/**
  * Checks $_POST and $_SESSION for search terms or if user has clicked the 'clear' button
  * @return string
  */
 private function get_search_term()
 {
     if (get_Post("{$this->filter_post_var}_clear")) {
         $_SESSION[$this->filter_post_var] = '';
         $return = '';
     } elseif ($s = get_Post($this->filter_post_var)) {
         $_SESSION[$this->filter_post_var] = $s;
         $return = $s;
     } elseif (!empty($_SESSION[$this->filter_post_var])) {
         $return = $_SESSION[$this->filter_post_var];
     } else {
         $return = '';
     }
     return $return;
 }
 /**
  * Loads any data from $_POST
  */
 private function load_posted_data()
 {
     foreach ($this->fields as $f) {
         if ($val = get_Post($f->get_post_var_name())) {
             $f->set_posted_value($val);
             $f->set_value($val);
         }
     }
 }