Return to same View if Data is not Found and Display Not Found Message in the same View - asp.net-mvc

Question

I have Search View Where user enters Employee ID, Upon Clicking Button an Action Method is Executed and user is Redirected to Employee Details View.
If Employee Id not Matches I want to Retain the Same Search View and display a Label with Employee Details not Found Message in MVC,
Please help on doing the above Fucntionality in my Controller.
[HttpGet]
public async Task<ActionResult> Details(string firstName)
{
var empDetails = await _context.EmpDetails
.FirstOrDefaultAsync(m => m.FirstName == firstName);
if (empDetails == null)
{
// ???
}
return View(empDetails);
}

Answer 1

It is good practice to have ViewModel classes. Make one, and use it to transfer domain objects and messages to your view. Like this:
class EmpDetailsViewModel
{
public EmpDetail Emp { get;set; }
public string Message { get;set; }
}
[HttpGet]
public async Task<ActionResult> Details(string firstName)
{
var vm = new EmpDetailsViewModel();
var empDetails = await _context.EmpDetails
.FirstOrDefaultAsync(m => m.FirstName == firstName);
if (empDetails == null)
{
vm.Message = "Employee not found (or whatever)"
}
else
{
vm.Emp = empDetails;
}
return View(vm);
}
Then, in your view, just do
if (Model.Emp == null)
{
<span>#Model.Message</span>
}
else
{
<div>Emp details stuff </div>
}

Answer 2

What I understand is you want to return a message when Employee is not found.
Try this
[HttpGet]
public async Task<ActionResult> Details(string firstName)
{
var empDetails = await _context.EmpDetails
.FirstOrDefaultAsync(m => m.FirstName == firstName);
if (empDetails == null)
{
return Content("Employee not found");
}
return View(empDetails);
}
In view extract the message from the response.
--Edit
You can do an Ajax call like below to this action method
<script type="text/javascript">
$(function () {
$("#btnGetDetails").click(function () {
$.ajax({
type: "GET",
url: "/Employee/Details",
data: '{firstName: "' + $("#txtSearch").val() + '" }',
contentType: "application/json; charset=utf-8",
dataType: "json",
success: function (response) {
alert(response.responseText);
},
failure: function (response) {
alert(response.responseText);
},
error: function (response) {
alert(response.responseText);
}
});
});
});
</script>
success call back will be triggered and the message will be available in the view. (Didn't test the script)