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 System.Reflection;

using System.Runtime.Serialization;

​

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using Newtonsoft.Json.Converters;

using Newtonsoft.Json.Serialization;    

​

using Xunit;

​

//https://stackoverflow.com/questions/56670748/asp-net-core-serialized-object-with-a-fileinfo-returns-incomplete-json

​

    public class Thing

    {

        public string Name { get; set; }

        public FileInfo File { get; set; }

    }

​

#nullable enable

​

    public class FileInfoConverter : JsonConverter<FileInfo>

    {

        public override void WriteJson(JsonWriter writer, FileInfo? value, JsonSerializer serializer) =>

            serializer.Serialize(writer, FileInfoDTO.FromFileInfo(value));

​

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

            serializer.Deserialize<FileInfoDTO>(reader)?.ToFileInfo();

    }

​

    public class FileInfoDTO

    {

        // In .NET Framework, FileSystemInfo.GetObjectData() serialized two properties, so our DTO must have the same properties:

        // https://referencesource.microsoft.com/#mscorlib/system/io/filesysteminfo.cs,340

        //  info.AddValue("OriginalPath", OriginalPath, typeof(String));

        //  info.AddValue("FullPath", FullPath, typeof(String));

        public string OriginalPath { get; set; } = "";

        public string FullPath { get; set; } = "";

        public FileInfoDTO() { }

        public FileInfoDTO(FileInfo info)

        {

            ArgumentNullException.ThrowIfNull(info);

            OriginalPath = info.ToString();

            FullPath = info.FullName;

        }

        // Note that the FileInfo created will present the attrib utes of a file with the specified name on the receiving system, not the sending system

        public FileInfo ToFileInfo() => new FileInfo(OriginalPath); // TODO; decide whether to pass in the Original Path or the Full Path

        public static FileInfoDTO? FromFileInfo(FileInfo? fileInfo) => fileInfo == null ? null : new FileInfoDTO(fileInfo);

    }

​

    class TestClass

    {

        public static void Test()

        {

            var fileName = "Question56670748.txt";

            File.WriteAllText(fileName, "");

            try

            {

                var settings = new JsonSerializerSettings

                {

                    Converters = { new FileInfoConverter() },

                };

​

                var json2 = Test(fileName, settings);

​

            }

            finally

            {

                try

                {

                    File.Delete(fileName);

                }

                catch (Exception)

                {

                }

            }

        }

​

        private static string Test(string fileName, JsonSerializerSettings settings)

        {

            var root = new Thing

            {

                Name = "First thing",

                File = new FileInfo(fileName)

            };

​

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

            Console.WriteLine(json);

​

            var root2 = JsonConvert.DeserializeAnonymousType(json, root, settings);

            var json2 = JsonConvert.SerializeObject(root2, Formatting.Indented, settings);

​

            Console.WriteLine(json2);

​

            Assert.Equal(true, json == json2 && root.File.Name == root2.File.Name);

​

            return json;

        }

    }

​

    public class Program

    {

        public static void Main()

        {

            Console.WriteLine("Environment version: " + Environment.Version);

            Console.WriteLine("{0} version: {1}", typeof(JsonSerializer).Namespace, typeof(JsonSerializer).Assembly.FullName);

            Console.WriteLine();

​

            try

            {

                TestClass.Test();

            }

            catch (Exception ex)

            {

                Console.WriteLine("Failed with unhandled exception: ");

                Console.WriteLine(ex);

                throw;

            }

        }

    }

​