MVC-ViewData vs ViewBag vs TempData

In ASP.NET MVC, ViewData, ViewBag, and TempData are used to pass data between controllers and views, but they each have their unique characteristics.

ViewData

1. It's a dictionary object that is derived from ViewDataDictionary.
2. Data is accessed using string keys.
3. It's useful for passing data from the controller to the view.
4. Data is available only during the current request.

public ActionResult Index()
{
    ViewData["Message"] = "Hello from ViewData!";
    return View();
}

//View

<p>@ViewData["Message"]</p>

ViewBag

1. It's a dynamic object that uses the ExpandoObject under the hood.
2. Easier syntax compared to ViewData as it doesn't require casting.
3. Also used for passing data from the controller to the view.
4. Data is available only during the current request.

public ActionResult Index()
{
    ViewBag.Message = "Hello from ViewBag!";
    return View();
}

//View
<p>@ViewBag.Message</p>

TempData

1. It's a dictionary object derived from TempDataDictionary.
2. Stores data that is needed for more than a single request, useful for redirection.
3. Data persists until it is read, or the session expires.
4. Data is accessed using string keys.

public ActionResult Index()
{
    TempData["Message"] = "Hello from TempData!";
    return RedirectToAction("NextAction");
}

public ActionResult NextAction()
{
    string message = TempData["Message"] as string;
    ViewBag.Message = message;
    return View();
}

//View

<p>@ViewBag.Message</p>

Here's a comparison of ViewData, ViewBag, and TempData in tabular form.