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 System.Text.Json;

using System.Text.Json.Serialization;

​

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

​

//https://stackoverflow.com/questions/59828937/how-to-exclude-an-enum-property-of-a-model-from-using-the-jsonstringenumconverte

​

    public class OptOutJsonConverterFactory : JsonConverterFactoryDecorator

    {

        readonly HashSet<Type> optOutTypes;

        public OptOutJsonConverterFactory(JsonConverterFactory innerFactory, params Type [] optOutTypes) : base(innerFactory) => this.optOutTypes = optOutTypes.ToHashSet();

​

        public override bool CanConvert(Type typeToConvert) => base.CanConvert(typeToConvert) && !optOutTypes.Contains(typeToConvert);

    }

    public class JsonConverterFactoryDecorator : JsonConverterFactory

    {

        readonly JsonConverterFactory innerFactory;

        public JsonConverterFactoryDecorator(JsonConverterFactory innerFactory)

        {

            if (innerFactory == null)

                throw new ArgumentNullException(nameof(innerFactory));

            this.innerFactory = innerFactory;

        }

​

        public override bool CanConvert(Type typeToConvert) => innerFactory.CanConvert(typeToConvert);

        public override JsonConverter CreateConverter(Type typeToConvert, JsonSerializerOptions options) => innerFactory.CreateConverter(typeToConvert, options);

    }

​

    public enum StringEnum

    {

        Name1, 

        Name2,

        Name3,

    }

​

    public enum SomeEnumNotToSerializeAsAString

    {

        Value1, 

        Value2,

        Value3,

    }

​

    public class Model

    {

        public StringEnum StringEnum { get; set; }

        public SomeEnumNotToSerializeAsAString SomeEnumNotToSerializeAsAString { get; set; }

    }

​

    class TestClass

    {

        public static void Test()

        {

            var options = new JsonSerializerOptions

            {

                IgnoreNullValues = true,

                PropertyNameCaseInsensitive = true,

            };

            options.Converters.Add(new OptOutJsonConverterFactory(new JsonStringEnumConverter(), 

                                                                  // Add here all enum types to serialize as integers:

                                                                  typeof(SomeEnumNotToSerializeAsAString)

                                                                  //, ...

                                                                 ));

            var model = new Model

            {

                StringEnum = StringEnum.Name2,

                SomeEnumNotToSerializeAsAString = SomeEnumNotToSerializeAsAString.Value2

            };

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

            Console.WriteLine(json);

            Assert.IsTrue(!Enum.GetNames(typeof(SomeEnumNotToSerializeAsAString)).Any(n => json.Contains(n)));

            Assert.IsTrue(Enum.GetNames(typeof(StringEnum)).Any(n => json.Contains(n)));

        }   

    }

​

    public class Program

    {

        public static void Main()

        {

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

            Console.WriteLine("System.Text.Json: " + 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;

        }

    }

​