using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Xml.Serialization;

using System.Xml;

using System.IO;

using System.Diagnostics;

using System.Collections.ObjectModel;

using System.Threading;

using System.ComponentModel;

using System.Xml.Linq;

using System.Reflection;

using System.Data;

using System.Xml.Schema;

using System.Text.RegularExpressions;

using System.Net;

using System.Xml.XPath;

using System.Globalization;

​

    // https://stackoverflow.com/questions/44234061/how-to-deserialize-xml-if-the-return-type-could-be-an-error-or-success-object

​

    public static partial class XmlSerializerExtensions

    {

        public static object DeserializePolymorphicXml(this string xml, params Type[] types)

        {

            using (var textReader = new StringReader(xml))

            {

                return textReader.DeserializePolymorphicXml(types);

            }

        }

​

        public static object DeserializePolymorphicXml(this TextReader textReader, params Type[] types)

        {

            if (textReader == null || types == null)

                throw new ArgumentNullException();

            var settings = new XmlReaderSettings { CloseInput = false }; // Let caller close the input.

            using (var xmlReader = XmlReader.Create(textReader, settings))

            {

                foreach (var type in types)

                {

                    var serializer = new XmlSerializer(type);

                    if (serializer.CanDeserialize(xmlReader))

                        return serializer.Deserialize(xmlReader);

                }

            }

            throw new XmlException("Invalid root type.");

        }

    }

​

    public static partial class XmlSerializerExtensions

    {

        public static string GetXml<T>(this T obj, bool omitStandardNamespaces)

        {

            XmlSerializerNamespaces ns = null;

            if (omitStandardNamespaces)

            {

                ns = new XmlSerializerNamespaces();

                ns.Add("", ""); // Disable the xmlns:xsi and xmlns:xsd lines.

            }

            using (var textWriter = new StringWriter())

            {

                var settings = new XmlWriterSettings() { Indent = true }; // For cosmetic purposes.

                using (var xmlWriter = XmlWriter.Create(textWriter, settings))

                    new XmlSerializer(obj.GetType()).Serialize(xmlWriter, obj, ns);

                return textWriter.ToString();

            }

        }

    }

​

    public class SuccessResponse

    {

        public string Value { get; set; }

    }

​

    public class FailResponse

    {

        public string Message { get; set; }

    }

​

    public class TestClass

    {

        public static void Test()

        {

            Test(new SuccessResponse { Value = "my value" }.GetXml(true));

            Test(new FailResponse { Message = "failure message" }.GetXml(true));

​

            Console.WriteLine("Done");

        }

​

        public static void Test(string xml)

        {

            Console.WriteLine("Input XML: ");

            Console.WriteLine(xml);

​

            var xmlBody = xml.DeserializePolymorphicXml(typeof(SuccessResponse), typeof(FailResponse));

            Console.WriteLine(string.Format("Deserialized response of type: {0}", xmlBody.GetType()));

            if (xmlBody is SuccessResponse)

            {

                // Handle successful response

                Console.WriteLine(string.Format("Successful response, Value = {0}", ((SuccessResponse)xmlBody).Value));

            }

            else if (xmlBody is FailResponse)

            {

                // Handle failed response

                Console.WriteLine(string.Format("Failure response, Message = {0}", ((FailResponse)xmlBody).Message));

            }

            else

            {

                // unknown response

                throw new InvalidOperationException("unknown response");

            }

            Console.WriteLine("Re-serialized XML: ");

            Console.WriteLine(xmlBody.GetXml(true));

            Console.WriteLine("");

        }

    }

    public class Program

    {

        public static void Main()

        {

            Console.WriteLine("Environment version: " + Environment.Version);

            Console.WriteLine("");

            TestClass.Test();

        }

    }