public ActionResult Create(CreateEmployeeViewModel viewModel)
        {
            if (ModelState.IsValid)
            {
                var department = _db.Departments.Single<Department>(c => c.Id == viewModel.DepartmentId);
                department.Employees.Add(new Employee()
                {
                    Name = viewModel.Name,
                    HireDate = viewModel.HireDate
                });

                _db.Save();
                return RedirectToAction("Details", "Department", new { id = viewModel.DepartmentId });
            }
            return View(viewModel);
        }
 public ActionResult Create(int departmentId)
 {
     var model = new CreateEmployeeViewModel();
     model.DepartmentId = departmentId;
     return View(model);
 }