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/61033781/deserialize-a-property-name-that-can-have-different-types

/*

Your JSON is not well-formed.  The second `"propertyNames"` value needs to be delimited by `{` and `}` not `[` and `]`.  But if I fix that then `[JsonConverter(typeof(ListToDictionaryConverter<MyObject>))]` works, see https://dotnetfiddle.net/kHcBaw.  Mark as a duplicate?

*/

​

    public class MyObject

    {

        public string a { get; set; }

        public string b { get; set; }

        public string z { get; set; }

    }

​

    public class Datum

    {

        [JsonConverter(typeof(ListToDictionaryConverter<MyObject>))]

        public List<MyObject> propertyNames { get; set; }

        public string otherProperty { get; set; }

    }

​

    public class RootObject

    {

        public List<Datum> data { get; set; }

    }

​

    public class ListToDictionaryConverter<T> : JsonConverter where T : class

    {

        // From this answer https://stackoverflow.com/a/41559688/3744182

        // To https://stackoverflow.com/questions/41553379/display-json-object-array-in-datagridview

        public override bool CanConvert(Type objectType)

        {

            return typeof(List<T>).IsAssignableFrom(objectType);

        }

​

        public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)

        {

            if (reader.TokenType == JsonToken.Null)

                return null;

            var list = existingValue as List<T> ?? (List<T>)serializer.ContractResolver.ResolveContract(objectType).DefaultCreator();

            if (reader.TokenType == JsonToken.StartArray)

                serializer.Populate(reader, list);

            else if (reader.TokenType == JsonToken.StartObject)

            {

                var dict = serializer.Deserialize<Dictionary<int, T>>(reader);

                foreach (var pair in dict)

                    list.SetOrAddAt(pair.Key, pair.Value, default(T));

            }

            else

            {

                throw new JsonSerializationException(string.Format("Invalid token {0}", reader.TokenType));

            }

            return list;

        }

​

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

        {

            var list = (IList<T>)value;

            writer.WriteStartObject();

            for (int i = 0; i < list.Count; i++)

            {

                // Omit null values.

                if (list[i] == default(T))

                    continue;

                writer.WritePropertyName(((JValue)i).ToString());

                serializer.Serialize(writer, list[i]);

            }

            writer.WriteEndObject();

        }

    }

​

    public static class ListExtensions

    {

        // From this answer https://stackoverflow.com/a/41559688/3744182

        // To https://stackoverflow.com/questions/41553379/display-json-object-array-in-datagridview

        public static void SetOrAddAt<T>(this IList<T> list, int index, T value, T defaultValue = default(T))

        {

            if (list == null)

                throw new ArgumentNullException("list");

            list.EnsureCount(index + 1, defaultValue);

            list[index] = value;

        }

​

        public static void EnsureCount<T>(this IList<T> list, int count, T defaultValue = default(T))

        {

            if (list == null)

                throw new ArgumentNullException("list");

            int oldCount = list.Count;

            if (count > oldCount)

            {

                for (int i = oldCount; i < count; i++)

                    list.Add(defaultValue);

            }

        }

    }

​

    class TestClass

    {

        public static void Test()

        {

            var json = GetJson();

            var root = JsonConvert.DeserializeObject<RootObject>(json);

​

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

            Console.WriteLine("Re-serialized {0}", root);

            Console.WriteLine(json2);

        }   

        static string GetJson()

        {

            var json = @"{

    ""data"": [

        {

            ""propertyNames"":[

                {

                    ""a"":""a1"",

                    ""b"":""b1"",

                    ""z"":""z1""

                },

                {

                    ""a"":""a2"",

                    ""b"":""b2"",

                    ""z"":""z2""

                },

            ],

            ""otherProperty"": ""abc""

        },

        {

            ""propertyNames"":{

                ""1"": {

                    ""a"":""a1"",

                    ""b"":""b1"",

                    ""z"":""z1""

                },

                ""2"": {

                    ""a"":""a2"",

                    ""b"":""b2"",

                    ""z"":""z2""

                },

            },

            ""otherProperty"": ""bce""

        }

    ]

}

";

            return json;

        }

    }

​

    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.CodeBase.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;

        }

    }

​