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

​

//https://stackoverflow.com/questions/58501943/how-to-make-json-serialize-ignore-dictionary-keys

​

    public class RootObject

    {

        [JsonConverter(typeof(VerbatimDictionaryConverter<string, string>))]

        public IDictionary<string, string> CustomAttributes { get; set; }       

    }

​

    public class VerbatimDictionaryConverter<TKey, TValue> : JsonConverter<IDictionary<TKey, TValue>>

    {

        [JsonDictionary(NamingStrategyType = typeof(DefaultNamingStrategy))]

        class VerbatimDictionarySerializationSurrogate : IReadOnlyDictionary<TKey, TValue>

        {

            readonly IDictionary<TKey, TValue> dictionary;

​

            public VerbatimDictionarySerializationSurrogate(IDictionary<TKey, TValue> dictionary) 

            { 

                if (dictionary == null) 

                    throw new ArgumentNullException(nameof(dictionary));

                this.dictionary = dictionary; 

            }

            public bool ContainsKey(TKey key) { return dictionary.ContainsKey(key); }

            public bool TryGetValue(TKey key, out TValue value) { return dictionary.TryGetValue(key, out value); }

            public TValue this[TKey key] { get { return dictionary[key]; } }

            public IEnumerable<TKey> Keys { get { return dictionary.Keys; } }

            public IEnumerable<TValue> Values { get { return dictionary.Values; } }

            public int Count { get { return dictionary.Count; } }

            public IEnumerator<KeyValuePair<TKey, TValue>> GetEnumerator() { return dictionary.GetEnumerator(); }

            IEnumerator IEnumerable.GetEnumerator() { return GetEnumerator(); }

        }

​

        public override void WriteJson(JsonWriter writer, IDictionary<TKey, TValue> value, JsonSerializer serializer)

        {

            serializer.Serialize(writer, new VerbatimDictionarySerializationSurrogate(value));

        }

​

        public override bool CanRead { get { return false; } }

        public override IDictionary<TKey, TValue> ReadJson(JsonReader reader, Type objectType, IDictionary<TKey, TValue> existingValue, bool hasExistingValue, JsonSerializer serializer) { throw new NotImplementedException(); }

    }

    class TestClass

    {

        public static void Test()

        {

            var root = new RootObject

            {

                CustomAttributes = new Dictionary<string, string>()

                {

                    {"Custom Attribute 1", "1"},

                    {"CustomAttribute 2", "2"}

                }

            };

            var settings = new JsonSerializerSettings

            {

                ContractResolver = new CamelCasePropertyNamesContractResolver(),

            };

            var json = JsonConvert.SerializeObject(root, Formatting.Indented, settings);

            Console.WriteLine(json);

​

            Assert.IsTrue(((JObject)JToken.Parse(json)["customAttributes"]).Properties().Select(p => p.Name).SequenceEqual(root.CustomAttributes.Keys));

            Assert.IsTrue(JsonConvert.DeserializeObject<RootObject>(json, settings).CustomAttributes.Keys.SequenceEqual(root.CustomAttributes.Keys));

        }   

    }

​

    public class Program

    {

        public static void Main()

        {

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

            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;

            }

        }

        public static string GetNetCoreVersion()

        {

            //https://techblog.dorogin.com/how-to-detect-net-core-version-in-runtime-ecd65ad695be

            //

            var assembly = typeof(System.Runtime.GCSettings).GetTypeInfo().Assembly;

            var assemblyPath = assembly.CodeBase.Split(new[] { '/', '\\' }, StringSplitOptions.RemoveEmptyEntries);

            int netCoreAppIndex = Array.IndexOf(assemblyPath, "Microsoft.NETCore.App");

            if (netCoreAppIndex > 0 && netCoreAppIndex < assemblyPath.Length - 2)

                return assemblyPath[netCoreAppIndex + 1];

            return null;

        }

    }

​