Earlier today Scott Guthrie announced the ASP.NET MVC 3 - Release Candidate 2. I installed the new version right after the announcement since I was eager to see the new features. Among other cool features included in this release candidate, there is a new ViewBag
dynamic which can be used to pass
data from Controllers to Views same as you use ViewData[] dictionary. What is great and nice about ViewBag (despite the name) is that its a
dynamic type which means you can dynamically get/set values and add any number of additional fields without need of strongly-typed classes. In order to see the difference, please take a look at the following examples. Example - Using ViewData Controller public ActionResult Index() { List<string> colors = new List<string>(); colors.Add("red"); colors.Add("green"); colors.Add("blue"); ViewData["listColors"] = colors; ViewData["dateNow"] = DateTime.Now; ViewData["name"] = "Hajan"; ViewData["age"] = 25; return View(); } View (ASPX View Engine) <p> My name is <b><%: ViewData["name"] %></b>, <b><%: ViewData["age"] %></b> years old. <br /> I like the following colors: </p> <ul id="colors"> <% foreach (var color in ViewData["listColors"] as List<string>){ %> <li> <font color="<%: color %>"><%: color %></font> </li> <% } %> </ul> <p> <%: ViewData["dateNow"] %> </p> (I know the code might look cleaner with Razor View engine, but it doesn’t matter right? ;) ) Example - Using ViewBag Controller public ActionResult Index() { List<string> colors = new List<string>(); colors.Add("red"); colors.Add("green"); colors.Add("blue"); ViewBag.ListColors = colors; //colors is List ViewBag.DateNow = DateTime.Now; ViewBag.Name = "Hajan"; ViewBag.Age = 25; return View(); } You see the difference? View (ASPX View Engine) <p> My name is <b><%: ViewBag.Name %></b>, <b><%: ViewBag.Age %></b> years old. <br /> I like the following colors: </p> <ul id="colors"> <% foreach (var color in ViewBag.ListColors) { %> <li> <font color="<%: color %>"><%: color %></font> </li> <% } %> </ul> <p> <%: ViewBag.DateNow %> </p> In my example now I don’t need to cast ViewBag.ListColors as List<string> since ViewBag is
dynamic type! On the other hand the ViewData[“key”] is object.I would like to note that if you use ViewData["ListColors"] = colors; in your Controller, you can retrieve it in the View by using ViewBag.ListColors. And the result in both cases is Hope you like it! Regards, Hajan
