Sort by TV without getResources? possible?

$criteria = $modx->newQuery('modResource');
$criteria->where(array(
           'published' => 1,
           'deleted'=> 0,
           'template'=> 5
           ));
$criteria->sortby('MyDateTv','ASC');

$agendaBlocks  = $modx->getCollection('modResource',$criteria);

    function sortTV($sort, &$c, $dir = 'ASC', $sortbyTVType = '')
    {
        $c->leftJoin('modTemplateVar', 'tvDefault', array("tvDefault.name" => $sort));
        $c->leftJoin('modTemplateVarResource', 'tvSort', array("tvSort.contentid = modResource.id", "tvSort.tmplvarid = tvDefault.id"));
        if (empty($sortbyTVType)) $sortbyTVType = 'string';
        if ($this->modx->getOption('dbtype') === 'mysql') {
            switch ($sortbyTVType) {
                case 'integer':
                    $c->select("CAST(IFNULL(tvSort.value, tvDefault.default_text) AS SIGNED INTEGER) AS sortTV");
                    break;
                case 'decimal':
                    $c->select("CAST(IFNULL(tvSort.value, tvDefault.default_text) AS DECIMAL) AS sortTV");
                    break;
                case 'datetime':
                    $c->select("CAST(IFNULL(tvSort.value, tvDefault.default_text) AS DATETIME) AS sortTV");
                    break;
                case 'string':
                default:
                    $c->select("IFNULL(tvSort.value, tvDefault.default_text) AS sortTV");
                    break;
            }
        }
        $c->sortby("sortTV", $dir);

        return true;
    }

sortTV('MyDateTv', $criteria);