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.ComponentModel.DataAnnotations;

using System.Globalization;

using System.Xml;

using System.Data.DataSetExtensions;

​

namespace Test

{

    using Newtonsoft.Json;

    using System.Data; //(in System.Data.DataSetExtensions.dll)

​

    // https://stackoverflow.com/questions/48137342/how-to-convert-the-following-data-from-dataset-in-json-object-in-c-sharp

    class TestClass

    {

        public static void Test()

        {

            var dataTable = MakeTable();

​

            // Choose the property name and value keys.

            var propertyKey = "Block";

            var valuesKey = "HouseNo";

​

            // Generate the Dictionary<string, string []>

            var dictionary = dataTable.AsEnumerable()

                // Generate a grouping of all houses for each block

                .GroupBy(r => r.Field<string>(propertyKey), r => r.Field<string>(valuesKey))

                // And convert to a dictionary of names and array values for JSON serialization.

                .ToDictionary(g => propertyKey + " " + g.Key, g => g.ToArray());

​

            // Now serialize to JSON with your preferred serializer.  Mine is Json.NET

            var json = JsonConvert.SerializeObject(dictionary, Formatting.Indented);

​

            Console.WriteLine("\nOutput JSON:");

            Console.WriteLine(json);

​

            Console.WriteLine("\nInput DataTable was:");

            Console.WriteLine(JsonConvert.SerializeObject(dataTable, Formatting.Indented));

        }

​

        static DataTable MakeTable()

        {

            var data = new[]

                {

                    new [] { "A", "101" },

                    new [] { "A", "102" },

                    new [] { "A", "103" },

                    new [] { "B", "101" },

                    new [] { "B", "102" },

                    new [] { "B", "104" },

                };

​

            var dt = new DataTable();

​

            dt.Columns.Add(new DataColumn("Block", typeof(string)));

            dt.Columns.Add(new DataColumn("HouseNo", typeof(string)));

​

            foreach (var line in data)

            {

                var row = dt.NewRow();

                row["Block"] = line[0];

                row["HouseNo"] = line[1];

                dt.Rows.Add(row);

            }

            return dt;

        }

    }

    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;

            }

        }

    }

​

    public class AssertionFailedException : System.Exception

    {

        public AssertionFailedException() : base() { }

​

        public AssertionFailedException(string s) : base(s) { }

    }

​

    public static class Assert

    {

        public static void IsTrue(bool value)

        {

            IsTrue(value, "failed");

        }

​

        public static void IsTrue(bool value, string message)

        {

            if (value == false)

                throw new AssertionFailedException(message ?? "failed");

        }

    }

}

​

​