如何使用mongodb数据库连接laravel中的3个表？

'mongodb' => [
    'driver'   => 'mongodb',
    'host'     => env('DB_HOST', 'localhost'),
    'port'     => env('DB_PORT', 27017),
    'database' => env('DB_DATABASE', 'database'),
    'username' => env('DB_USERNAME', 'username'),
    'password' => env('DB_PASSWORD', 'password'),
    'options'  => [
        'database' => env('DB_AUTHENTICATION_DATABASE', 'admin'),
    ],
],

namespace App;

use Jenssegers\Mongodb\Eloquent\Model;

class User extends Model
{
    protected $connection = 'mongodb';
    protected $collection = 'users';
}

class Post extends Model
{
    protected $connection = 'mongodb';
    protected $collection = 'posts';
}

class Comment extends Model
{
    protected $connection = 'mongodb';
    protected $collection = 'comments';
}

$user = User::find($userId);
$posts = Post::where('user_id', $user->id)->get();

foreach ($posts as $post) {
    $comments = Comment::where('post_id', $post->id)->get();
    // 处理评论数据
}