Sample Query String Appending

devinsays-append-query-strings.php

<?php
function devinsays_append_query_strings( $url ) {
  
  error_log('inital url');
  error_log($url);
  
  // If no cookie set, return.
  if ( ! isset( $_COOKIE['affwp_ref'] ) ) {
    return $url;
  }
  
  // Get affiliate reference, and create query string.
  $ref = $_COOKIE['affwp_ref'];
  $query = "afftrack=$ref&subid=$ref&u1=$ref&sub-id=$ref";
  
  // Modify the URL by appending the new query strings.
  $modifiedUrl = $url;
  $parsedUrl = parse_url($url);
  error_log( print_r($parsedUrl, true ));
  $separator = isset($parsedUrl['query']) ? '&' : '?';
  $modifiedUrl .= $separator . $query;
  
  error_log('modified url');
  error_log($modifiedUrl);
  
  return $modifiedUrl;
}