open System

open System.Collections

open System.Collections.Generic

open System.Linq

open System.Text

open System.Runtime.Serialization.Formatters

open System.IO

open System.Data

open System.ComponentModel.DataAnnotations

open System.Globalization

​

open Newtonsoft.Json

open Newtonsoft.Json.Linq

open Newtonsoft.Json.Converters

open Newtonsoft.Json.Serialization

​

// https://stackoverflow.com/questions/56613259/newtonsoft-deserializing-json-incorrectly

​

type TradeDate(date : DateTime) = 

    member this.Year = date.Year

    member this.Month = date.Month

    member this.DayOfMonth = date.Day

​

[<AllowNullLiteral>] type private TradeDateDTO(year : int, month : int, dayOfMonth : int) =

    member this.Year = year

    member this.Month = month

    member this.DayOfMonth = dayOfMonth

​

type TradeDateConverter () =

    inherit JsonConverter()

    override this.CanConvert(t) = (t = typedefof<TradeDate>)

​

    override this.ReadJson(reader, t, existingValue, serializer) = 

        let dto = serializer.Deserialize<TradeDateDTO>(reader)

        match dto with

        | null -> raise (new JsonSerializationException("null TradeDate"))

        | _ -> new TradeDate(new DateTime(dto.Year, dto.Month, dto.DayOfMonth)) :> Object

​

    override this.CanWrite = false

​

    override this.WriteJson(writer, value, serializer) = 

        raise (new NotImplementedException());

​

let converter = new TradeDateConverter()

let t1 = new TradeDate(new DateTime(1997, 12, 25))

let json1 = JsonConvert.SerializeObject(t1, converter)

let t2 = JsonConvert.DeserializeObject<TradeDate>(json1, converter)

let json2 = JsonConvert.SerializeObject(t2, converter)

​

printfn "\nResult of serializing a %s to JSON:\n%s" (t1.GetType().Name) json1

​

printfn "\nResult after round-trip :\n%s" json2

​

if json1 = json2 then printfn "Results are identical."

else printfn "Results differ!"

​