using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Runtime.Serialization.Formatters;

using System.IO;

using System.Data;

using System.ComponentModel.DataAnnotations;

using System.Globalization;

using System.Reflection;

​

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using Newtonsoft.Json.Converters;

using Newtonsoft.Json.Serialization;    

​

using NUnit.Framework; // Throws NUnit.Framework.AssertionException

​

//https://stackoverflow.com/questions/33399749/convert-a-data-row-to-a-json-object/33400729#33400729

​

    public class TestClass

    {

        static DataTable MakeTable()

        {

            var table = new DataTable();

​

            table.Columns.Add("America", typeof(Place));

            table.Columns.Add("Africa", typeof(Place));

            table.Columns.Add("Japan", typeof(Place));

​

            DataRow row = table.NewRow();

​

            row["America"] = JsonConvert.DeserializeObject<Place>(@"{""Id"":1,""Title"":""Ka""}");

            row["Africa"] = JsonConvert.DeserializeObject<Place>(@"{""Id"":2,""Title"":""Sf""}");

            row["Japan"] = JsonConvert.DeserializeObject<Place>(@"{""Id"":3,""Title"":""Ja"",""Values"":{""ValID"":4,""Type"":""Okinawa""}}");

            table.Rows.Add(row);    

​

            row = table.NewRow();

​

            row["America"] = JsonConvert.DeserializeObject<Place>(@"{""Id"":4,""Title"":""CT""}");

            row["Africa"] = JsonConvert.DeserializeObject<Place>(@"{""Id"":5,""Title"":""SA""}");

            row["Japan"] = JsonConvert.DeserializeObject<Place>(@"{""Id"":6,""Title"":""Ja"",""Values"":{""ValID"":4,""Type"":""Tokyo""}}");

            table.Rows.Add(row);    

​

            return table;

​

        }

​

        public static void Test()

        {

            var datatable = MakeTable();

​

            for (int rowIndex = 0; rowIndex < datatable.Rows.Count; rowIndex++)

            {

                var jArray = JArray.FromObject(datatable, JsonSerializer.CreateDefault(new JsonSerializerSettings { NullValueHandling = NullValueHandling.Ignore }));

                var rowJToken = jArray[rowIndex];

                var rowJson = rowJToken.ToString(Formatting.Indented);  // Or Formatting.None if you prefer

​

                Console.WriteLine("JSON for row {0}:", rowIndex);

                Console.WriteLine(rowJson);

            }

        }

    }

​

    public class Values

    {

        public int ValID { get; set; }

        public string Type { get; set; }

    }

​

    public class Place

    {

        public int Id { get; set; }

        public string Title { get; set; }

        public Values Values { get; set; }

    }

​

    public class Program

    {

        public static void Main()

        {

            Console.WriteLine("Environment version: " + Environment.Version);

            Console.WriteLine("Json.NET version: " + typeof(JsonSerializer).Assembly.FullName);

            Console.WriteLine();

​

            try

            {

                TestClass.Test();

            }

            catch (Exception ex)

            {

                Console.WriteLine("Failed with unhandled exception: ");

                Console.WriteLine(ex);

                throw;

            }

        }

    }

​