using System;

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using Newtonsoft.Json.Serialization;

​

var settings = new JsonSerializerSettings

{

    ContractResolver = new DefaultContractResolver

    {

        NamingStrategy = new SnakeCaseNamingStrategy()

    }

};

​

var serialized = JsonConvert.SerializeObject(

    new Container

    {

        SomeProperty = new PropertyImplementationA

        {

            PropertyA = "some string value"

        }

    }, settings);

​

Console.WriteLine("Serialized correctly:");

Console.WriteLine(serialized);

​

// Doesn't use the converter

var deserialized = JsonConvert.DeserializeObject<Container>(serialized);

​

Console.WriteLine();

Console.WriteLine("Converter not used when deserializing");

Console.WriteLine(JsonConvert.SerializeObject(deserialized, settings));

​

​

class PropertyImplementationA : PropertyBase

{

    override public string Type => nameof(PropertyImplementationA);

​

    public string PropertyA { get; set; }

}

​

class PropertyImplementationB : PropertyBase

{

    override public string Type => nameof(PropertyImplementationB);

​

    public int PropertyB { get; set; }

}

​

abstract class PropertyBase

{

    public abstract string Type { get; }

}

​

class PropertyConverter : JsonConverter<PropertyBase>

{

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

    {

        throw new NotImplementedException();

    }

​

    override public bool CanWrite => false;

​

    override public PropertyBase? ReadJson(JsonReader reader, Type objectType, PropertyBase? existingValue, bool hasExistingValue, JsonSerializer serializer)

    {

        Console.WriteLine();

        Console.WriteLine("JsonConverter used");

        if (reader.TokenType == JsonToken.Null) return null;

​

        var jObject = JObject.Load(reader);

        var target = Create(jObject);

​

        if (target != null) serializer.Populate(jObject.CreateReader(), target);

​

        return target;

    }

​

    private PropertyBase Create(JObject jObject)

    {

        if (jObject == null)

            throw new ArgumentNullException(nameof(jObject));

​

        var sourceType = jObject.SelectToken("type")?.Value<string>();

​

        return sourceType switch

        {

            nameof(PropertyImplementationA) => new PropertyImplementationA(),

            nameof(PropertyImplementationB) => new PropertyImplementationB(),

            _ => null

        };

    }

}

​

class Container

{

    [JsonConverter(typeof(PropertyConverter))]

    public PropertyBase SomeProperty { get; set; }

}