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

CSharp · Console

/Program.cs

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;
			}
		}
	}