Form validation with file upload

[eluser]tokyotech[/eluser]
I think I'll just do this:

Code:

// ....
$this->form_validation->set_rules(
    'thumbnail',
    'thumbnail',
    'callback_properThumbnail'
);
// ...

public function properThumbnail($dontCare)
{
    if (!isset($_FILES['thumbnail']) || $_FILES['thumbnail']['size'] <= 0) {
        $this->form_validation->set_message(
            'properThumbnail',
            'The %s is required'
        );
        return false;
    }
    else {
        return true;
    }
}