{
"_id" : ObjectId("569ec058b8c96e09421b29f4"),
"clinked_by" : [ *{* *"slug" : "derick-rethans", "name" : "Derick Rethans"* *}* ]
}
$q = [ '_id' => new ObjectID( $checkin_id ), 'clinked_by.slug' => $slug ];
$spec = [ *'$addToSet'* => [
'clinked_by' => [ 'slug' => $user->slug, 'name' => $user->fullname ]
] ];
$bw = new BulkWrite;
$bw->update( $q, $spec );
$manager->executeBulkWrite( $bw );