue, prop.PropertyType);

                    }

                }

                else

                {

                    if(propValue.Equals(propValueDefault))

                    {

                        Console.WriteLine("default: " + propValueDefault);

                        propValue = prop.GetValue(obj2);

                    }

                }

                prop.SetValue(obj, propValue);

            }

        }

        private static bool isCollection(PropertyInfo propertyInfo)

        {

            return propertyInfo.PropertyType != typeof(string) && typeof(IEnumerable).IsAssignableFrom(propertyInfo.PropertyType);

        }

        private static bool isChildClass(PropertyInfo propertyInfo)

        {

            return (propertyInfo.PropertyType.IsClass && !propertyInfo.PropertyType.IsValueType &&

                                !propertyInfo.PropertyType.IsPrimitive && propertyInfo.PropertyType.FullName != "System.String");

        }

}

​

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; }

    public List<string> Roles {get;set;}

    public Group Group{get;set;}

    public Person(){}

}

​

public class Group{

    public int Id {get;set;}

    public string Name{ get;set;}

    public Group(){}

}

​

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;

    }

}