在选项查询mongo中向函数php添加参数？

My mongoDB have field: $creatime, I want add field to function php. How do it?

$ops = array(
  array('$match' => $query),
  array('$addFields' => array('date_code' => functionPHP('$create_time'))),
);

$results = $col->aggregate($ops,array('cursor' => array('batchSize' => 200)));