public ActionResult Create(EmployeeViewModel vm)
        {
            if(ModelState.IsValid)
            {
                var dpt = _db.Departments.Single(x => x.DepartmentId == vm.DepartmentId);
                var newEmployee = new Employee();
                newEmployee.Name = vm.Name;
                newEmployee.HireDate = vm.HireDate;
                dpt.Employees.Add(newEmployee);

                _db.Save();

                return RedirectToAction("Details", "Department", new { id = vm.DepartmentId });
            }
            return View(vm);
        }
        public ActionResult Create(int departmentId)
        {
            var vm = new EmployeeViewModel();

            return View(vm);
        }