/**
  * Get extra user data by field variable
  * @param string    field variable
  * @return array    data
  */
 public static function get_extra_user_data_by_field_variable($field_variable)
 {
     $extra_information_by_variable = self::get_extra_field_information_by_name($field_variable);
     $field_id = intval($extra_information_by_variable['id']);
     $extraField = new ExtraFieldValue('user');
     $data = $extraField->getValuesByFieldId($field_id);
     if (!empty($data) > 0) {
         foreach ($data as $row) {
             $user_id = $row['item_id'];
             $data[$user_id] = $row;
         }
     }
     return $data;
 }