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.Collections.ObjectModel;

​

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using Newtonsoft.Json.Converters;

using Newtonsoft.Json.Serialization;    

​

using NUnit.Framework; // Throws NUnit.Framework.AssertionException

​

//https://stackoverflow.com/questions/66581597/json-property-name-as-whole-json-path-to-the-property

​

    public class Person

    {

        public string FirstName { get; set; }

        public string LastName { get; set; }

        public Address Address { get; set; }

    }

​

    public class Address

    {

        public string Street { get; set; }

        public string StreetNumber { get; set; }

    }

​

    public class NameRemappingJsonWriter : JsonTextWriter

    {

        readonly Action<string> jsonWriterWritePropertyName;

        readonly Func<string, int, string, string> map;

​

        public NameRemappingJsonWriter(TextWriter textWriter, Func<string, int, string, string> map) : base(textWriter)

        {

            this.map = map ?? throw new ArgumentNullException(nameof(map));

            //Method to call a base-of-base-class method taken from this answer https://stackoverflow.com/a/32562464

            //By https://stackoverflow.com/users/5311735/evk

            //To https://stackoverflow.com/questions/2323401/how-to-call-base-base-method

            var ptr = typeof(JsonWriter).GetMethod("WritePropertyName", new[] { typeof(string) }).MethodHandle.GetFunctionPointer();

            jsonWriterWritePropertyName = (Action<string>)Activator.CreateInstance(typeof(Action<string>), this, ptr);

        }

​

        public override void WritePropertyName(string name) => WritePropertyName(name, true);

​

        public override void WritePropertyName(string name, bool escape)

        {

            jsonWriterWritePropertyName(name);

            WriteRaw(JsonConvert.ToString(map(name, Top, Path)));

            WriteRaw(":");

        }       

    }

​

    class TestClass

    {

        public static void Test()

        {

            var person = new Person

            {

                FirstName = "Homer",

                LastName = "Simpson",

                Address = new () 

                {

                    Street = "Evergreen Terrace",

                    StreetNumber = "742",

                },

            };

​

            var settings = new JsonSerializerSettings

            {

                ContractResolver = new CamelCasePropertyNamesContractResolver(),

            };

            Func<string, int, string, string> map = (name, depth, parentPath) => "person." + parentPath;

            using var textWriter = new StringWriter();

            using (var jsonWriter = new NameRemappingJsonWriter(textWriter, map) { Formatting = Formatting.Indented })

            {

                JsonSerializer.CreateDefault(settings).Serialize(jsonWriter, person);

            }

            var json = textWriter.ToString();

            Console.WriteLine(json);

            Assert.IsTrue(JToken.DeepEquals(JToken.Parse(GetRequiredJson()), JToken.Parse(json)));

        }   

        static string GetRequiredJson() => @"{

   ""person.firstName"":""Homer"",

   ""person.lastName"":""Simpson"",

   ""person.address"":{

      ""person.address.street"":""Evergreen Terrace"",

      ""person.address.streetNumber"":""742""

   }

}"; }

​

    public class Program

    {

        public static void Main()

        {

            Console.WriteLine("Environment version: {0} ({1})", System.Runtime.InteropServices.RuntimeInformation.FrameworkDescription , GetNetCoreVersion());

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

            Console.WriteLine();

​

            try

            {

                TestClass.Test();

            }

            catch (Exception ex)

            {

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

                Console.WriteLine(ex);

                throw;

            }

        }

        public static string GetNetCoreVersion()

        {

            //https://techblog.dorogin.com/how-to-detect-net-core-version-in-runtime-ecd65ad695be

            //

            var assembly = typeof(System.Runtime.GCSettings).GetTypeInfo().Assembly;

            var assemblyPath = assembly.Location.Split(new[] { '/', '\\' }, StringSplitOptions.RemoveEmptyEntries);

            int netCoreAppIndex = Array.IndexOf(assemblyPath, "Microsoft.NETCore.App");

            if (netCoreAppIndex > 0 && netCoreAppIndex < assemblyPath.Length - 2)

                return assemblyPath[netCoreAppIndex + 1];

            return null;

        }

    }

​

#if false

    public class PropertyPathNameJsonTextWriter : JsonTextWriter

    {

        Action<string> jsonWriterWritePropertyName;

​

        public PropertyPathNameJsonTextWriter(TextWriter textWriter)

            : base(textWriter)

        {

            //Method to call a base-of-base-class method taken from this answer https://stackoverflow.com/a/32562464

            //By https://stackoverflow.com/users/5311735/evk

            //To https://stackoverflow.com/questions/2323401/how-to-call-base-base-method

            var ptr = typeof(JsonWriter).GetMethod("WritePropertyName", new[] { typeof(string) }).MethodHandle.GetFunctionPointer();

            jsonWriterWritePropertyName = (Action<string>)Activator.CreateInstance(typeof(Action<string>), this, ptr);

        }

​

        public override void WritePropertyName(string name)

        {

            WritePropertyName(name, true);

        }

​

        public override void WritePropertyName(string name, bool escape)

        {

            jsonWriterWritePropertyName(name);

            WriteRaw(escape ? JsonConvert.ToString(Path) : Path);

            WriteRaw(":");

        }

    }

#endif

​