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What is ViewData, ViewBag and TempData? – MVC options for passing data between current and subsequent request

, 15 Oct 2012 CPOL
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ASP.NET MVC offers us three options ViewData, VieBag and TempData for passing data from controller to view and in next request. ViewData and ViewBag are almost similar and TempData performs additional responsibility. Lets discuss or get key points on those three objects: Similarities bet


ASP.NET MVC offers us three options ViewData, VieBag and TempData for passing data from controller to view and in next request. ViewData and ViewBag are almost similar and TempData performs additional responsibility. Lets discuss or get key points on those three objects:

Similarities between ViewBag & ViewData :

  1. Helps to maintain data when you move from controller to view.
  2. Used to pass data from controller to corresponding view.
  3. Short life means value becomes null when redirection occurs. This is because their goal is to provide a way to communicate between controllers and views. It’s a communication mechanism within the server call.

Difference between ViewBag & ViewData:

  1. ViewData is a dictionary of objects that is derived from ViewDataDictionary class and accessible using strings as keys.
  2. ViewBag is a dynamic property that takes advantage of the new dynamic features in C# 4.0.
  3. ViewData requires typecasting for complex data type and check for null values to avoid error.
  4. ViewBag doesn’t require typecasting for complex data type.

ViewBag & ViewData Example:

public ActionResult Index()
{
    ViewBag.Name = "Monjurul Habib";
    return View();
}
public ActionResult Index()
{
    ViewData["Name"] = "Monjurul Habib";
    return View();
} 

In View:

@ViewBag.Name 
@ViewData["Name"] 

TempData:

TempData is also a dictionary derived from TempDataDictionary class and stored in short lives session and it is a string key and object value. The difference is that the life cycle of the object. TempData keep the information for the time of an HTTP Request. This mean only from one page to another. This also work with a 302/303 redirection because it’s in the same HTTP Request. Helps to maintain data when you move from one controller to other controller or from one action to other action. In other words when you redirect, “Tempdata” helps to maintain data between those redirects. It internally uses session variables. Temp data use during the current and subsequent request only means it is use when you are sure that next request will be redirecting to next view. It requires typecasting for complex data type and check for null values to avoid error. generally used to store only one time messages like error messages, validation messages.

public ActionResult Index()
{
  var model = new Review()
            {
                Body = "Start",
                Rating=5
            };
    TempData["ModelName"] = model;
    return RedirectToAction("About");
}
<pre><pre lang="cs">public ActionResult About()
{
    var model= TempData["ModelName"];
    return View(model);
}
The last mechanism is the Session which work like the ViewData, like a Dictionary that take a string for key and object for value. This one is stored into the client Cookie and can be used for a much more long time. It also need more verification to never have any confidential information. Regarding ViewData or ViewBag you should use it intelligently for application performance. Because each action goes through the whole life cycle of regular asp.net mvc request. You can use ViewData/ViewBag in your child action but be careful that you are not using it to populate the unrelated data which can pollute your controller.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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About the Author

Monjurul Habib
Software Developer (Senior)
Bangladesh Bangladesh
A life-long-learner, maker and soft music fan. Likes building things to solve problems. Lives in Dhaka with wife and wonderful, smart kid and works as a Senior Software Engineer in applications architecture team.
 
He has years of successful records serving mid and large scale .NET applications. Have a wide range of experience working in domestic and international client environment. Expertise in different areas of software development life cycles and Software Architecture.
 
I am always looking for new information and value your feedback (especially where I got something wrong!).
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Comments and Discussions

 
General[My vote of 2] TempData explanation misleading PinmemberDominik Raniszewski20-Oct-14 18:35 
GeneralMy vote of 3 Pinmembersoftskiper10-Aug-14 22:05 
QuestionVote PinmemberMember 809692630-Jul-14 5:51 
GeneralMy vote of 4 PinmemberManoj B. Kalla21-Jul-14 20:15 
GeneralMy vote of 3 PinmemberAli Murad25-May-14 22:23 
GeneralMy vote of 2 PinmemberAndrija Juric24-Apr-14 0:01 
GeneralMy vote of 5 PinmemberPham Hong Sang11-Apr-14 17:02 
GeneralThanks PinmemberMd.Mithun20-Feb-14 22:56 
NewsSomeone has copied your code PinmemberSubhadeep Mitra27-Jan-14 20:33 
QuestionWhy do these exist? PinmemberMember 80474894-Dec-13 4:37 
QuestionWhat is an HTTP Request? PinmemberColin Angus Mackay3-Dec-13 0:19 
AnswerRe: What is an HTTP Request? Pinmembersaineshwar9-Apr-14 21:44 
GeneralUsing Session["myThing"] PinmemberRoger Tranchez23-Oct-13 3:30 
Questionthanks, not explained everywhere PinmemberMember 1030591229-Sep-13 22:25 
Question[My vote of 2] Session is not stored in a cookie Pinmembermorzel20-Sep-13 6:10 
QuestionScope of ViewData and ViewBag and TempData PinprofessionalAntariksh Verma15-Sep-13 21:54 
AnswerRe: Scope of ViewData and ViewBag and TempData PinmemberImran Abdul Ghani9-Jul-14 21:26 
GeneralMy vote of 5 PinmemberMember 1022250122-Aug-13 0:07 
QuestionHi! PinmemberNewbie201420-Aug-13 4:47 
AnswerRe: Hi! PinprofessionalMonjurul Habib20-Aug-13 20:40 
GeneralMy vote of 5 Pinmembermanoj kumar choubey7-Aug-13 21:06 
GeneralRe: My vote of 5 PinprofessionalMonjurul Habib12-Aug-13 12:46 
GeneralMy vote of 3 Pinmembermayank.gpt129-Jul-13 3:54 
GeneralRe: My vote of 3 PinprofessionalMonjurul Habib1-Aug-13 11:09 
GeneralCrisp and Clear Pinmembermynutshell18-Jul-13 21:34 

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