using System;

using System.Collections.Generic;

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

public class Program

{

    public static void Main()

    {

        string newerTakeoffJson = @"

        {

          ""$type"": ""TakeoffEvent, MyAssembly"",

          ""TimeOfTakeoff"": ""2021-04-11T15:00:00.000Z"",

          ""Airport"": {

            ""Name"": ""KLAX"",

            ""Runway"": ""25L""

          }

        }";

        DeserializeAndDump(newerTakeoffJson, "newer JSON format - Takeoff");

​

        string newerLandingJson = @"

        {

          ""$type"": ""LandingEvent, MyAssembly"",

          ""TimeOfLanding"": ""2021-04-11T15:30:00.000Z"",

          ""Airport"": {

            ""Name"": ""KLAX"",

            ""Runway"": ""25R""

          }

        }";

        DeserializeAndDump(newerLandingJson, "newer JSON format - Landing");

​

        string legacyTakeoffJson = @"

        {

          ""$type"": ""TakeoffEvent, MyAssembly"",

          ""TimeOfTakeoff"": ""2021-04-12T16:05:00.000Z"",

          ""AirportName"": ""KLAX"",

          ""AirportRunway"": ""25L""

        }";

        DeserializeAndDump(legacyTakeoffJson, "legacy JSON format - Takeoff");

​

​

        string legacyLandingJson = @"

        {

          ""$type"": ""LandingEvent, MyAssembly"",

          ""TimeOfLanding"": ""2021-04-12T16:35:00.000Z"",

          ""AirportName"": ""KLAX"",

          ""AirportRunway"": ""25R""

        }";

        DeserializeAndDump(legacyLandingJson, "legacy JSON format - Landing");

    }

    static void DeserializeAndDump(string json, string message)

    {

        // in .NET Fiddle the assembly name is random, so we have to manually replace it in the JSON sample. 

        // You should not need to do this step in your own code.

        json = json.Replace("MyAssembly", typeof(BaseEvent).Assembly.GetName().Name);

​

        Console.WriteLine("---- " + message + " ----");

        Console.WriteLine(json);

        Console.WriteLine();

​

        var settings = new JsonSerializerSettings

        {

            TypeNameHandling = TypeNameHandling.Objects,

            Converters = new List<JsonConverter> { new EventConverter() },

        };

​

        var baseEvent = JsonConvert.DeserializeObject<BaseEvent>(json, settings);

        if (baseEvent is TakeoffEvent takeoff)

        {

            Console.WriteLine("Time of Takeoff: " + takeoff.TimeOfTakeoff);

        }

        else if (baseEvent is LandingEvent landing)

        {

            Console.WriteLine("Time of Landing: " + landing.TimeOfLanding);

        }

        Console.WriteLine("Airport/Runway: " + baseEvent.Airport.Name + " " + baseEvent.Airport.Runway);

        Console.WriteLine();

    }

}

​

class Airport

{

    public string Name { get; set; }

    public string Runway { get; set; }

}

​

class BaseEvent

{

    public Airport Airport { get; set; }

}

​

class TakeoffEvent : BaseEvent

{

    public DateTime TimeOfTakeoff { get; set; }

}

​

class LandingEvent : BaseEvent

{

    public DateTime TimeOfLanding { get; set; }

}

​

class EventConverter : JsonConverter

{

    public override bool CanConvert(Type objectType)

    {

        return typeof(BaseEvent).IsAssignableFrom(objectType);

    }

​

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

    {

        JObject obj = JObject.Load(reader);

​

        string type = (string)obj["$type"];

        BaseEvent baseEvent;

        if (type.Contains(nameof(TakeoffEvent)))

        {

            baseEvent = new TakeoffEvent();

        }

        else

        {

            baseEvent = new LandingEvent();

        }

        serializer.Populate(obj.CreateReader(), baseEvent);

​

        if (baseEvent.Airport == null)

        {

            baseEvent.Airport = new Airport

            {

                Name = (string)obj["AirportName"],

                Runway = (string)obj["AirportRunway"]

            };

        }

        return baseEvent;

    }

​

    public override bool CanWrite => false;

​

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

    {

        throw new NotImplementedException();

    }

}

​