What Is ViewData In ASP.Net MVC

In ASP.Net MVC Application, mostly we have to send data from the controller to a view, so in this blog we are going to learn about how we can pass data from controller to view.

Passing Data From A Controller To A View In ASP.Net MVC

In an ASP.NET MVC application, a controller typically performs the business logic of the application and needs to return the result to the user through a view.

You can use the following objects to pass data between controller and view:

1. ViewData
2. ViewBag
3. TempData

What Is ViewData ?

• ViewData passes data from a controller to a view.
• ViewData is a dictionary of objects that is derived from the ViewDataDictionary class.

Some of the characteristics of ViewData are as follows:

• The life of a ViewData object exists only during the current request.
• The value of ViewData becomes null if the request is redirected.
• ViewData requires typecasting when you use complex data type to avoid error.

The general syntax of ViewData is as follows:

ViewData[“<Key>”] = <Value>;

where,

• Key: Is a String value to identify the object present in ViewData.
• Value: Is the object present in ViewData. This object may be a String, object, list, array or a different type, such as int, char, float, double DateTime etc.

Note: ViewData does not provide compile time error checking. For Example- if you mis-spell keys you wouldn’t get any compile time errors. You get to know about the error only at runtime.

Source Code Of HomeController

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using ViewDataDemo.Models;

namespace ViewDataDemo.Controllers
{
    public class HomeController : Controller
    {
        // GET: Home
        public ActionResult Index()
        {
            ViewData["Message"] = "Message from View Data !!";
            ViewData["CurrentTime"] = DateTime.Now.ToLongTimeString();

            string[] Fruits = {"Apple","Banana","Grapes","Orange" };
            ViewData["FruitsArray"] = Fruits;

            ViewData["SportsList"] = new List<string>()
            {
                "Cricket",
                "Hockey",
                "Football",
                "Volley Ball"
            };

            Employee Ali = new Employee();
            Ali.EmpID = 11;
            Ali.EmpName = "Ali Khan";
            Ali.EmpDesignation = "Manager";

            ViewData["Employee"] = Ali;

            return View();
        }
    }
}

Source Code Of Index.cshtml – View

@{
    ViewBag.Title = "Index";
}

<h2>Index</h2>

<h2>@ViewData["Message"] </h2>
<h2>@ViewData["CurrentTime"]</h2>

<ul>
    @{ 
        foreach (string i in (string[])ViewData["FruitsArray"])
        {
            <li>@i</li>
        }
    }
</ul>

<ul>
    @{
        foreach (string i in (List<string>)ViewData["SportsList"])
        {
            <li>@i</li>
        }
    }
</ul>

@{ 
    var a = (ViewDataDemo.Models.Employee)ViewData["Employee"];
}

<p>@a.EmpID</p>
<p>@a.EmpName</p>
<p>@a.EmpDesignation</p>