MVC 3 Layout and Controllers

Question

I m building a MVC 3 applications. The application should be able to display a different layout according to the sub domaine (ex: customer1.mysite.com -> layout1; customer2.mysite.com -> layout2; etc...) it will have also a layout for mobile and IE 6.

I have seen that their is the _ViewStart.cshtml that I can leverage to do the logic to set the layout. But what I don't get is where is the controler for that? Should I write all the code in the view?

An other question with layout how to do you factor out the code for the common behaviours? Do you have a controler for that?

And a last one I have seen the concept of areas in asp.net MVC2 is it obsolete now that we have Razor?

Thank you for your help

Fred

Answer 1

While you could do this in the _ViewStart I think that a better way would be to write a custom view engine in which based on the user agent or the domain include a different layout. Then you would have common controllers and views, only the layout will differ.

Answer 2

This sounds like a good time to use ViewBag.

The idea is that during OnActionExecuting, you would look up the subdomain and shove it into the ViewBag. This can be done in a custom BaseController from which your other controllers inherit, or from an ActionFilter.

Then, in your _ViewStart, you can write a switch statement on ViewBag to control layout.

For example, here is an ActionFilter that will populate @ViewBag.Subdomain in any of your Razor views, including _ViewStart.cshtml.

public class AddSubdomainToViewDataAttribute : ActionFilterAttribute
{
    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
        var subdomain = filterContext.HttpContext.Request.Url.Authority.Split('.').First();
        var controller = filterContext.Controller as Controller;
        controller.ViewData.Add("Subdomain", subdomain);
    }
}

Then, decorate your controllers with this new [AddSubdomainToViewData] attribute.

Finally, in _ViewStart.cshtml, do something like this:

@{
    Layout = "~/Views/Shared/" + ((@ViewContext.ViewData["Subdomain"] as String) ?? String.Empty) + "_layout.cshtml";
}

This will use a different Razor layout for each subdomain.