CakePHP saving foreignKeys not working - php

Question

I have 3 tables: Computers hasMany Brands, Brands belongsTo Computers and Parts. Now i have these fields in my Brands description,computer_id,part_id. I have the code below to save my data. It will save the description and part_id....But my computer_id does not save at all.
Usually my URL written http://192.168.6.253/computers/brands/add/1 where 1 is computer_id.
How will I save it? Im still beginner in this framework
Controller
public function add($id = null) {
if (!$id) {
throw new NotFoundException(__('Invalid post'));
}
//Assign value to link computer_id
$data = $this->Brand->Computer->findById($id);
$this->set('computers', $data);
//assign select values to parts select
$this->set('parts', $this->Brand->Part->find('list',
array('fields' => array('description'))));
if ($this->request->is('post')) {
$this->Brand->create();
if ($this->Brand->save($this->request->data)) {
$this->Session->setFlash(__('Your post has been saved.'));
$this->redirect(array('action' => 'table/'.$id));
} else {
$this->Session->setFlash(__('Unable to add your post.'));
}
}
}
View
<?php
echo $this->Form->create('Brand');
echo $this->Form->input('part_id',array('empty'=>' '));
echo $this->Form->input('description');
echo $this->Form->input('computer_id',array('type'=>hidden));
echo $this->Form->end('Save Post');
?>

Answer 1

If you are not requiring to send the computer id through the form since it's a url param... you can adjust your add function like this
if ($this->request->is('post')) {
$this->request->data['Brand']['computer_id'] = $id; //manually add the id to the request data object
$this->Brand->create();
if ($this->Brand->save($this->request->data)) {
$this->Session->setFlash(__('Your post has been saved.'));
$this->redirect(array('action' => 'table/'.$id));
} else {
$this->Session->setFlash(__('Unable to add your post.'));
}
}
That's a very basic way of doing it without checking for data integrity, anyone could easily change the param to a 2, but it conforms with your current setup.