如何在PHP中选择MongoDate？

Question

如何选择MongoDate？我有这样的代码：

<?php
$conn = new Mongo();
$db = $conn->selectDB('jam');

$dt = new DateTime(date('Y-m-d'), new DateTimeZone('UTC'));
$ts = $dt->getTimestamp();
$today = new MongoDate($ts);

$query = $db->test;
$query->insert(array("today"=>$today));
?>

这是插入MongoDate的代码，但我无法捕捉格式（'Y-m-d'）。这是我选择的代码：

<?php
$conn = new Mongo();
$db = $conn->selectDB('jam');

$dt = new DateTime(date('Y-m-d'), new DateTimeZone('UTC'));
$ts = $dt->getTimestamp();
$today = new MongoDate($ts);

$query = $db->tes;
$cursor = $query->find();
foreach($cursor as $id=>$b){
        echo "<h2><a href='formlist2.php?id=".$id."'>".$b['today']."</h2>";
        }
?>

但结果是：

0.00000000 1484352000
0.00000000 1484352000
0.00000000 1484352000