Using CakePHP all your form fields are normally populated automatically, it is easy to forget that to access the POST array all you need to do is use either:
$this->data or $this->params[‘data’]
pr(); on either of these will present you with something like:
Array ( [Book] => Array ( [id] => 402 [name] => Everything about Everything [publisher] => [ISBN] => [publish_date] => 15/04/2001 [summary] => ) )