Question

How would I call the id by itself?

Array
(
    [0] => Array
        (
            [_id] => MongoId Object
                (
                    [$id] => 4f98930cb1445d0a7d000001
                )
        )

)

I thought it would be:

echo $userInfo[0]['_id']->['$id'];

Answer 1

As _id is a MongoId object, you should access it’s public members like this:

echo $userInfo[0]['_id']->id;

EDIT:
The MongoId $id field starts with a dollar sign so you may have to call it by {‘$id’}, else PHP won’t parse it correctly. (thanks @cKendrick)

echo $userInfo[0]['_id']->{'$id'};