using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Data;

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/66238081/deserialize-json-list-thats-inside-a-dictionary

​

// MCVE: https://dotnetfiddle.net/0EqVPe

​

    public class ListItemConverterDecorator : JsonConverter

    {

        readonly JsonConverter itemConverter;

        public ListItemConverterDecorator(Type type) => 

            itemConverter = (JsonConverter)Activator.CreateInstance(type ?? throw new ArgumentNullException());

​

        public override bool CanConvert(Type objectType) =>

            !objectType.IsPrimitive && objectType != typeof(string) && objectType.BaseTypesAndSelf().Any(t => t.IsGenericType && t.GetGenericTypeDefinition() == typeof(List<>));

        public override bool CanRead => itemConverter.CanRead;

        public override bool CanWrite => itemConverter.CanWrite;

        public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)

        {

            var itemType = objectType.BaseTypesAndSelf().Where(t => t.IsGenericType && t.GetGenericTypeDefinition() == typeof(List<>)).Select(t => t.GetGenericArguments()[0]).First();

            if (reader.MoveToContentAndAssert().TokenType == JsonToken.Null)

                return null;

            if (reader.TokenType != JsonToken.StartArray)

                throw new JsonSerializationException(string.Format("Unexpected token {0}, expected {1}", reader.TokenType, JsonToken.StartArray));

            var list = existingValue as IList ?? (IList)serializer.ContractResolver.ResolveContract(objectType).DefaultCreator();

            while (reader.ReadToContentAndAssert().TokenType != JsonToken.EndArray)

                list.Add(itemConverter.ReadJson(reader, itemType, null, serializer));

            return list;

        }

        public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)

        {

            writer.WriteStartArray();

            foreach (var item in (IList)value)

                if (item == null)

                    writer.WriteNull();

                else

                    itemConverter.WriteJson(writer, item, serializer);

            writer.WriteEndArray();

        }

    }

​

    public static partial class JsonExtensions

    {

        public static JsonReader ReadToContentAndAssert(this JsonReader reader) =>

            reader.ReadAndAssert().MoveToContentAndAssert();

​

        public static JsonReader MoveToContentAndAssert(this JsonReader reader)

        {

            if (reader == null)

                throw new ArgumentNullException();

            if (reader.TokenType == JsonToken.None)       // Skip past beginning of stream.

                reader.ReadAndAssert();

            while (reader.TokenType == JsonToken.Comment) // Skip past comments.

                reader.ReadAndAssert();

            return reader;

        }

​

        public static JsonReader ReadAndAssert(this JsonReader reader)

        {

            if (reader == null)

                throw new ArgumentNullException();

            if (!reader.Read())

                throw new JsonReaderException("Unexpected end of JSON stream.");

            return reader;

        }

    }

​

    public static class TypeExtensions

    {

        public static IEnumerable<Type> BaseTypesAndSelf(this Type type)

        {

            while (type != null)

            {

                yield return type;

                type = type.BaseType;

            }

        }

    }

​

    public class Example 

    {

        [JsonConverter(typeof(CustomConverter))]

        public int ExampleInt { get; set; }

        [JsonProperty(ItemConverterType = typeof(CustomConverter))]

        public IntList ExampleList { get; set; }

        // How do I specify the Converter attribute for the int in the following line?

        [JsonProperty(ItemConverterType = typeof(ListItemConverterDecorator), 

                      ItemConverterParameters = new object [] { typeof(CustomConverter) })]

        public Dictionary<string, List<int>> ExampleDictionary { get; set; }

    }

​

    public class IntList : List<int> { }

​

    public class CustomConverter : JsonConverter<int>

    {

        public override void WriteJson(JsonWriter writer, int value, JsonSerializer serializer) =>

            writer.WriteValue(-value);

​

        public override int ReadJson(JsonReader reader, Type objectType, int existingValue, bool hasExistingValue, JsonSerializer serializer)

        {

            if (reader.TokenType == JsonToken.Integer)

                return -Convert.ToInt32(reader.Value);

            throw new JsonSerializationException();

        }       

    }

​

    class TestClass

    {

        public static void Test()

        {

            var example = new Example

            {

                ExampleInt = 10,

                ExampleList = new() { 10, 11, 12 },

                ExampleDictionary = new()

                {

                    { "value1", new() { 10, 11, 12 } },

                    { "value2", new() { 20, 21, 22 } },

                    { "value3", null },

                },

            };

            var json = JsonConvert.SerializeObject(example);

            Console.WriteLine(json);

            Assert.AreEqual(@"{""ExampleInt"":-10,""ExampleList"":[-10,-11,-12],""ExampleDictionary"":{""value1"":[-10,-11,-12],""value2"":[-20,-21,-22],""value3"":null}}", json);

            var example2 = JsonConvert.DeserializeObject<Example>(json);

            Assert.AreEqual(example.ExampleInt, example2.ExampleInt);

            Assert.IsTrue(example.ExampleList.SequenceEqual(example2.ExampleList));

            Assert.IsTrue(example.ExampleDictionary.Values.Where(i => i != null).SelectMany(i => i).SequenceEqual(example2.ExampleDictionary.Values.Where(i => i != null).SelectMany(i => i)));

        }   

    }

​

    public class Program

    {

        public static void Main()

        {

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

            Console.WriteLine("{0} version: {1}", typeof(JsonSerializer).Assembly.GetName().Name,  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.Location.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;

        }

    }

​