/**
  * Return the categories of the campaigns that were donated to.
  *
  * @return  string
  * @access  public
  * @since   1.4.2
  */
 public function get_campaign_categories_for_donation($value)
 {
     if (!$this->has_valid_donation()) {
         return $value;
     }
     $categories = $this->donation->get_campaign_categories_donated_to('campaign_category', array('fields' => 'names'));
     return implode(', ', $categories);
 }