using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

​

namespace ConsoleApplication

{

    public class Program

    {

        public class City

        {

            public string Name { get; set; }

            public int Population { get; set; }

        }

​

        public class BaseClass

        {

            public int id { get; set; }

            public string Name { get; set; }

            public int Age { get; set; }

        }

​

        public class POCO : BaseClass

        {

            public City City1 { get; set; }

            public City City2 { get; set; }

            public City City3 { get; set; }

        }

​

        public class Normalized<T> : BaseClass

        {

            public List<T> City { get; set; }

​

            public static explicit operator Normalized<T>(POCO self)

            {

                if (self == null)

                    return null;

​

                var normal = new Normalized<T>();

​

                foreach (var prop in typeof(BaseClass).GetProperties())

                    prop.SetValue(normal, prop.GetValue(self));

​

                var complexProp = typeof(Normalized<T>).GetProperties().Where(x => x.PropertyType.GetInterfaces().Any(y => y.Name == "ICollection")).First();

                complexProp.SetValue(normal, new List<T>((typeof(POCO).GetProperties().Where(x => x.Name.Contains(complexProp.Name)).Select(x => (T)x.GetValue(self)).ToList())));

                return normal;

            }

        }

​

        public static void Main(string[] args)

        {

            var fromDB = new POCO

            {

                Age = 20,

                id = 1,

                Name = "Mike",

                City1 = new City { Name = "Moscow", Population = 10 },

                City2 = new City { Name = "London", Population = 20 },

                City3 = null

            };

            var normal = (Normalized<City>)fromDB;

            Console.WriteLine(normal.City.Select(x => x == null ? "EMPTY" : x.Name).Aggregate((a, b) => { return a + ", " + b; }));

        }

    }

}