public async Task <ActionResult <IEnumerable <DetailViewModel> > > GetScheduleForGroup(int groupId, int?semestr) { if (!semestr.HasValue || semestr < 0 || semestr > 3) { semestr = DateTimeHelper.GetCurrentSemestr(); } return(Ok((await _detailService.GetScheduleForGroup(groupId, semestr.Value)).Select(x => x.ToViewModel()))); }