title: Changing ActionExecutingContext values in Custom Filter Attribute
body: <p>I have a custom filter attribute that I want to use on certain ActionResults to look at the data being attempted and to set values where certain rules are violated.</p>
  
  <p>So;</p>
  
  <pre><code>public class SpecialActionFilter : ActionFilterAttribute
  {
      public override void OnActionExecuting(ActionExecutingContext filterContext)
      {
          foreach (string value in filterContext.Controller.ValueProvider.Keys)
          {
              string h = filterContext.Controller.ValueProvider[value].AttemptedValue;
  
              if (h == "1")
              {
                  //set the value of the key to be say "one".    
              }
          }
  
          base.OnActionExecuting(filterContext);
      }
  
  }
  </code></pre>
  
  <p>is this possible?</p>