Code First Enumerations put into Lookup Tables

Question

I have worked in a lot of shops where they ran a Database First Model so Lookup Tables were always required. Your lookup table had to match your Enums so that you kept database

Answer 1

If you aren't looking to muddy up your context but still want your enums in the database for troubleshooting & manual queries. It's also not ideal, but you can do an at-once migration when you need it. Obviously there's some cleanup and tweaking to be done which may vary depending on your use case.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Text.RegularExpressions;
using LookupExample.Data;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;

namespace LookupExample.Areas.Admin.Controllers
{
    // [Authorize]
    [Area("Admin")]
    public class SetupController : Controller
    {
        private ApplicationDbContext _db;

        public SetupController(ApplicationDbContext dbContext)
        {
            _db = dbContext;
        }

        public IActionResult Enums()
        {
            var enums = Assembly.GetExecutingAssembly().GetTypes()
                .Where(ttype => ttype.IsEnum && ttype.IsPublic && ttype.Namespace.StartsWith("LookupExample.Models"));

            var dictionary = enums.ToDictionary(EnumTableName, EnumDictionary);

            if (dictionary.Count <= 0) return Json(dictionary);

#pragma warning disable EF1000 // Possible SQL injection vulnerability.
            foreach (var kvp in dictionary)
            {
                var table = kvp.Key;
                var tableSql = $"IF OBJECT_ID('{table}', 'U') IS NOT NULL DROP TABLE {table}; CREATE TABLE {table} ( Id int, Val varchar(255));";
                _db.Database.ExecuteSqlCommand(tableSql);

                if (kvp.Value.Count <= 0) continue;

                var insertSql = $"INSERT INTO {table} (Id, Val) VALUES ( @P0, @P1);";
                foreach (var row in kvp.Value)
                {
                    _db.Database.ExecuteSqlCommand(insertSql, row.Key, row.Value);
                }
            }
#pragma warning restore EF1000 // Possible SQL injection vulnerability.

            return Json(dictionary);
        }

        private string EnumTableName(Type eenum)
        {
            var namespaceModifier = Regex.Replace(Regex.Replace(eenum.Namespace, @"^LookupExample\.Models\.?", ""), @"\.?Enums$", "").Replace(".", "_");
            if (namespaceModifier.Length > 0)
            {
                namespaceModifier = namespaceModifier + "_";
            }
            return "dbo.Enum_" + namespaceModifier + eenum.Name; // TODO enum schema?
        }

        private Dictionary EnumDictionary(Type eenum)
        {
            return Enum.GetValues(eenum).Cast().ToDictionary(e => e, e => Enum.GetName(eenum, e));
        }
    }
}