Change de fetch mode

I need change de fetch mode with PDO::FETCH_OBJ.
I see that for change is in the Connection.php in the line 49.
```php
    /**
     * The default fetch mode of the connection.
     *
     * @var int
     */
    protected $fetchMode = PDO::FETCH_ASSOC;
```
Can change in another place with a public function?