title: Netscaler expression function challenge
body: <p>Trying to check if a SAML attribute contains a role retrieved from a stringmap (the attribute contains a comma separated list of roles):</p>
  
  <p><code>HTTP.REQ.USER.ATTRIBUTE(5).CONTAINS(HTTP.REQ.URL.QUERY.VALUE("pageid").MAP_STRING("UrlProtection"))</code></p>
  
  <p>Unfortunately Netscaler complains: <code>Only constant parameters are allowed for function ["pageid").MAP_STRING, 72]</code></p>
  
  <p>Any ideas how to get around this?</p>