using System;

using System.ComponentModel;

using System.ComponentModel.DataAnnotations.Schema;

using System.ComponentModel.DataAnnotations;

​

using Microsoft.EntityFrameworkCore;

using Microsoft.EntityFrameworkCore.Storage.ValueConversion;

​

using System.Reflection;

using System.Collections.Generic;

using System.Linq;

using System.Text.Json;

using System.Text.Json.Serialization;

​

namespace EFTest

{

    public class Program

    {

        public static void Main()

        {   

            using (var _context = new TestContext())

            {

                _context.Database.EnsureCreated();

                _context.Models.AddRange(new List<Model>

                                         {

                                             new Model { Type = ItemType.Wall },

                                             new Model { Type = ItemType.Floor },

                                         });

                _context.SaveChanges();

                //var _models =  _context.Models.FromSql(@$"SELECT 1 AS Id, 'i' AS Type

                //                                     UNION SELECT 2 AS Id, 's' AS Type").ToList();

                var _models =  _context.Models.ToList();

                Console.WriteLine(JsonSerializer.Serialize(_models, 

                                                           new JsonSerializerOptions 

                                                           { 

                                                               WriteIndented = true,

                                                                Converters =

                                                                {

                                                                    new JsonStringEnumConverter(JsonNamingPolicy.CamelCase)

                                                                }

                                                           }));

            }

        }

    }

​

    public class TestContext : DbContext

    {

        public TestContext()

        {

​

        }

​

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)

        {

#if USING_SQLITE

            optionsBuilder

                .UseSqlServer(FiddleHelper.GetConnectionStringSqlServer(), o => o

                    .UseQuerySplittingBehavior(QuerySplittingBehavior.SplitQuery))

                ;

#else

            optionsBuilder

                .UseSqlServer(FiddleHelper.GetConnectionStringSqlServer(), o => o

                    .UseQuerySplittingBehavior(QuerySplittingBehavior.SplitQuery))

                ;

#endif

        }

        protected override void OnModelCreating(ModelBuilder modelBuilder)

        {

            var enumDescriptionMappingConverter = new ValueConverter<ItemType, string>(

                v => v.ToDescription(), 

                v => EnumExtensions.GetValueByDescriptionAttribute<ItemType>(v));

                Console.WriteLine("ConvertFromProviderExpression: " +  enumDescriptionMappingConverter.ConvertFromProviderExpression);

                Console.WriteLine("ConvertToProviderExpression: " +  enumDescriptionMappingConverter.ConvertToProviderExpression);

                modelBuilder.Entity<Model>()

                    .Property(e => e.Type)

                    .HasConversion(enumDescriptionMappingConverter);

        }

​

        public DbSet<Model> Models { get; set; }

    }

​

    public static class EnumExtensions

    {

        public static string ToDescription(this Enum value)

        {

            var attribute = value.GetAttribute<DescriptionAttribute>();

            if (attribute == null)

                return value.ToString();

            return attribute.Description;

        }

​

        public static TEnum GetValueByDescriptionAttribute<TEnum>(string value)

            where TEnum : Enum

        {

            var enumDict = Enum.GetValues(typeof(TEnum))

                .Cast<TEnum>()

                .ToDictionary(k => k, v => v.ToDescription());

            return enumDict

                .Single(x => x.Value == value)

                .Key;

        }

​

        private static T GetAttribute<T>(this Enum value)

            where T : Attribute

        {

            Type type = value.GetType();

            MemberInfo[] memberInfo = type.GetMember(value.ToString());

            var attributes = memberInfo[0].GetCustomAttributes(typeof(T), false);

            return (T)attributes.FirstOrDefault();

        }

    }

​

    public class Model

    {

        [Key]

        //[DatabaseGenerated(DatabaseGeneratedOption.None)]

        public int Id { get; set; }

        public ItemType Type { get; set; }

    }

​

    public enum ItemType

    {

        [Description("s")]

        Floor,

        [Description("i")]

        Wall

    }

}