If you’re writing an HTML Helper for ASP.NET MVC you may want to do something different based on whether the page that is to be rendered was arrived at via a particular controller or controller action.  I found the following code which does just this in one of the ASP.NET MVC Themes available from the www.asp.net web site (the Dark theme, I believe it’s called).

Note that I’ve already modified this code to work with the new ASP.NET 4 string encoding and the MvcHtmlString type, as I wrote about previously.

public static MvcHtmlString LoginLink(this HtmlHelper helper)

{

    string currentControllerName = 

      (string)helper.ViewContext.RouteData.Values["controller"];

    string currentActionName = 

      (string)helper.ViewContext.RouteData.Values["action"];

    bool isAuthenticated = 

      helper.ViewContext.HttpContext.Request.IsAuthenticated;

    // more stuff here

}

As you can see, the HtmlHelper has a ViewContext property, which allows you to access RouteData and ultimately from there determine the controller and/or action that was used for this request.  Incidentally, you can also use the ViewContext to get to HttpContext and determine whether the request is authenticated as well.

And that’s it!

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