<?php
$m = new MongoClient();
$res = $m->demo->poiConcat->aggregate( [
[ '$match' => [ 'ts' => new MongoRegex( '/^cuisine=/' ) ] ],
[ '$unwind' => '$ts' ],
/* Match again to get rid of all the useless ts */
[ '$match' => [ 'ts' => new MongoRegex( '/^cuisine=/' ) ] ],
] );
var_dump( $res['result'] );
?>