Resource already exist

common.php

function aliasExists($pageId, $parent = null){
    $modx = modX::getInstance();
    $c = $modx->newQuery('modResource');
    $c->where(array('alias' => $pageId));

    if ($parent) {
        $c->andCondition(array('parent' => $parent));
    }

    $count = $modx->getCount('modResource', $c);
	if ($count){
		return true;
	}
	return false;
}