Show a message through a controller “Attendance is already marked”

Question

I'm working on online attendance portal, In which I've set a condition in a controller that user can't marked attendance twice a day. They are only allowed to mark attendance once per day. So I want to show a message on view page "Create" that "Attendance is already marked" if employee is marking the attendance second time on a same date. I've set an alert message but I want to show a message on view page from where employee is marking the attendance .I've searched it a lot but can't find any better one.

 

Here's my Controller Code

[Authorize]
public ActionResult Create()
{
Employee employee = JsonConvert.DeserializeObject<Employee>(User.Identity.Name);
return View(new Attendance() { Emp_Id = employee.Emp_Id });
}
[HttpPost]
public ActionResult Create(Attendance attendance)
{
if (ModelState.IsValid)
{
try
{
var attdate = attendance.Date;
var nextdate = attdate.AddDays(1);
var id = Convert.ToInt32(Session["UserID"]);
var isExist = db.Attendance.FirstOrDefault(i => i.Emp_Id == id && i.Date == attdate && i.Date < nextdate);
if (isExist != null)
{
//Here i set the alert but i want to show message on view page.
return Content("<script language='javascript' type='text/javascript'>alert('Your Attendance is Already Marked');</script>");
}
else
{
//var res = tempDate.Date;
db.Attendance.Add(attendance);
db.SaveChanges();
}
}
catch (Exception ex)
{
Console.WriteLine(ex.InnerException.Message);
}
}
return RedirectToAction("Index", "Attendance");
}