From JavaScriptSerializer to Newtonsoft.Json

Hi everone,

For a client i'm updating a Exact Online API. In this API they use the old ASP framework. Now i get a lot of errors in my code and one of them is a error at JavaScriptSerializer. This isn't supported in ASP.NET core anymore. Now i read on the internet that the best replacement for this is Newtonsoft.Json.

This is the old code:

public static string GetJsonObject(string response)
{
	var serializer = new JavaScriptSerializer();
	serializer.RegisterConverters(new JavaScriptConverter[] { new JssDateTimeConverter() });
	var oldCulture = Thread.CurrentThread.CurrentCulture;
	Thread.CurrentThread.CurrentCulture = CultureInfo.InvariantCulture;

	string output;
	try
	{
		var dict = (Dictionary<string, object>)serializer.Deserialize<object>(response);
		var d = (Dictionary<string, object>)dict["d"];
		output = GetJsonFromDictionary(d);
	}
	finally
	{
			Thread.CurrentThread.CurrentCulture = oldCulture;
	}
	return output;
}

This is what i'm trying to do with Newtonsoft.Json:

public static string GetJsonObject(string response)
{

    var serializer = new JsonSerializer();
    serializer.Converters.Add(new JsonConverter { new JssDateTimeConverter() });

    var oldCulture = CultureInfo.CurrentCulture;
    CultureInfo.CurrentCulture = CultureInfo.InvariantCulture;

    //var serializer = new JavaScriptSerializer();
    //serializer.RegisterConverters(new JssDateTimeConverter});

    string output;
	try
	{
        var converter = new ExpandoObjectConverter();
        var dict = (Dictionary<string, object>)serializer.Deserialize<object>(response); <- HERE IS THE ERROR

		var d = (Dictionary<string, object>)dict["d"];
		output = GetJsonFromDictionary(d);
	}
	finally
	{
        CultureInfo.CurrentCulture = oldCulture;
	}
	return output;
}

The only problem is that i get the following error in the try catch:

Cannot convert from 'string' to 'Newtonsoft.Json.JsonReader'

Does someone know how to convert the code to Newtonsoft.Json? For the people that want to know what's in the JssDateTimeConverter class:

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using Microsoft.AspNetCore.Mvc.Formatters.Json;
using Microsoft.AspNetCore.JsonPatch;
using Newtonsoft.Json;
using Newtonsoft.Json.Converters;

namespace Site.Models.Exact.Helpers
{
    /// <summary>
    /// Custom JavaScriptConverter for parsing datetime value correctly
    /// </summary>
    public class JssDateTimeConverter : StringEnumConverter // : JavaScriptConverter
    {
		public IEnumerable<Type> SupportedTypes  //override
        {
			get
			{
				return new[] { typeof(Object) };
			}
		}

		public object Deserialize(IDictionary<string, object> dictionary, Type type, JsonSerializer serializer)
		{
			var keys = new List<string>(dictionary.Keys);

			foreach (string key in keys)
			{
				object entity = dictionary[key];

				// Check if content is a dictionary > send to this method recursively
				if (entity != null && entity.GetType() == typeof(Dictionary<string, object>))
				{
					var value = (Dictionary<string, object>)entity;
					Deserialize(value, type, serializer);
				}
				else
				{
					var value = entity;
					if (value != null)
					{
						// Set EPOCH datetime
						Type valueType = value.GetType();
						if (valueType == typeof(DateTime))
						{
							var date = (DateTime)entity;
							TimeSpan t = (date - new DateTime(1970, 1, 1));
							double timestamp = t.TotalMilliseconds;
							dictionary[key] = string.Format("/Date({0})/", timestamp);
						}

						// For collection within this collection > send to this method recursively
						if (valueType == typeof(ArrayList))
						{
							IEnumerable<object> dictionaries = ((ArrayList)value).ToArray().Where(x => x.GetType() == typeof(Dictionary<string, object>));

							foreach (var dict in dictionaries)
							{
								Deserialize((Dictionary<string, object>)dict, type, serializer);
							}
						}
					}
				}
			}
			return dictionary;
		}

		public IDictionary<string, object> Serialize(object obj, JsonSerializer serializer)
		{
			return null;
		}
	}
}

thanks in advance!