How to change theme in ASP.Net MVC 5 based on querystring value?

Question

I want to change MVC theme dynamically based on querystring parameter in the url.

Eg:

1. localhost/WBE/Search/1
2. localhost/WBE/Search/2
3. localhost/WBE/Search/3

Here 1,2,3 are my customer keys and i have several customers who needs different themes in my websites. So, how can i change the layout in my website based on this key.

Awaiting for your reply.

Regards, Mallikharjun.

Answer 1

I think you could set the layout dynamically in your controller action

public ActionResult Search(int customer)
{
  string layout = ... // function which get layout name with your customer id

  var viewModel = ... // function which get model

  return View("Search", layout, viewModel);
}

Edit :

I think if you want a better solution to change the layout in all view you must create an ActionAttributeFilter which will intercept the result and inject the layout in the viewresult

Your filter :

public class LayoutChooserAttribute : ActionFilterAttribute
{
    private string _userLayoutSessionKey = "UserLayout";


    public override void OnActionExecuted(ActionExecutedContext filterContext)
    {
        base.OnActionExecuted(filterContext);


        var result = filterContext.Result as ViewResult;
        // Only if it's a ViewResult
        if (result != null)
        {
            result.MasterName = GetUserLayout(filterContext);
        }
    }

    private string GetUserLayout(ActionExecutedContext filterContext)
    {
        if (filterContext.HttpContext.Session[_userLayoutSessionKey] == null)
        {
            // I stock in session to avoid having to start processing every view
            filterContext.HttpContext.Session[_userLayoutSessionKey] = ...; // process which search the layout
        }
        return (string)filterContext.HttpContext.Session[_userLayoutSessionKey];
    }

}

Your action become :

[LayoutChooser]
public ActionResult Search(int customer)
{
  var viewModel = ... // function which get model

  return View("Search", viewModel);
}

If you want that the attribute is present in all actions, in FilterConfig.RegisterGlobalFilters static method you can add your filter :

public class FilterConfig
{
    public static void RegisterGlobalFilters(GlobalFilterCollection filters)
    {
        ...
        filters.Add(new LayoutChooserAttribute());
    }
}