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 DataRowConverter : JsonConverter<DataRow>

    {

        public override DataRow ReadJson(JsonReader reader, Type objectType, DataRow existingValue, bool hasExistingValue, JsonSerializer serializer)

        {

            throw new NotImplementedException(string.Format("{0} is only implemented for writing.", this));

        }

​

        public override void WriteJson(JsonWriter writer, DataRow row, JsonSerializer serializer)

        {

            var table = row.Table;

            if (table == null)

                throw new JsonSerializationException("no table");

            var contractResolver = serializer.ContractResolver as DefaultContractResolver;

​

            writer.WriteStartObject();

            foreach (DataColumn col in row.Table.Columns)

            {

                var value = row[col];

​

                if (serializer.NullValueHandling == NullValueHandling.Ignore && (value == null || value == DBNull.Value))

                    continue;

                writer.WritePropertyName(contractResolver != null ? contractResolver.GetResolvedPropertyName(col.ColumnName) : col.ColumnName);

                serializer.Serialize(writer, value);

            }

            writer.WriteEndObject();

        }

    }

​

    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);    

​

            row = table.NewRow();

​

            row["America"] = null;

            row["Africa"] = JsonConvert.DeserializeObject<Place>(@"{""Id"":13,""Title"":""EG""}");

            row["Japan"] = null;

            table.Rows.Add(row);    

​

            return table;

        }

​

        public static void Test()

        {

            var datatable = MakeTable();

​

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

            {

                var row = datatable.Rows[rowIndex];

                var settings = new JsonSerializerSettings

                {

                    Converters = { new DataRowConverter() },

                    // Add other settings as required, e.g.

                    NullValueHandling = NullValueHandling.Ignore,

​

                };

                var rowJson = JsonConvert.SerializeObject(row, Formatting.Indented, settings);

​

                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;

            }

        }

    }

​