using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Diagnostics;

using System.IO;

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.Text.RegularExpressions;

using System.Runtime.Serialization.Formatters;

using System.ComponentModel.DataAnnotations;

​

​

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using Newtonsoft.Json.Converters;

using Newtonsoft.Json.Serialization;

​

​

    // https://stackoverflow.com/questions/45045546/json-net-serializes-empty-json

    //Plant.cs

    public interface ICell

    {

        int Id { get; }

    }

    public interface IEukaryote

    {

        System.Collections.Generic.IEnumerable<ICell> Cells { get; }

        string GenericName { get; }

    }

    public sealed partial class PlantCell

        : ICell

    {

        public int Id { get { return 12324; } }

    }

​

    public sealed partial class Plant : IEukaryote

    {

        public System.Collections.Generic.IEnumerable<ICell> Cells { get { return (_valuesDict["Cells"] as System.Collections.IEnumerable).Cast<ICell>(); } }

        public string GenericName { get { return _valuesDict["GenericName"] as string; } }

        public string FieldIWantSerialized;

        public int SomethingIDoNotWantSerialized { get { return 99999; } }

​

        private readonly System.Collections.Generic.IDictionary<string, object> _valuesDict;

        public Plant()

        {

            _valuesDict = new System.Collections.Generic.Dictionary<string, object>();

            var cells = new System.Collections.Generic.List<PlantCell>();

            cells.Add(new PlantCell());

            _valuesDict["Cells"] = cells;

            _valuesDict["GenericName"] = "HousePlant";

            this.FieldIWantSerialized = "FieldIWantSerialized Value";

        }

​

        public override string ToString()

        {

            return Newtonsoft.Json.JsonConvert.SerializeObject(this,

                new Newtonsoft.Json.JsonSerializerSettings()

                {

                    ContractResolver = new Newtonsoft.Json.Serialization.CamelCasePropertyNamesContractResolver()

                }

            );

        }

    }

​

    //Metadata.cs

    [System.ComponentModel.DataAnnotations.MetadataType(typeof(PlantMetadata))]

    public sealed partial class Plant

    {

        [JsonObject(MemberSerialization.OptIn)]

        internal sealed class PlantMetadata

        {

            [JsonProperty]

            public object Cells { get; set; }

​

            [JsonProperty]

            public object GenericName { get; set; }

​

            [JsonProperty]

            public object FieldIWantSerialized;

        }

    }

​

    class TestClass

    {

        public static void Test()

        {

            var plant = new Plant();

​

            var s = plant.ToString();

            Console.WriteLine(s);

            Assert.IsTrue(s.Contains("fieldIWantSerialized"));

            Assert.IsTrue(s.IndexOf("SomethingIDoNotWantSerialized", StringComparison.OrdinalIgnoreCase) == -1);

            Assert.IsTrue(s.Contains("cells"));

            Assert.IsTrue(s.Contains("genericName"));

        }

    }

​

    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();

        }

    }

​

    public class AssertionFailedException : System.Exception

    {

        public AssertionFailedException() : base() { }

​

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

    }

​

    public static class Assert

    {

        public static void IsTrue(bool value)

        {

            if (value == false)

                throw new AssertionFailedException("failed");

        }

    }