using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Diagnostics;

using System.IO;

using System.Threading;

using System.Collections.ObjectModel;

using System.Reflection;

using System.Runtime.Serialization;

using System.Data;

using System.ComponentModel;

using System.Globalization;

using System.Collections.Specialized;

using System.Web.Routing;

using System.Runtime.InteropServices;

using System.Text.RegularExpressions;

using System.Net;

using System.Runtime.Serialization.Formatters;

​

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using Newtonsoft.Json.Converters;

using Newtonsoft.Json.Serialization;

​

    // https://stackoverflow.com/questions/43376404/web-api-jsonconverter-custom-attribute

    public class CustomDateConverter : JsonConverter

    {

        private string[] formats = new string[] { "yyyy-MM-dd", "MM/dd/yy", "MM/dd/yyyy", "dd-MMM-yy" };

​

        public CustomDateConverter(params string[] dateFormats)

        {

            this.formats = dateFormats;

            Console.WriteLine(string.Format("Constructed a {0} with arguments {1}", GetType(), JsonConvert.SerializeObject(dateFormats)));

        }

​

        public override bool CanConvert(Type objectType)

        {

            return objectType == typeof(DateTime);

        }

​

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

        {

            throw new InvalidOperationException();

        }

​

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

        {

            var date = (DateTime)value;

            writer.WriteValue(date.ToString(formats.Last())); // For example, write the value using the last format.

            //writer.WriteValue(date.ToString(formats[0]));   // Or the first format, if you prefer.

        }

    }

​

    public class RootObject

    {

        [JsonConverter(typeof(CustomDateConverter), new object [] { new string [] {  "dd-MMM-yy", "yyyy-MM-dd", "MM/dd/yy", "MM/dd/yyyy" } } )]

        //[JsonConverter(typeof(CustomDateConverter), new object [] { "dd-MMM-yy", "yyyy-MM-dd", "MM/dd/yy", "MM/dd/yyyy" } )]  // Does not work

        public DateTime DateTime { get; set; }

    }

​

    class TestClass

    {

        public static void Test()

        {

            var root = new RootObject { DateTime = DateTime.Now };

            var json = JsonConvert.SerializeObject(root);

            Console.WriteLine(json);

        }

    }

​

    public class Program

    {

        public static void Main()

        {

            Console.WriteLine("Environment version: " + Environment.Version);

            Console.WriteLine("Json.NET version: " + typeof(JsonSerializer).Assembly.FullName);

            Console.WriteLine("");

            TestClass.Test();

        }

    }

​