title: How do I use VaryByParam with multiple parameters?
body: <p>In ASP.NET MVC2 I use <code>OutputCache</code> and the <code>VaryByParam</code> attribute. I got it working fine with a single parameter, but what is the correct syntax when I have several parameters on the method?</p>
  
  <pre class="lang-cs prettyprint-override"><code>[OutputCache(Duration=30, VaryByParam = "customerId"]
  public ActionResult Index(int customerId)
  {
  //I've got this one under control, since it only has one parameter
  }
  
  [OutputCache(Duration=30, VaryByParam = "customerId"]
  public ActionResult Index(int customerId, int languageId)
  {
  //What is the correct syntax for VaryByParam now that I have a second parameter?
  }
  </code></pre>
  
  <p>How do I get it to cache the pages using both parameters? Do I enter add the attribute twice? Or write "customerId, languageId" as the value??</p>