What is ViewData in ASP .Net MVC C#?

ViewData is a dictionary of objects stored and retrieved using strings as keys. It is used to transfer data from controller to view. Since ViewData is a dictionary, it Contains key-value pairs, where each key must be a string. View data transfer only Data goes from controller to view and vice versa. Valid only during the current request.

Storing data in ViewData-

ViewData["countries"] = countriesList;

Retrieving data from ViewData-

string country = ViewData["MyCountry"].ToString();

ViewData does not provide compile-time error checking . For example, if we misspell keyname we won't get any compile time errors. we will learn about The error only occurs at runtime.

Controller

Example

using System.Collections.Generic;
using System.Web.Mvc;
namespace DemoMvcApplication.Controllers{
   public class HomeController : Controller{
      public ViewResult Index(){
         ViewData["Countries"] = new List<string>{
            "India",
            "Malaysia",
            "Dubai",
            "USA",
            "UK"
         };
         return View();
      }
   }
}

View

@{
   ViewBag.Title = "Countries List";
}
<h2 id="Countries-List">Countries List</h2>
<ul>
@foreach(string country in (List<string>)ViewData["Countries"]){
   <li>@country</li>
}
</ul>

Output

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