In this article I will explain with an example, the Similarities and Differences of ViewData, ViewBag and TempData in ASP.Net MVC.
ViewData, ViewBag and TempData are used for transferring data and objects between Controller to View or from one Controller to another in ASP.Net MVC.
ViewData
1. ViewData is derived from the ViewDataDictionary class and is basically a Dictionary object i.e. Keys and Values where Keys are String while Values will be objects.
2. Data is stored as Object in ViewData.
3. While retrieving, the data it needs to be Type Casted to its original type as the data is stored as objects and it also requires NULL checks while retrieving.
4. ViewData is used for passing value from Controller to View.
5. ViewData is available only for Current Request. It will be destroyed on redirection.
Example
In the below example, a string value is set in the ViewData object in Controller and it is then displayed in View.
Controller
public class FirstController : Controller
{
// GET: First
public ActionResult Index()
{
ViewData["Message"] = "Hello MVC!";
return View();
}
}
View
<html>
<head>
<meta name="viewport" content="width=device-width"/>
<title>Index</title>
</head>
<body>
<div>
@ViewData["Message"]
</div>
</body>
</html>
ViewBag
1. ViewBag is a Wrapper built around ViewData.
2. ViewBag is a dynamic property and it makes use of the C# 4.0 dynamic features.
3. While retrieving, there is no need for Type Casting data.
4. ViewBag is used for passing value from Controller to View.
5. ViewBag is available only for Current Request. It will be destroyed on redirection.
Example
In the below example, a string value is set in the ViewBag object in Controller and it is then displayed in View.
Controller
public class FirstController : Controller
{
// GET: First
public ActionResult Index()
{
ViewBag.Message = "Hello MVC!";
return View();
}
}
View
<html>
<head>
<meta name="viewport" content="width=device-width"/>
<title>Index</title>
</head>
<body>
<div>
@ViewBag.Message
</div>
</body>
</html>
TempData
1. TempData is derived from the TempDataDictionary class and is basically a Dictionary object i.e. Keys and Values where Keys are String while Values will be objects.
2. Data is stored as Object in TempData.
3. While retrieving, the data it needs to be Type Casted to its original type as the data is stored as objects and it also requires NULL checks while retrieving.
4. TempData can be used for passing value from Controller to View and also from Controller to Controller.
5. TempData is available for Current and Subsequent Requests. It will not be destroyed on redirection.
Example
In the below example, a string value is set in the TempData object in Controller and it is redirected to another Controller and finally it is displayed in View.
First Controller
public class FirstController : Controller
{
// GET: First
public ActionResult Index()
{
TempData["Message"] = "Hello MVC!";
return new RedirectResult(@"~\Second\");
}
}
Second Controller
public class SecondController : Controller
{
// GET: Second
public ActionResult Index()
{
return View();
}
}
View of Second Controller
<html>
<head>
<meta name="viewport" content="width=device-width"/>
<title>Index</title>
</head>
<body>
<div>
@TempData["Message"];
</div>
</body>
</html>
