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.Collections.ObjectModel;

​

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using Newtonsoft.Json.Converters;

using Newtonsoft.Json.Serialization;    

​

// https://stackoverflow.com/questions/47317792/handling-json-response-which-sometimes-doesnt-have-array#47317792

​

    public class TolerantCollectionConverter : JsonConverter

    {

        public override bool CanConvert(Type objectType)

        {

            if (objectType.IsPrimitive || objectType == typeof(string) || objectType.IsArray)

                return false;

            return objectType.GetCollectionItemTypes().Count() == 1;

        }

​

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

        {

            if (reader.TokenType == JsonToken.Null)

            {

                return null;

            }

            else if (reader.TokenType == JsonToken.StartArray)

            {

                existingValue = existingValue ?? serializer.ContractResolver.ResolveContract(objectType).DefaultCreator();

                serializer.Populate(reader, existingValue);

                return existingValue;

            }

            else

            {

                reader.Skip();

                return existingValue;

            }

        }

​

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

​

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

        {

            throw new NotImplementedException();

        }

    }

​

    public static class TypeExtensions

    {

        /// <summary>

        /// Return all interfaces implemented by the incoming type as well as the type itself if it is an interface.

        /// </summary>

        /// <param name="type"></param>

        /// <returns></returns>

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

        {

            if (type == null)

                throw new ArgumentNullException();

            if (type.IsInterface)

                return new[] { type }.Concat(type.GetInterfaces());

            else

                return type.GetInterfaces();

        }

​

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

        {

            foreach (Type intType in type.GetInterfacesAndSelf())

            {

                if (intType.IsGenericType

                    && intType.GetGenericTypeDefinition() == typeof(ICollection<>))

                {

                    yield return intType.GetGenericArguments()[0];

                }

            }

        }

    }

​

    public class Field

    {

        public string FIELD_NAME { get; set; }

        public string VALUE { get; set; }

        public int FIELD_ID { get; set; }

​

        // Verify the converter works for general collections and not just List<T>.

        public ObservableCollection<Option> OPTIONS { get; set; }

    }

​

    public class Option

    {

        public string VALUE { get; set; }

        public int DISPLAY_ORDER { get; set; }

        public string DISPLAY { get; set; }

    }

​

    class TestClass

    {

​

        public static void Test()

        {

            foreach (var stringTest in GetJson())

            {

                var settings = new JsonSerializerSettings

                {

                    Converters = { new TolerantCollectionConverter() },

                };

                var obj = JsonConvert.DeserializeObject<Field>(stringTest, settings);

                var newJson = JsonConvert.SerializeObject(obj, Formatting.Indented, settings);

                Console.WriteLine("\nDeserialized and re-serialized {0}", obj);

                Console.WriteLine(newJson);

            }

​

            Console.WriteLine("\nDone.");

        }

​

        static string[] GetJson()

        {

            var json = new[]

            {

                @"{

    ""FIELD_NAME"": ""Survey"",

    ""VALUE"": """",

    ""FIELD_ID"": 1234,

    ""OPTIONS"":[

        { ""VALUE"": ""GENERAL"", ""DISPLAY_ORDER"": 1, ""DISPLAY"": ""GENERAL"" },

        { ""VALUE"": ""HPEFS"",   ""DISPLAY_ORDER"": 3, ""DISPLAY"": ""HPEFS"" },

        { ""VALUE"": ""NONE"",    ""DISPLAY_ORDER"": 3, ""DISPLAY"": ""NONE"" }]

}",

                @"{

    ""FIELD_NAME"": ""Survey"",

    ""VALUE"": """",

    ""FIELD_ID"": 1234,

    ""OPTIONS"":{}

}"            };

​

            return 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();

​

            try

            {

                TestClass.Test();

            }

            catch (Exception ex)

            {

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

                Console.WriteLine(ex);

                throw;

            }

        }

    }

​

    public class AssertionFailedException : System.Exception

    {

        public AssertionFailedException() : base() { }

​

        public AssertionFailedException(string s) : base(s) { }

    }

​

    public static class Assert

    {

        public static void IsTrue(bool value)

        {

            IsTrue(value, "failed");

        }

​

        public static void IsTrue(bool value, string message)

        {

            if (value == false)

                throw new AssertionFailedException(message ?? "failed");

        }

    }

​