public static AuthUserX FindByUsername(this IReadOnlyDbContext db, string username)
 {
     return(db.FindFirst <AuthUserX>(u => u.Username == username));
 }
        public static City GetMainCity(IReadOnlyDbContext db)
        {
            var mainCitySettings = db.FindFirst <Settings>(s => s.Key == "MainCity");

            return(db.FindById <City>(mainCitySettings.Value));
        }