/**
  * This function is used to get all the attachment ids from the submissions
  * 
  * @param int $form_id
  * @return boolean
  */
 public function get_all_form_attachments($form_id)
 {
     $attachments = RM_DBManager::get_all_form_attachments($form_id);
     if ($attachments) {
         $all_attachments = array();
         foreach ($attachments as $key => $attachment) {
             $attachment = maybe_unserialize($attachment);
             if (is_array($attachment)) {
                 foreach ($attachment as $att) {
                     if (wp_get_attachment_url($att)) {
                         $all_attachments[] = $att;
                     }
                 }
             }
         }
     } else {
         return false;
     }
     return $all_attachments;
 }