/**
  * getFilename
  */
 public function getFilenameToSave($file_name, $survey_entry_id, $question_id, $answer_id)
 {
     if (!$file_name) {
         return false;
     }
     if (!is_numeric($survey_entry_id)) {
         return false;
     }
     if (!is_numeric($question_id)) {
         return false;
     }
     if (!is_numeric($answer_id)) {
         return false;
     }
     require_once 'models/common/common_file.php';
     $file_name = common_file::nameToSafe($file_name);
     $file_name = "{$survey_entry_id}-{$question_id}-{$answer_id}-" . $file_name;
     return $file_name;
 }