TempData in asp.net mvc

• TempData is a dictionary object derived from TempDataDictionary.
• TempData provide communication between Controller action and it's corresponding view by tranfering and maintaing data.
• The tempdata is retained not only for current request but also retained in case of redirection. It will live till redirected view is fully loaded. 

Example demonstrating the use of TempData:

EmployeeController actions

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using Firstmvcapplication.Models;
namespace Firstmvcapplication.Controllers
{
    public class EmployeeController : Controller
    {

        public ActionResult tempemployee()
        {
            Employee emp = new Employee
            {
                Empid = 1,
                Empname = "suraj"
            };
            TempData["employee"] = emp;
            return RedirectToAction("permanentemployee");
        }
        public ActionResult permanentemployee()
        {
            int a = 0;
            Employee employee = TempData["employee"] as Employee;
            return View(employee);
        }

    }
}

EmployeeModels

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace Firstmvcapplication.Models
{
    public class Employee
    {
        public String Empname { get; set; }
        public int Empid { get; set; }
    }
}

permanentemployee.cshtml

@model Firstmvcapplication.Models.Employee
@{
    ViewBag.Title = "permanentemployee";
}

<div>
     @Html.DisplayNameFor(Model => Model.Empid)
     @Html.DisplayFor(Model => Model.Empid)
</div>
<div>
     @Html.DisplayNameFor(Model => Model.Empname)
     @Html.DisplayFor(Model => Model.Empname)
</div>

Output:

Empid 1

Empname suraj

Explanation:

In controller action two action tempemployee() and permanentemployee() is created. In action tempemployee() tempdata for employee is created and this action redirect to another action named permanentemployee(). In permanentemployee() tempdata from tempemployee() is converted and assigned to a variable employee,this variable is passed to corresponding view. In permanentemployee view data of tempdata is displayed. Thus tempdata retains value till redirected view is fully loaded.