public IActionResult DeleteSupplier(int id, IEnumerable <Reagent> reagents = null)
        {
            var supplier = _context.Suppliers.FirstOrDefault(s => s.ID == id);

            if (supplier == null)
            {
                return(NotFound());
            }
            if (reagents != null)
            {
                foreach (Reagent agent in reagents)
                {
                    _reagentsRepository.RemoveReagent(agent.Id);
                }
            }
            ;
            _context.Remove(supplier);
            _context.SaveChanges();
            var routeValue = new RouteValueDictionary(new { action = "Index", controller = "Suppliers" });

            return(RedirectToRoute(routeValue));
        }