数组查询PHP + mongoDB - 投票系统ips

can you maybe help me please? I'm making my voting system in php + mongodb, and I would like to keep the ip addresses which already voted. What would be to best way? I was thinking about doing it like this:

$ip=$_SERVER['REMOTE_ADDR'];
$ipData = array('$push' => array('ips' => $ip), '$inc' => array('votes' => 1));
$collection->update(array( '_id' => $id), $ipData);

Is this the best way to do it? How would you than compare all the elements of the ips array to see if the ip already didn't voted? The list will look like (192.168.0.1, 127.0.0.1, 123.45.67.8).

Thank you!

compare the user's ip with the array of IPs using the PHP function in_array()

http://php.net/manual/en/function.in-array.php

Use a Unique Index and a UPSERT:

$collection->ensureIndex(array('ips'), array('unique' => true));