PHP7使用mongo扩展写aggregate

<?php
$manager = new MongoDB\Driver\Manager('mongodb://localhost:27017');
$command = new MongoDB\Driver\Command([
    'aggregate' => '表名',
    'pipeline' => [
        ['$match' => ['isDeleted' => false]],
        ['$group' => ['_id' => '$phone', 'sum' => ['$sum' => 1]]],
    ],
    'cursor' => new stdClass,
]);
$cursor = $manager->executeCommand('数据库名字', $command);

foreach ($cursor as $key => $document) {
    var_dump($document);
}