using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Text;

​

using System.Text.Json;

using System.Text.Json.Serialization;

using System.Text.Json.Serialization.Metadata;

using System.Text.Json.Nodes;

​

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

​

//https://stackoverflow.com/questions/77879422/system-text-json-dictionary-deserialisation-as-constructor-parameter-with-refere

​

    public class MyClass : IJsonOnDeserialized

    {

        public Dictionary<string, int> MyDictionary { get; set; }

​

        public MyClass() : this(new()) { }

​

        public MyClass(Dictionary<string, int> MyDictionary)

        {

            this.MyDictionary= MyDictionary;

            DoSetup();

        }       

​

        private void DoSetup()

        {

            //...doing some other setup stuff

            // Since this is called after deserialization you can use the populated dictionary in your setup, e.g. like so:

            InitialDictionaryCount = MyDictionary.Count;

        }

​

        void IJsonOnDeserialized.OnDeserialized() => DoSetup();

        [JsonIgnore]

        public int InitialDictionaryCount { get; private set; }

    }

​

    public class Root

    {

        [JsonPropertyOrder(0)]

        public MyClass MyClass { get; set; }

        [JsonPropertyOrder(1)]

        public  Dictionary<string, int> MyClassDictionary { 

            get => MyClass?.MyDictionary; 

            set {  

                if (value != MyClass?.MyDictionary)

                    throw new InvalidOperationException();

            } 

        }

    }

​

    class TestClass

    {

        public static void Test()

        {

            var root = new Root

            {

                MyClass = new()

                {

                    MyDictionary = 

                    {

                        ["aaaa"] = 5661,

                        ["bbbbb"] = 5661,

                    },

                },

            };

            var options = new JsonSerializerOptions

            {

                ReferenceHandler = ReferenceHandler.Preserve,

                WriteIndented = true,

            };

            var json = JsonSerializer.Serialize(root, options);

            Console.WriteLine(json);

            var root2 = JsonSerializer.Deserialize<Root>(json, options);

            Assert.That(root2?.MyClass.MyDictionary == root2.MyClassDictionary);

            Assert.That(root2?.MyClass?.InitialDictionaryCount == 2);

        }

    }

​

    public class Program

    {

        public static void Main()

        {

            Console.WriteLine("Environment version: {0} ({1}), {2}", System.Runtime.InteropServices.RuntimeInformation.FrameworkDescription , Environment.Version, Environment.OSVersion);

            Console.WriteLine("System.Text.Json version: " + typeof(JsonSerializer).Assembly.FullName);

            Console.WriteLine();

​

            try

            {

                TestClass.Test();

            }

            catch (Exception ex)

            {

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

                Console.WriteLine(ex);

                throw;

            }

        }

    }

​