public async Task <IActionResult> Create([Bind("ID,groupName,TrainingDay,TrainingTime")] Groups groups)
        {
            if (ModelState.IsValid)
            {
                _context.Add(groups);
                await _context.SaveChangesAsync();

                groups.AddNewGroupToList(groups.groupName);
                return(RedirectToAction(nameof(Index)));
            }
            return(View(groups));
        }