Commenting system for CakePHP blog tutorial - cakephp

Question

I'm building off the CakePHP tutorial for the blog engine by adding comments to each post. I am able to add comments by selecting the post that it should be attached to, via a select box. I would like to be able to click an "Add Comment" link within the post and have the association to the post formed programatically. I am unsure how I can pass the post_id to the add method within my comments_controller. The body of my add method is the auto-generated scaffold code. Is it as easy as adding a $postId argument to the add method and write this to the post_id in my comments model? This doesn't feel right though, since I would expect add to be called when my submit button is click on my comments add view.
Thanks all.
EDIT - Added the code that I'm working with currently. It is just the add method in my comments_controller.
function add($postid = null) {
if(!empty($this->data) {
$this->Comment->create();
$this->Comment->post_id = $postid;
if ($this->Comment->save($this->data)) {
$this->Session->setFlash(__('The Comment has been saved', true));
$this->redirect(array('action' => 'index'));
} else {
$this->Session->setFlash(__('The Comment could not be saved. Please,
try again.', true));
}
}
$this->set('post_id', $postid);
print_r($postid);
}

Answer 1

function add($postid = null) {
if(!empty($this->data) {
$this->Comment->create();
$this->data['Comment']['post_id'] = $postid; // see how it needs to be?
...then save the data...

Answer 2

Create your link at the bottom of your blog post as,
<?php echo $html->link('Add Comment', array('controller'=>'Comments','action'=>'add',$post->id)) ?>
Then you can, in your Comments controller's Add method,
function add($postid){
$this->data->Comment->post_id = $postid;
$this->data->Save();
}
Similar to this would do you just fine I'd say. Then your url would be example.com/comments/add/3 Double check the code though, as it's first thing in the morning and we've run out of milk, so I have had no coffee! ;)