title: How to create a filter that returns a forbidden result
body: <p>I want to create a web api filter that checks if the request header has the correct Api key.</p>
  
  <p>If it doesn't, I want to return 403 response code and halt execution (forbidden action)</p>
  
  <pre><code>public class ApiPermission : ActionFilterAttribute
  {
          public override void OnActionExecuting(ActionExecutingContext filterContext)
          {
  
          }
  }
  </code></pre>
  
  <p>Using the filterContext I know I can do something like:</p>
  
  <pre><code>filterContext.Result = new RedirectTo...
  </code></pre>
  
  <p><strong>But how can I change the status code to 403 and just return a string and halt execution and stop processing other filters and the controller action?</strong></p>