Question

When a user log in into my application i want to show his name throughout the whole application. I am using the asp.net MVC framework. But what i don’t want is that is have to put in every controller something like:

ViewData['User'] = Session['User']; 

This because you may not repeat yourself. (I believe this is the DRY [Don’t Repeat Yourself] principle of OO programming.) The ViewData[‘User’] is on my masterpage. So my question is, what is a neat way to handle my ViewData[‘User’] on one place?

Answer 1

You can do this fairly easily in either a controller base-class, or an action-filter that is applied to the controllers/actions. In either case, you get the chance to touch the request before (or after) the action does – so you can add this functionality there.

For example:

public class UserInfoAttribute : ActionFilterAttribute {     public override void OnActionExecuting(         ActionExecutingContext filterContext)     {         base.OnActionExecuting(filterContext);         filterContext.Controller.ViewData['user'] = 'Foo';     } } ... [HandleError, UserInfo] public class HomeController : Controller {...} 

(can also be used at the action (method) level)

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or with a common base-class:

public abstract class ControllerBase : Controller {     protected override void OnActionExecuting(         ActionExecutingContext filterContext)     {         ViewData['user'] = 'Bar';         base.OnActionExecuting(filterContext);     } }  [HandleError] public class HomeController : ControllerBase {...}