title: push new value to mongodb inner array - mongodb/php
body: <p>i have this document in mongo:</p>
  
  <pre><code>{
     "_id": ObjectId("4d0b9c7a8b012fe287547157"),
     "done_by": ["1"]
  }
  </code></pre>
  
  <p>and i want to add another value to "done_by" field, so my expected document will be::</p>
  
  <pre><code>{
     "_id": ObjectId("4d0b9c7a8b012fe287547157"),
     "done_by": ["1","2","3"]
  }
  </code></pre>
  
  <p>i try this:</p>
  
  <pre><code>$conn = new Mongo();
  $q = $conn-&gt;server-&gt;gameQueue;
  $id = new MongoId("4d0b9c7a8b012fe287547157");
  $q-&gt;update(array("_id"=&gt;$id),array('$push' =&gt; array("done_by","2")));
  </code></pre>
  
  <p>but nothing happens, anyone know how to do this? </p>