raw code for handling Google Analytics clientId in a separate secure https cookie and writing it to the dataLayer to be used by ga tracking tags

secure_ga_cookie.php

<?php
  //optional: set this to desired cookie domain. example ".mydomain.de" to cover all subdomains  
  $domain = "";
  //get client id from secure http cookie
  $cid = ($_COOKIE['_hga']); 
  //new user? get _ga cookie client id, if exists
  if (!isset($cid)) $cid = ($_COOKIE['_ga']); 
  //still no id? create new cliend id
  if (!isset($cid)) $cid = rand(10000, 99999).rand(20000, 99999).".".time(); 
  //Set secure http cookie with 2 years lifetime
  setcookie("_hga", $cid, time()+60*60*24*365*2, 
            "/; samesite=strict'", $domain, 
            $secure = true, $httponly = true);
  //write script to push client id to dataLayer 
  echo "<script>\n".
  "window.dataLayer = window.dataLayer || [];\n".
  "window.dataLayer.push({\n".
  "'event': 'clientIdReady',\n".
  "'secureClientId': '".$cid."'\n".
  "});\n".
  "</script>";
  //optional: set global js variable for direct implementations of ga code
  //echo "<script>window._secureClientId='".$cid."';</script>";
?>

Hi @mbaersch

Thanks for this solution. How would it work on subdomains which are not part of the same solution as the top domain? The datalayer will be lost when the user navigates from top domain to one of the subdomains which are not part of the topdomain code/solution.

Any solution for that?

Hello @awaismun, just enter your domain starting with a dot to cover all hosts. See comment in the very first line 😉