using System;

using System.Linq;

using System.Reflection;

using Newtonsoft.Json;

using Newtonsoft.Json.Converters;

using Newtonsoft.Json.Serialization;

public class Program

{

    public static void Main()

    {

        JsonSerializerSettings settings = new JsonSerializerSettings();

        settings.ContractResolver = new ConditionalDateTimeResolver();

​

        var bank = new Bank()

        {

            Name = "Test bank",

            ConvertThis = new DateTime(2020, 8, 18, 15, 7, 1),

            DontConvertThis = new DateTime(2020, 8, 18, 15, 7, 1)

        };

​

        string json = JsonConvert.SerializeObject(bank, settings);

        Console.WriteLine(json);

    }

}

​

public class Bank

{

    public string Name { get; set; }

    public DateTime ConvertThis { get; set; }

    [TimeZoneIgnore]

    public DateTime DontConvertThis { get; set; }

}

​

public class ConditionalDateTimeResolver : DefaultContractResolver

{

    static readonly JsonConverter DateTimeConverter = new JsonDateTimeConverter();

​

    protected override JsonProperty CreateProperty(MemberInfo member, MemberSerialization memberSerialization)

    {

        JsonProperty prop = base.CreateProperty(member, memberSerialization);

        if (DateTimeConverter.CanConvert(prop.PropertyType) && 

            !prop.AttributeProvider.GetAttributes(typeof(TimeZoneIgnore), true).Any())

        {

            prop.Converter = DateTimeConverter;

        }

        return prop;

    }

}

​

public class JsonDateTimeConverter : DateTimeConverterBase

{

    public override bool CanConvert(Type objectType)

    {

        // I want to return false for object properties which have attribute "TimeZoneIgnore"

        return objectType == typeof(DateTime) || objectType == typeof(DateTime?);

    }

​

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

    {

        throw new NotImplementedException();

    }

​

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

    {

        // convert datetime to timezone

        DateTime? dateTime = (value as DateTime?).ConvertToTimeZone("CEST");

​

        writer.WriteValue(dateTime);

        writer.Flush();

    }

}

​

[AttributeUsage(AttributeTargets.Property)]

public class TimeZoneIgnore : Attribute { }

​

public static class DateExtensions

{

    public static DateTime? ConvertToTimeZone(this DateTime? date, string timeZoneId)

    {

        if (date.HasValue)

        {

            if (timeZoneId == "CEST") timeZoneId = "Europe/Amsterdam";

            return TimeZoneInfo.ConvertTimeBySystemTimeZoneId(date.Value, timeZoneId);

        }

        return null;

    }

}

​