CakePhp adding a comment to Photo
===

I have a problem with adding comments to photos on my website. In camments table I have:
id user_id photo_id content created modified erased

In view I create:

    echo $this->Form->create('Comment');
    echo $this->Form->input('title');
    echo $this->Form->input('content');
    echo $this->Form->input($this->Session->read('User.id'), array('type'=>'hidden'));
    echo $this->Form->input($photo['Photo']['id'], array('type'=>'hidden'));
    echo $this->Form->end('Add comment');

I don't know if it is correct way. How cake will now that 2 hidden values are user_id and photo_id ? 

Thx for advices.