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.Reflection;

using System.Collections.ObjectModel;

​

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/37995738/json-net-how-to-make-defaultvaluehandling-only-apply-to-certain-types

​

    public class DefaultValueContractResolver : DefaultContractResolver

    {

        readonly Dictionary<Type, DefaultValueHandling> overrides;

​

        public DefaultValueContractResolver(IEnumerable<KeyValuePair<Type, DefaultValueHandling>> overrides) : base()

        {

            if (overrides == null)

                throw new ArgumentNullException("overrides");

            this.overrides = overrides.ToDictionary(p => p.Key, p => p.Value);

        }

​

        protected override JsonProperty CreateProperty(MemberInfo member, MemberSerialization memberSerialization)

        {

            var property = base.CreateProperty(member, memberSerialization);

            if (property.DefaultValueHandling == null)

            {

                DefaultValueHandling handling;

                if (overrides.TryGetValue(property.PropertyType, out handling))

                    property.DefaultValueHandling = handling;

            }

​

            return property;

        }

    }

​

    public class PartnerLoginOptions

    {

        public string Username { get; set; }

        public string Password { get; set; }

        public string DeviceModel { get; set; }

        public string Version { get; set; }

​

        public bool? IncludeUrls { get; set; }

        public bool? ReturnDeviceType { get; set; }

        public bool? ReturnUpdatePromptVersions { get; set; }

    }

​

    class TestClass

    {

        public static void Test()

        {

            var resolver = new DefaultValueContractResolver(

                new Dictionary<Type, DefaultValueHandling>

                { 

                    { typeof(bool?), DefaultValueHandling.Ignore } 

                })

                {

                    NamingStrategy = new CamelCaseNamingStrategy()

                };

​

            var settings = new JsonSerializerSettings { ContractResolver = resolver };

            Test(settings, typeof(bool?));

​

            var settings2 = new JsonSerializerSettings

            {

                ContractResolver = new DefaultValueContractResolver(new Dictionary<Type, DefaultValueHandling> { { typeof(string), DefaultValueHandling.Ignore } })

                {

                    NamingStrategy = new CamelCaseNamingStrategy()

                },

            };

​

            Test(settings2, typeof(string));

        }

        private static void Test(JsonSerializerSettings settings, Type typeToExclude)

        {

            Console.WriteLine("Testing exclusion of default values of type {0}:", typeToExclude);

​

            var options = new PartnerLoginOptions

            {

                Username = null,

                Password = "123",

                IncludeUrls = null,

                ReturnDeviceType = true

            };

​

            var json = JsonConvert.SerializeObject(options, Formatting.Indented, settings);

            Console.WriteLine(json);

​

            IEqualityComparer comparer = EqualityComparer<object>.Default;

            foreach (var property in options.GetType().GetProperties().Where(p => p.PropertyType == typeToExclude))

            {

                var value = property.GetValue(options);

                var defaultValue = GetDefault(property.PropertyType);

                var isDefault = comparer.Equals(value, defaultValue);

                var contains = json.IndexOf("\"" + property.Name + "\"", StringComparison.OrdinalIgnoreCase) >= 0;

                Assert.IsTrue(isDefault != contains);

            }

        }

​

        public static object GetDefault(Type type)

        {

            if (type.IsValueType)

            {

                return Activator.CreateInstance(type);

            }

            return null;

        }

    }

​

    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.CodeBase.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;

        }

    }

​