/**
  * Override function to add hidden attribute to store linked sample id
  * When adding a survey 1 record this is given the value 0
  * When adding a survey 2 record this is given the sample_id of the corresponding survey 1 record.
  * @param type $args
  * @param type $auth
  * @param type $attributes
  * @return string The hidden inputs that are added to the start of the form
  */
 protected static function getFirstTabAdditionalContent($args, $auth, &$attributes)
 {
     $r = parent::getFirstTabAdditionalContent($args, $auth, $attributes);
     $linkAttr = 'smpAttr:' . $args['survey_1_attr'];
     if (array_key_exists('new', $_GET)) {
         if (array_key_exists('sample_id', $_GET)) {
             // Adding a survey 2 record
             $r .= '<input id="' . $linkAttr . '" type="hidden" name="' . $linkAttr . '" value="' . $_GET['sample_id'] . '"/>' . PHP_EOL;
         } else {
             // Adding a survey 1 record
             $r .= '<input id="' . $linkAttr . '" type="hidden" name="' . $linkAttr . '" value="0"/>' . PHP_EOL;
         }
     }
     return $r;
 }