Skip to main content

ViewData, ViewBag and TempData in MVC


ViewData, ViewBag and TempData in MVC explained


ViewBag and ViewData are used to pass the data from Controller action to View and TempData is used to pass the data from action to another action or one Controller to another Controller.

ViewData and ViewBag are used for the same purpose that is, to transfer data from controller to view.  ViewData is nothing but a dictionary of objects and it is accessible by string as key. ViewData is a property of controller that exposes an instance of the 

ViewDataDictionary class. ViewBag is very similar to ViewData, but ViewBag is a dynamic property (dynamic keyword is introduced in .net framework 4.0). ViewBag is able to set and get value dynamically and able to add any number of additional fields without converting it to strongly typed. ViewBag is just a wrapper around the ViewData.

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.       We need to cast data back to its original type since the data is stored as object in ViewData. Also it required NULL checking 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 example that follows, a string value is set in the ViewData object in Controller and it is then displayed in View.

Controller

public class CsharpnaijaController : Controller
{
    // GET: Csharpnaija
    public ActionResult Index()
    {
        ViewData["Message"] = "C# Naija, Hello!";
        return View();
    }
}

View

<html>
<head>
    <meta name="viewport" content="width=device-width"/>
    <title>Index</title>
</head>
<body>
    <div>
        @ViewData["Message"]
    </div>
</body>
</html>

ViewBag

ViewBag is a dynamic object to pass the data from Controller to View. And, this will pass the data as a property of object ViewBag. And we have no need to typecast to read the data or for null checking. The scope of ViewBag is permitted to the current request and the value of ViewBag will become null while redirecting.

Example

Controller

public class CsharpnaijaController : Controller
{
    // GET: First
    public ActionResult Index()
    {
        ViewBag.Message = "C# Naija, Hello";
        return View();
    }
}

View

<html>
<head>
    <meta name="viewport" content="width=device-width"/>
    <title>Index</title>
</head>
<body>
    <div>
        @ViewBag.Message
    </div>
</body>
</html>

TempData

TempData is a dictionary object to pass data from one action to other action in the same Controller or different Controller. Usually, TempData object will be stored in a session object. Tempdata is also required to typecast and null check before reading data from it. TempData scope is limited to the next request and if we want Tempdata to be available even further, we should use Keep and peek.

Example

In the following example, a string value is set in the TempData object in Controller and it is redirected to another Controller and finally displayed in View.

Employee Controller

public class  EmployeeController : Controller
{
    // GET: Employee
    public ActionResult Index()
    {
        TempData["Message"] = "Hello, C# Naija ";
        return new RedirectResult(@"~\Department\");
    }
}

Department Controller


public class DepartmentController : Controller
{
    // GET: Department
    public ActionResult Index()
    {
        return View();
    }
}

View of Department Controller


<html>
<head>
    <meta name="viewport" content="width=device-width"/>
    <title>Index</title>
</head>
<body>
    <div>
        @TempData["Message"];
    </div>
</body>
</html>

I hope this article helped you understand, the concept of ViewData, ViewBag and TempData.

This article referenced the work of Mudassar Khan, SATISH KUMAR and JIGNESHTRIVEDI



Labels:
Location: Abuja, Nigeria

Comments

Post a Comment

Popular posts from this blog

Classes in C# Explained

C# Class Explained A class is nothing but an encapsulation of properties and methods that are used to represent a real-time entity, as explained by Guru99 . For instance, if you want to work with Guest’s data as in our previous DataDriven Web application . The properties of the Guest would be the Id, GuestName, Address, Phone number etc of the Guest. The methods would include the entry and modification of Guest data. All of these operations can be represented as a class in C# as shown below. using System; namespace CsharpnaijaClassTutorial {     public class Guest     {         public int Id { get ; set ; }         public string GuestName { get ; set ; }         public string Address { get ; set ; }         public string WhomToSee { get ; set ; }     ...
1 comment
Read more

ASP.NET MVC Views

Views in ASP.NET MVC Application explained Find a related article By  Steve Smith  and  Luke Latham from Microsoft Corporation here In the Model-View-Controller (MVC) pattern, the  view  handles the application's data presentation and user interaction. A view is an HTML template with embedded  Razor markup . Razor markup is code that interacts with HTML markup to produce a webpage that's sent to the client. In ASP.NET MVC, views are  .cshtml  files that use the  C# programming language  in Razor markup. Usually, view files are grouped into folders named for each of the application's  controllers . The folders are stored in a  Views  folder at the root of the application as shown: The  Home  controller is represented by a  Home  folder inside the  Views  folder.  The  Home  folder contains the views for the  About ,  Contact , and  Index...
Post a Comment
Read more

ASP.NET MVC Routing

ASP.NET MVC Routing ASP.NET MVC routing is a pattern matching system that is responsible for mapping incoming browser requests to specified MVC controller actions. When the ASP.NET MVC application launches then the application registers one or more patterns with the framework's route table to tell the routing engine what to do with any requests that matches those patterns. When the routing engine receives a request at runtime, it matches that request's URL against the URL patterns registered with it and gives the response according to a pattern match. Routing pattern is as follows A URL is requested from a browser, the URL is parsed (that is, break into controller and action), the parsed URL is compared to registered route pattern in the framework’s route table, if a route is found, its process and send response to the browser with the required response, otherwise, the HTTP 404 error is send to the browser. Route Properties ASP.NET MVC routes are res...
Post a Comment
Read more