using System;

using System.Collections.Generic;

using System.Data;

using System.Dynamic;

using Newtonsoft.Json;

public class Program

{

    public static void Main()

    {

           var dt = new DataTable();

            dt.Columns.Add("ID", typeof(int));

            dt.Columns.Add("username", typeof(string));

            dt.Rows.Add(1, "Name1");

            dt.Rows.Add(2, "Name2");

            dt.Rows.Add(3, "Name3");

            dt.Rows.Add(4, "Name4");

            dt.Rows.Add(5, "Name5");

            List<dynamic> dynamicDt = dt.ToDynamic();

​

            //If username is exact column name

            var usernamevalue = dynamicDt[1].username;

            string JSONresult;

            JSONresult = JsonConvert.SerializeObject(dt);  

            Console.WriteLine(JSONresult);

            Console.WriteLine(usernamevalue);

            Console.WriteLine(dynamicDt[0]);

    }

}

 public static class DataTableExtensions

    {

        public static List<dynamic> ToDynamic(this DataTable dt)

        {

            var dynamicDt = new List<dynamic>();

            foreach (DataRow row in dt.Rows)

            {

                dynamic dyn = new ExpandoObject();

                dynamicDt.Add(dyn);

                foreach (DataColumn column in dt.Columns)

                {

                    var dic = (IDictionary<string, object>)dyn;

                    dic[column.ColumnName] = row[column];

                }

            }

            return dynamicDt;

        }

     }

​

​

​