Can't access values in MongoDB with cursor using PHP

I seem to 开发者_运维百科be having some trouble using the cursor as I try to pull data out of a MongoDB. Here is a screenshot of my simple data structure:

data structure screenshot http://droplr.com/IpcH+

I'm trying to use the following:

$collection_name = "users";
$collection = $this->mongo->db->$collection_name;
$which_document = array("email" => $email_address);
$which_fields = array("words");
$cursor = $collection->find($which_document, $which_fields);

But my $cursor does not seem to be going any further into the document than the actual document. In the end, I'm looking to sort() and limit() on the created_at field within the "words" field, but I seem to be at an impasse here. And either MongoDB's error passing isn't very helpful, or I've no idea how to use it properly. (I'd assume the latter.)

One idea: I'm not sure the "words" table being generated inside of square brackets is correct, but here is the code I'm using to insert data here:

function create_word($word, $email_address){
    $collection = 'users';

// make sure word isn't null
if($word !== NULL){

// add new data to the 'words' set
    $new_data = array('$addToSet' => array('words' => array(
                                                            'word' => $word,
                                                            'status' => 'open',
                                                            'created_at' => time()
                                                            )));
    $this->mongo->db->$collection->update(array('email' => $email_address), $new_data);         
}

Thanks so much for any help you can give!

You can't sort subdocuments. You need to do it on the client side. In your case retrieve the words array:

$array = iterator_to_array($cursor); 
$words = $array[0]["words"];

and then use php to sort the values.

Try

$collection->find(array($which_document, $which_fields))->sort(array("words.created_at" => -1));