<?php
$m = new MongoClient();
$c = $m->demo->cities;
$res = $c->aggregate( [
[ '$match' => [ 'name' => 'Atlanta' ] ],
[ '$unwind' => '$alternatenames' ],
[ '$project' => [
'name' => '$alternatenames',
'meta' => [
'elevation' => '$dem',
'population' => 1,
'timezone' => 1,
],
'location' => 1,
'_id' => 0,
] ],
[ '$sort' => [ 'name' => 1 ] ]
] );
var_dump( $res );
?>