public async Task <IActionResult> Index([FromQuery] int?age = null) { GuestListResponse response; if (age == null) { response = await _guestService.GetGuestsAsync(); } else { response = await _guestService.GetGuestsByAgeAsync(age.Value); } if (!response.Result) { _logger.LogInformation($"An error occured during retrieving guests list."); return(BadRequest(response)); } _logger.LogInformation("Guests list successfully retrieved."); return(new OkObjectResult(response)); }