从PHP中的聚合mongodb获取数据

Question

**I have a database in MongoDB
if I use CMD using the aggrate script the results will appear**

result like this using cmd

db.getCollection('teacher').aggregate( [ {$group : {_id: '$name', count : {$sum : 1}}} ])
{ "_id" : "budi", "count" : 3 }
{ "_id" : "sinta", "count" : 3 }

如果PHP的强制执行与使用CMD导致的结果不同

这是PHP中的代码

**

$cmd = new \MongoDB\Driver\Command([
            'aggregate' => 'collection',
            'pipeline' => [['$group' => ['_id' => '$name', 'count' => ['$sum' => 1]]]],
            'cursor' => new stdClass,
            ]); 
        $cursor = $manager->executeCommand('teacher', $cmd);
        $records = iterator_to_array($cursor,true);
        var_dump($records);
        echo '<pre>';
        echo print_r($records);
        echo '</pre>';

**

从头开始

**array(0) { }
Array
(
)**

please help me to generate data like in CMD using PHP