title: How to get parameter in OnActionExecuting?
body: <p>I modify the default route rule a little bit as below:</p>
  
  <pre><code>routes.MapRoute(
    "Default",                                              // Route name
    "{controller}/{action}/{id}",                           // URL with parameters
    new { controller = "Home", action = "Index", id= (string)null }  // Parameter defaults
  );
  </code></pre>
  
  <p>Then I can set url as:</p>
  
  <pre><code>/Controller/Action/myParam
  /Home/Index/MyParam
  </code></pre>
  
  <p>The default Action Index would be:</p>
  
  <pre><code>public ActionResult Index(string id)
  {
    //....
  }
  </code></pre>
  
  <p>I can get the param in action. But I want to get the param in OnActionExecuting. How can I do it?</p>