What is View Bag object in MVC?

Answer 1

The ViewBag object is a wrapper around the ViewData object that allows you to create dynamic properties for the ViewBag. (ViewData is a dictionary object that you put data into, which then becomes available to the view. ViewData is a derivative of the ViewDataDictionary class, so you can access by the familiar "key/value" syntax.)

Both the ViewData and ViewBag objects are great for accessing extra data (i.e., outside the data model), between the controller and view. Since views already expect a specific object as their model, this type of data access to extra data, MVC implements it as a property of both views and controllers, making usage and access to these objects easy.

Please see the following code sample, which populates a featured product object that a view renders as in a bakery's home page:

public class HomeController : Controller
{
    // ViewBag & ViewData sample
    public ActionResult Index()
    {
        var featuredProduct = new Product
        {
            Name = "Special Cupcake Assortment!",
            Description = "Delectable vanilla and chocolate cupcakes",
            CreationDate = DateTime.Today,
            ExpirationDate = DateTime.Today.AddDays(7),
            ImageName = "cupcakes.jpg",
            Price = 5.99M,
            QtyOnHand = 12
        };

        ViewData["FeaturedProduct"] = featuredProduct;
        ViewBag.Product = featuredProduct;
        TempData["FeaturedProduct"] = featuredProduct;  

        return View();
    }
}