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 System.Xml.Linq;

​

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

​

//https://stackoverflow.com/questions/56260418/how-to-convert-from-huge-json-file-to-xml-file-in-c-sharp?noredirect=1#comment99157984_56260418

​

    public static partial class JsonExtensions

    {

        public static XDocument LoadXNode(string pathJson, string deserializeRootElementName)

        {

            using (var stream = File.OpenRead(pathJson))

                return LoadXNode(stream, deserializeRootElementName);

        }

​

        public static XDocument LoadXNode(Stream stream, string deserializeRootElementName)

        {

            // Let caller dispose the underlying streams.

            using (var textReader = new StreamReader(stream, Encoding.UTF8, true, 1024, true))

                return LoadXNode(textReader, deserializeRootElementName);

        }

​

        public static XDocument LoadXNode(TextReader textReader, string deserializeRootElementName)

        {

            var settings = new JsonSerializerSettings 

            { 

                Converters = { new XmlNodeConverter { DeserializeRootElementName = deserializeRootElementName } },

            };

            using (var jsonReader = new JsonTextReader(textReader) { CloseInput = false })

                return JsonSerializer.CreateDefault(settings).Deserialize<XDocument>(jsonReader);

        }

​

        public static void StreamJsonToXml(string pathJson, string pathXml, string deserializeRootElementName, SaveOptions saveOptions = SaveOptions.None)

        {

            var doc = LoadXNode(pathJson, deserializeRootElementName);

            doc.Save(pathXml, saveOptions);

        }

    }

​

    class TestClass

    {

        public static void Test()

        {

            var pathJson = "Question56260418.json";

            var outputPath = "Question56260418.xml";

            try

            {

                File.WriteAllText(pathJson, GetJson());

                JsonExtensions.StreamJsonToXml(pathJson, outputPath, "json");

                Assert.IsTrue(File.Exists(outputPath));

                Console.WriteLine(File.ReadAllText(outputPath));

            }

            finally

            {

                File.Delete(pathJson);

                File.Delete(outputPath);

            }

        }   

        static string GetJson()

        {

            var json = @"{""Root"": [

  {

    ""Name"": ""Jonh "",

    ""Order"": [

      {

        ""Product"": {

          ""Id"": 8

        },

        ""Quantity"": 1

      },

      {

        ""Product"": {

          ""Id"": 19

        },

        ""Quantity"": 8

      },

      {

        ""Product"": {

          ""Id"": 26

        },

        ""Quantity"": 7

      }

    ]

  },

  {

    ""Name"": ""Jane Doe 1"",

    ""Order"": [

      {

        ""Product"": {

          ""Id"": 26

        },

        ""Quantity"": 7

      },

      {

        ""Product"": {

          ""Id"": 44

        },

        ""Quantity"": 2

      },

      {

        ""Product"": {

          ""Id"": 21

        },

        ""Quantity"": 6

      },

      {

        ""Product"": {

          ""Id"": 48

        },

        ""Quantity"": 2

      },

      {

        ""Product"": {

          ""Id"": 35

        },

        ""Quantity"": 2

      },

      {

        ""Product"": {

          ""Id"": 43

        },

        ""Quantity"": 1

      }

    ]

  }

]}";

            return json;

        }   

    }

​

    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;

            }

        }

    }

​