using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Data;

​

using System.Text.Json;

using System.Text.Json.Serialization;

using System.Text.Json.Nodes;

​

using Newtonsoft.Json.Linq;

​

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

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//https://stackoverflow.com/questions/66495660/net-5-0-signature-change-of-system-text-json-jsonserializer-deserialize

​

#nullable enable

​

    class TestClass

    {

        public static void Test()

        {

            Test("myKey");

            Console.WriteLine();

            Test("myMissingKey");

        }

        static void Test(string myKey)

        {

            var newtonsoftString = TestNewtonsoft(GetJson(), myKey);

            Console.WriteLine("Newtonsoft result for key {0}: {1}", myKey, newtonsoftString);

​

            var systemString = QueryJson(GetJson(), myKey, true);

            Console.WriteLine("System.Text.Json.Nodes result for key {0}: {1}", myKey, systemString);

​

            var docString = QueryJsonWithJsonDocument(GetJson(), myKey, true);

            Console.WriteLine("JsonDocument result for key {0}: {1}", myKey, docString);

            Assert.AreEqual(newtonsoftString, QueryJson(GetJson(), myKey, true));

            Assert.AreEqual(newtonsoftString, QueryJsonWithJsonDocument(GetJson(), myKey, true));

        }   

        static string? QueryJson(string json, string myKey, bool addComma = false)

        {

            // Parse to a JsonNode and cast to JsonObject.  An exception is thrown if not an object

            var node = JsonNode.Parse(json)!.AsObject(); 

            // Query the array of strings

            var query = (node[myKey] as JsonArray)?.Select(i => i?.ToString().ToUpper());

            if (query == null)

                return null; // Return null if key not found as per original code

            if (addComma)

                query = query.Concat(new [] { "" });

​

            // Join the string array into a single comma-separated string

            return string.Join(',', query);

        }

​

        static string? QueryJsonWithJsonDocument(string json, string myKey, bool addComma = false)

        {

            // Parse to a JsonNode and cast to JsonObject.  An exception is thrown if not an object

            using var doc = JsonDocument.Parse(json);

​

            // Query the array of strings

            var query = doc.RootElement.Get(myKey)?.EnumerateArray().Select(e => e.GetString()?.ToUpper());

            if (query == null)

                return null; // Return null if key not found as per original code

            if (addComma)

                query = query.Concat(new [] { "" });

​

            // Join the string array into a single comma-separated string

            return string.Join(',', query);

        }

        static string TestNewtonsoft(string json, string myKey)

        {

            string myList = null!;

            object jsonObject = Newtonsoft.Json.JsonConvert.DeserializeObject(json, typeof(object));

​

            // Loop through the keys

            foreach (var jsonList in ((Newtonsoft.Json.Linq.JObject)(jsonObject)))

            {                   

                if (jsonList.Key == myKey)

                {                       

                    foreach (object o in (jsonList.Value.ToArray()))

                    {                           

                        myList += o.ToString().ToUpper() + ',';

                    }

                }

            }

            return myList;

        }

        static string GetJson() => @"{""myKey"":[""fir"",""dsdsd""],""status"":""ok""}";

    }

​

    //https://stackoverflow.com/a/61561343/3744182

​

    public static partial class JsonExtensions

    {

        public static JsonElement? Get(this JsonElement element, string name) => 

            element.ValueKind != JsonValueKind.Null && element.ValueKind != JsonValueKind.Undefined && element.TryGetProperty(name, out var value) 

                ? value : (JsonElement?)null;

    }

​

    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("System.Text.Json version: " + typeof(JsonSerializer).Assembly.FullName);

            Console.WriteLine();

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            try

            {

                TestClass.Test();

            }

            catch (Exception ex)

            {

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

                Console.WriteLine(ex);

                throw;

            }

        }

    }

​