Enums in EF Core

EFCoreEnums.csproj

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>netcoreapp2.2</TargetFramework>
    <RootNamespace>EFCoreEnums</RootNamespace>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="2.2.6" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.Sqlite" Version="2.2.6" />
  </ItemGroup>

</Project>

Program.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.EntityFrameworkCore;

namespace EFCoreEnums
{
    public class Wine
    {
        public int WineId { get; set; }
        public string Name { get; set; }

        public WineVariantId WineVariantId { get; set; }
        public WineVariant WineVariant { get; set; }
    }

    public enum WineVariantId : int
    {
        Red,
        White,
        Rose
    }

    public class WineVariant
    {
        public WineVariantId WineVariantId { get; set; }
        public string Name { get; set; }

        public List<Wine> Wines { get; set; }
    }

    public class WineContext : DbContext
    {
        public DbSet<Wine> Wines { get; set; }
        public DbSet<WineVariant> WineVariants { get; set; }

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            optionsBuilder.UseSqlite("Data Source=wines.db");
        }

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            modelBuilder
                .Entity<Wine>()
                .Property(e => e.WineVariantId)
                .HasConversion<int>();

            modelBuilder
                .Entity<WineVariant>()
                .Property(e => e.WineVariantId)
                .HasConversion<int>();

            modelBuilder
                .Entity<WineVariant>().HasData(
                    Enum.GetValues(typeof(WineVariantId))
                        .Cast<WineVariantId>()
                        .Select(e => new WineVariant()
                        {
                            WineVariantId = e,
                            Name = e.ToString()
                        })
                );
        }
    }

    public static class Program
    {
        public static async Task Main(string[] args)
        {
            using (var db = new WineContext())
            {
                await db.Database.MigrateAsync();

                db.Wines.Add(new Wine
                {
                    Name = "Gutturnio",
                    WineVariantId = WineVariantId.Red,
                });

                db.Wines.Add(new Wine
                {
                    Name = "Ortrugo",
                    WineVariantId = WineVariantId.White,
                });

                await db.SaveChangesAsync();
            }

            using (var db = new WineContext())
            {
                var gutturnio = await db.Wines
                    .AsNoTracking()
                    .Include(w => w.WineVariant)
                    .FirstAsync(w => w.Name == "Gutturnio");
                
                Console.WriteLine($"{gutturnio.Name} is a {gutturnio.WineVariant.Name} wine");
            }
        }
    }
}

This is my answer to this StackOverflow question: How to create a table corresponding to enum in EF Core Code First?

How would this model change if you had a one to many relationship to the Enum? Like what if it was People and Sports (an enum of typical sports), where people could play multiple sports and you wanted to map that relationship through EF?

Hi @rich0726, that would be a many to many relationship, take a look at here: https://docs.microsoft.com/en-us/ef/core/modeling/relationships?tabs=fluent-api%2Cfluent-api-simple-key%2Csimple-key#many-to-many

What changes would we have to do to this, if we need it as a many-to-many relationship, then convert it back to a ICollection of enum(or class with enum as Id)

It should be updated a bit as here: https://gist.github.com/Sergio1C/1f08c203011d42c4fcf7a7e43ff590a5/revisions