using System;

using System.Collections.Generic;

using System.Text;

using System.Linq;

using System.Xml.Serialization;

using System.Xml;

using System.Xml.Linq;

using System.IO;

using System.Data;

using System.Runtime.Serialization;

using System.Runtime.Serialization.Formatters.Binary;

using System.IO.Compression;

using System.Reflection;

​

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

​

//https://stackoverflow.com/questions/73407255/getting-error-while-parsing-the-null-value-in-xml-file-extrate-using-c-sharp

​

#nullable enable

​

    public static class XNodeExtensions

    {

        static readonly XNamespace xsi = @"http://www.w3.org/2001/XMLSchema-instance";

        static readonly XName xsiNil = xsi + "nil";

        public static bool IsNull(this XElement? element) => element == null || element.Attribute(xsiNil)?.Value == "true";

    }

​

    namespace XMLFileUploader

    {

        public static class ExtractLogFile

        {

            public static void ExtractData(string filePath)

            {

                XElement root = XElement.Load(filePath);

                IEnumerable<XElement> tests =

                                     from el in root.Elements("measList") 

                                     select el;

​

                IEnumerable<XElement> measList =

                  from el2 in tests.Elements("Measurement")

                  select el2;

​

                foreach (XElement el2 in measList)

                {

                    Measurement mes = new Measurement();

​

                    if (el2.NodeType == XmlNodeType.Element && el2.Name == "Measurement")

                    {

                        mes.MeasurementInfoGuid = (String)el2.Element("MeasurementGuid");

                        mes.SequenceNumber = (int)el2.Element("SequenceNumber");

                        mes.Time = (DateTime)el2.Element("Time");

                        var sensorBlobVersionElement = el2.Element("SensorBlobVersion");

                        if (sensorBlobVersionElement == null)

                            mes.SensorBlobVersion = 0; // Element was missing, assign to 0

                        else if (sensorBlobVersionElement.IsNull()) 

                            mes.SensorBlobVersion = null; // Element was present but explicitly null

                        else

                            mes.SensorBlobVersion = (int?)(sensorBlobVersionElement);

                        mes.Dump();

                    }

                }

            }

​

            public class Measurement

            {

                public String MeasurementInfoGuid { get; set; }

                public int SequenceNumber { get; set; }

                public DateTime Time { get; set; }

                public int? SensorBlobVersion { get; set; }

            }

​

        }

    }

​

    public class TestClass

    {

        public static void Test()

        {

            string fileName = "Question73407255.xml";

            File.WriteAllText(fileName, GetXml());

            try

            {

                XMLFileUploader.ExtractLogFile.ExtractData(fileName);

            }

            finally

            {

                File.Delete(fileName);

            }

        }

        static string GetXml() => @"<XMLList xmlns:xsi=""http://www.w3.org/2001/XMLSchema-instance"" xmlns:xsd=""http://www.w3.org/2001/XMLSchema"">

  <measList>

    <Measurement>

      <MeasurementGuid>17ae41e0-e9ec-4570-83c1-75fbfc96db17</MeasurementGuid>   

      <SequenceNumber>953</SequenceNumber>

      <Time>2020-10-07T15:39:06</Time>

      <SensorBlobVersion xsi:nil=""true"" />     

    </Measurement>

    <Measurement>

      <MeasurementGuid>27ae41e0-e9ec-4570-83c1-75fbfc96db17</MeasurementGuid>   

      <SequenceNumber>953</SequenceNumber>

      <Time>2020-10-07T15:39:06</Time>

    </Measurement>

    <Measurement>

      <MeasurementGuid>3243234-e9ec-2324-83c1-43fbfc96db17</MeasurementGuid>   

      <SequenceNumber>111</SequenceNumber>

      <Time>2022-11-07T15:39:06</Time>

      <SensorBlobVersion>101</SensorBlobVersion>

    </Measurement>

​

 </measList>

</XMLList>

​

";

    }

​

    public class Program

    {

        public static void Main()

        {

            Console.WriteLine("Environment version: {0} ({1}, {2})", System.Runtime.InteropServices.RuntimeInformation.FrameworkDescription , Environment.Version, Environment.OSVersion);

            Console.WriteLine();

​

            try

            {

                TestClass.Test();

            }

            catch (Exception ex)

            {

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

                Console.WriteLine(ex);

                throw;

            }

        }

    }

​