using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.IO;

using System.Data;

using System.Globalization;

​

using System.Runtime.Serialization.Json;

using System.Runtime.Serialization;

​

​

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/76482804/json-datacontract-dual-types-for-string-and-string-array

​

    [DataContract]

    public class Response

    {

        [IgnoreDataMember]

        public string [] Messages { get; set; }

        [DataMember(Name = "message")]

        object SerializedMessages 

        { 

            get => Messages; 

            set => Messages = (value) switch

            {

                null => null,

                string s => new [] { s },

                string [] a => a,

                // Convert arrays of primitives to strings

                object [] a => a.Cast<IFormattable>().Select(f => Convert.ToString(f, CultureInfo.InvariantCulture)).ToArray(),

                _ => throw new ArgumentException(string.Format("Unknown value type {0}", value)),

            };

        }

    }

​

    class TestClass

    {

        public static void Test()

        {

            foreach (var json in GetJson())

            {

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

                Console.WriteLine(json);

                var response = DataContractJsonSerializerHelper.FromContractJson<Response>(json);

​

                Console.WriteLine("Result:");

                var newJson = JsonConvert.SerializeObject(response, Formatting.Indented);

​

                Console.WriteLine(newJson);

            }

        }   

        static IEnumerable<string> GetJson() =>

        new [] 

        {

            """

            {

              "message": "Hello World."

            }

            """,

            """

            {

              "message": [

                "Hello World.",

                "Hello StackOverflow."

              ]

            }

            """,

        };

    }

​

    public static partial class DataContractJsonSerializerHelper

    {

        private static MemoryStream GenerateStreamFromString(string value)

        {

            return new MemoryStream(Encoding.UTF8.GetBytes(value ?? ""));

        }

​

        public static string ToContractJson<T>(this T obj, DataContractJsonSerializer serializer = null)

        {

            serializer = serializer ?? new DataContractJsonSerializer(obj == null ? typeof(T) : obj.GetType());

            using (var memory = new MemoryStream())

            {

                serializer.WriteObject(memory, obj);

                memory.Seek(0, SeekOrigin.Begin);

                using (var reader = new StreamReader(memory))

                {

                    return reader.ReadToEnd();

                }

            }

        }

​

        public static T FromContractJson<T>(string json, DataContractJsonSerializer serializer = null)

        {

            serializer = serializer ?? new DataContractJsonSerializer(typeof(T));

            using (var stream = GenerateStreamFromString(json))

            {

                var obj = serializer.ReadObject(stream);

                return (T)obj;

            }

        }

    }

​

    public static partial class DataContractJsonSerializerHelper

    {

        public static T FromContractJson<T>(string json, DataContractJsonSerializerSettings settings) =>

            FromContractJson<T>(json, new DataContractJsonSerializer(typeof(T), settings));

​

        public static string ToContractJson<T>(T obj, DataContractJsonSerializerSettings settings) => 

            ToContractJson<T>(obj, new DataContractJsonSerializer(obj.GetType(), settings));

    }

​

​

    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;

            }

        }

    }

​