public function checkFallback($varValue, DataContainer $dc)
{
if ($varValue == '') {
return '';
}
$objPage = $this->Database->prepare("SELECT id FROM tl_page WHERE type='root' AND fallback=1 AND dns=? AND id!=?")->execute($dc->activeRecord->dns, $dc->activeRecord->id);
if ($objPage->numRows) {
throw new Exception($GLOBALS['TL_LANG']['ERR']['multipleFallback']);
}
return $varValue;
}