How to capture values from referrer?

Carl,

I'm trying out the function you posted above and for some reason it's returning blank. Below is my code:

<cfhttp url="https://app.knowledgeowl.com/api/head/article.json" method="get" timeout="15">

  <cfhttpparam type="url" name="_authbykey" value="56a7d8c123131c4058361789">

    <cfhttpparam type="url" name="project_id" value="55c4ffd456131c527e7899fe6">

    <!---<cfhttpparam type="url" name="url_hash" value="calendar">--->

     <!--- Pass along any URL values. --->

     <cfhttpparam type="url" name="url_hash" value="#queryStringGetVar(CGI.http_referer, 'slug')#" />

     <cflog text="URL-Hash: #queryStringGetVar(CGI.http_referer, 'slug')#" type="Information" file="CGIparameters">

</cfhttp>

<cfscript>

  /**

* Gets the value of a variable in a query string.

*

* @param query_string The query string to examine. (Required)

* @param this_var_name The variable to look for. (Required)

* @return Returns a string.

* @author Shawn Seley (shawnse@hotmail.com)

* @version 1, August 1, 2005

*/

  function queryStringGetVar(querystring, this_var_name){

  var re_found_struct = "";

  querystring = trim(querystring);

  re_found_struct = REFindNoCase("(^|[\?|&])#this_var_name#=([^\&]*)", querystring, 1, "true");

  // = re_found_struct.len & re_found_struct.pos

  if(arrayLen(re_found_struct.pos) gte 3) {

  if (re_found_struct.pos[3] GT 0) return urlDecode(mid(querystring, re_found_struct.pos[3], re_found_struct.len[3]));

  else return "";

  } else return "";

  }

</cfscript>

The log shows blank. So, I'm not quite sure why. The CGI.http_referrer shows this: https://devbox.mysite.com/kb/?slug=calendar