Asp.Net MVC Techniques to transfer data from Controller to View

Introduction

ASP.NET MVC also provides state management techniques that can help us to maintain the data when redirecting from one page to other page or in the same page after reloading. There are several ways to do this in ASP.NET MVC .

HTTP is a stateless protocol, i.e., each HTTP request does not know about the previous request. If you are redirecting from one page to another page, then you have to maintain or persist your data so that you can access it further.

In Asp.Net MVC there are three ways to pass/store data between the controllers and views.

Description

ViewData

1. ViewData is used to pass data from controller to view
2. It is derived from ViewDataDictionary class
3. It is available for the current request only
4. Requires typecasting for complex data type and checks for null values to avoid error
5. If redirection occurs, then its value becomes null

ViewBag

1. ViewBag is also used to pass data from the controller to the respective view
2. ViewBag is a dynamic property that takes advantage of the new dynamic features in C# 4.0
3. It is also available for the current request only
4. If redirection occurs, then its value becomes null
5. Doesn’t require typecasting for complex data type

TempData

1. TempData is derived from TempDataDictionary class
2. TempData is used to pass data from the current request to the next request
3. It keeps the information for the time of an HTTP Request. This means only from one page to another. It helps to maintain the data when we move from one controller to another controller or from one action to another action
4. It requires typecasting for complex data type and checks for null values to avoid error. Generally, it is used to store only one time messages like the error messages and validation messages 

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. ViewBag is a dynamic property (dynamic keyword which 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 Code

Controller Code:

public ActionResult Index() 
{ 
      List<string> Student = new  List<string>(); 
      Student.Add("Satya1"); 
      Student.Add("Satya11"); 
      Student.Add("Satya111"); 
     
      ViewData["Student"] = Student; 
      return View(); 
}

View code:

1.<ul>  
2.    <% foreach (var student in ViewData["Student"] as List<string>)  
3.        { %>  
4.    <li><%: student%></li>  
5.    <% } %>  
6.</ul>

ViewBag Code

Controller Code:

01.public ActionResult Index()  
02.{  
03.      List<string> Student = new  List<string>();  
04.      Student.Add("Satya1");  
05.      Student.Add("Satya11");  
06.      Student.Add("Satya111");  
07.    
08.      ViewBag.Student = Student;  
09.      return View();  
10.}

View code:

1.<ul>  
2.    <% foreach (var student in ViewBag.Student)  
3.        { %>  
4.    <li><%: student%></li>  
5.    <% } %>  
6.</ul>

TempData is a dictionary which is derived from TempDataDictionary class. TempData is stored data just like live session for short time. TempData keeps data for the time of HTTP Request, which means that it holds data between two consecutive requests. TempData helps us to transfer data between controllers or between actions. TempData internally use Session variables. Note that TempData is only work during the current and subsequent request. It is generally used to store one time messages. With the help of the TempData.Keep() method we can keep value in TempData object after request completion.

TempData Code

Controller Code:

01.public ActionResult Index()  
02.{  
03.    List<string> Student = new  List<string>();  
04.    Student.Add("Satya1");  
05.    Student.Add("Satya11");  
06.    Student.Add("Satya111");  
07.    
08.    TempData["Student"] = Student;  
09.    return View();  
10.}

View code:

<ul>  
    <% foreach (var student in TempData["Student"] as List<string>)  
        { %>  
    <li><%: student%></li>  
    <% } %>  
</ul>

ViewData	ViewBag	TempData
It is Key-Value Dictionary collection	It is a type object	It is Key-Value Dictionary collection
ViewData is a dictionary object and it is property of ControllerBase class	ViewBag is Dynamic property of ControllerBase class.	TempData is a dictionary object and it is property of controllerBase class.
ViewData is Faster than ViewBag	ViewBag is slower than ViewData	NA
ViewData is introduced in MVC 1.0 and available in MVC 1.0 and above	ViewBag is introduced in MVC 3.0 and available in MVC 3.0 and above	TempData is also introduced in MVC1.0 and available in MVC 1.0 and above.
ViewData also works with .net framework 3.5 and above	ViewBag only works with .net framework 4.0 and above	TempData also works with .net framework 3.5 and above
Type Conversion code is required while enumerating	In depth, ViewBag is used dynamic, so there is no need to type conversion while enumerating.	Type Conversion code is required while enumerating
Its value becomes null if redirection has occurred.	Same as ViewData	TempData is used to pass data between two consecutive requests.
It lies only during the current request.	Same as ViewData	TempData only works during the current and subsequent request

SUMMARY

1. ViewData, ViewBag and TeampData for passing data from controller to view and in next request.
2. ViewData and ViewBag are almost similar and it helps us to transfer the data from controller to view .
3. TempData also works during the current and subsequent requests.