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 Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using Newtonsoft.Json.Converters;

using Newtonsoft.Json.Serialization;    

​

    // https://stackoverflow.com/questions/46549680/json-net-add-property-to-every-class-containing-of-a-certain-type

    public class AddDateTypeFlagContractResolver : DefaultContractResolver

    {

        protected override IList<JsonProperty> CreateProperties(Type type, MemberSerialization memberSerialization)

        {

            var properties = base.CreateProperties(type, memberSerialization);

            for (int i = 0, n = properties.Count; i < n; i++)

            {

                var prop = properties[i];

                if (prop.PropertyType == typeof(DateTime) || prop.PropertyType == typeof(DateTime?))

                {

                    var name = string.Format("{0}$$type", prop.PropertyName);

                    var newProp = new JsonProperty

                    {

                        DeclaringType = type,

                        PropertyName = name,

                        UnderlyingName = name,

                        PropertyType = typeof(string),

                        ValueProvider = new FixedValueProvider("DateTime"), // Replace with yout desired string value.

                        AttributeProvider = NoAttributeProvider.Instance,

                        Readable = true,

                        Writable = false,

                        // Ensure PreserveReferencesHandling and TypeNameHandling do not apply to the synthetic property.

                        ItemIsReference = false, 

                        TypeNameHandling = TypeNameHandling.None,

                    };

                    properties.Add(newProp);

                }

            }

​

            return properties;

        }

    }

​

    public class FixedValueProvider : IValueProvider

    {

        readonly object value;

​

        public FixedValueProvider(object value)

        {

            this.value = value;

        }

​

        #region IValueProvider Members

​

        public object GetValue(object target) { return value; }

​

        public void SetValue(object target, object value)

        {

            throw new NotImplementedException("SetValue not implemented for fixed properties; set JsonProperty.Writable = false.");

        }

​

        #endregion

    }

​

    class NoAttributeProvider : IAttributeProvider

    {

        static NoAttributeProvider() { instance = new NoAttributeProvider(); }

​

        static readonly NoAttributeProvider instance;

​

        public static NoAttributeProvider Instance { get { return instance; } }

​

        public IList<Attribute> GetAttributes(Type attributeType, bool inherit) { return new Attribute[0]; }

​

        public IList<Attribute> GetAttributes(bool inherit) { return new Attribute[0]; }

    }

​

    public class AddDateFromDateTimeContractResolver : DefaultContractResolver

    {

        protected override IList<JsonProperty> CreateProperties(Type type, MemberSerialization memberSerialization)

        {

            var properties = base.CreateProperties(type, memberSerialization);

            for (int i = 0, n = properties.Count; i < n; i++)

            {

                var prop = properties[i];

                if (prop.PropertyType == typeof(DateTime) || prop.PropertyType == typeof(DateTime?))

                {

                    var name = string.Format("{0}$$date", prop.PropertyName);

                    var newProp = new JsonProperty

                    {

                        DeclaringType = type,

                        PropertyName = name,

                        UnderlyingName = name,

                        PropertyType = prop.PropertyType,

                        ValueProvider = new DateTimeToDateValueProvider(prop.ValueProvider),

                        AttributeProvider = NoAttributeProvider.Instance,

                        Readable = true,

                        Writable = false,

                        // Ensure PreserveReferencesHandling and TypeNameHandling do not apply to the synthetic property.

                        ItemIsReference = false,

                        TypeNameHandling = TypeNameHandling.None,

                    };

                    properties.Add(newProp);

                }

            }

​

            return properties;

        }

    }

​

    public class DateTimeToDateValueProvider : ValueProviderDecorator

    {

        public DateTimeToDateValueProvider(IValueProvider baseProvider) : base(baseProvider) { }

​

        public override object GetValue(object target)

        {

            var baseValue = base.GetValue(target);

            if (baseValue is DateTime)

            {

                return ((DateTime)baseValue).Date;

            }

            return baseValue;

        }

​

        public override void SetValue(object target, object value)

        {

            throw new NotImplementedException();

        }

    }

​

    public abstract class ValueProviderDecorator : IValueProvider

    {

        readonly IValueProvider baseProvider;

​

        public ValueProviderDecorator(IValueProvider baseProvider)

        {

            if (baseProvider == null)

                throw new ArgumentNullException();

            this.baseProvider = baseProvider;

        }

​

        public virtual object GetValue(object target) { return baseProvider.GetValue(target); }

​

        public virtual void SetValue(object target, object value) { baseProvider.SetValue(target, value); }

    }

​

    public class Example

    {

        public string NotADate { get; set; }

        public DateTime ADate { get; set; }

        public DateTime? AnotherDate { get; set; }

    }

​

    class TestClass

    {

        public static void Test()

        {

            var settings = new JsonSerializerSettings

            {

                ContractResolver = new AddDateTypeFlagContractResolver(),

            };

​

            TestExample(settings);

​

            settings.ContractResolver = new AddDateFromDateTimeContractResolver();

​

            TestExample(settings);

​

            //TestAndValidate();

​

            Console.WriteLine("\nDone.");

        }

​

        static void TestExample(JsonSerializerSettings settings)

        {

            Console.WriteLine("\nTesting {0}", settings.ContractResolver);

​

            var example = new Example

            {

                ADate = DateTime.Parse("2017-04-23T18:25:43.511Z", CultureInfo.InvariantCulture),

                AnotherDate = DateTime.Parse("2017-04-23T18:25:43.511Z", CultureInfo.InvariantCulture),

                NotADate = "a value",

            };

​

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

​

            Console.WriteLine(string.Format("Serialized {0}:", example));

            Console.WriteLine(json);

​

            var example2 = JsonConvert.DeserializeObject<Example>(json);

            var json2 = JsonConvert.SerializeObject(example2, Formatting.Indented, settings);

            Console.WriteLine(json2);

        }

    }

​

    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");

        }

    }

​