ViewBag, ViewData and TempData

Question

Could any body explain, when to use

1. TempData
2. ViewBag
3. ViewData

I have a requirement, where I need to set a value in a control

Answer 1

TempData in Asp.Net MVC is one of the very useful feature. It is used to pass data from current request to subsequent request. In other words if we want to send data from one page to another page while redirection occurs, we can use TempData, but we need to do some consideration in code to achieve this feature in MVC. Because the life of TempData is very short and lies only till the target view is fully loaded. But, we can use Keep() method to persist data in TempData.

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Answer 2

void Keep()

Calling this method with in the current action ensures that all the items in TempData are not removed at the end of the current request.

    @model MyProject.Models.EmpModel;
    @{
    Layout = "~/Views/Shared/_Layout.cshtml";
    ViewBag.Title = "About";
    var tempDataEmployeet = TempData["emp"] as Employee; //need typcasting
    TempData.Keep(); // retains all strings values
    } 

void Keep(string key)

Calling this method with in the current action ensures that specific item in TempData is not removed at the end of the current request.

    @model MyProject.Models.EmpModel;
    @{
    Layout = "~/Views/Shared/_Layout.cshtml";
    ViewBag.Title = "About";
    var tempDataEmployeet = TempData["emp"] as Employee; //need typcasting
    TempData.Keep("emp"); // retains only "emp" string values
    }