CakePHP HABTM Form Submission - cakephp

Question

I have two tables, questions and tags, that have a HABTM relationship. When adding a question, I want to be able to specify a tag for the question (this would just be the first tag, with ability to add more tags later). The tags are pulled from their table. How can I configure my application so that when a question is added and a tag is specified, the join is reflected in the join table (questions_tags)?
Here is my question add action code :
function add() {
$tags = $this->Question->Tag->find('all');
$this->set('tags',$tags);
if (!empty($this->data)) {
$this->Question->create();
if ($this->Question->save($this->data)) {
$this->Session->setFlash(__('The question has been saved', true));
$this->redirect(array('action' => 'index'));
} else {
$this->Session->setFlash(__('The question could not be saved. Please, try again.', true));
}
}
$users = $this->Question->User->find('list');
$tags = $this->Question->Tag->find('list');
$this->set(compact('users', 'tags'));
}
and here is my question add view code:
<?php
echo $this->Form->create('Question');
echo $this->Form->input('user_id',array('type' => 'hidden', 'value' => $this->Session->read('Auth.User.id')));
echo $this->Form->input('title');
echo $this->Form->input('details',array('type' => 'textarea'));
echo $this->Form->input('tag_id');
echo $this->Form->end(__('Submit', true));
?>

Answer 1

First make sure that your models are set up the right way. The fact that a user initially just adds one tag to your question does not change the fact that you should have a HABTM relation between the Question model and the Tag model (because you want the possibility add more tags later).
If your $this->data array is build according to the following schema:
$this->data = array(
'Question' => array(
'name' => 'Trick question'
),
'Tag' => array(
'Tag' => array(1,2,3)
)
);
Then a $this->Question->save() will save the Question data as well as the related Tag data (in this case Question 'Trick Question' with Tags with the id 1, 2 and 3).
Maybe take one step back and bake your Models, Views and Controllers for these two models (again) and see what Cake makes out of it. If I'm correct you'll just need a $this->Form->input('Tag') somewhere in your form (and if that not fills in the right data automatically you want to fill the options parameter with the result of $this->Question->Tag->find('list')).

Answer 2

if you have a single tag for a question, it's not HABTM. it has to be one to one or one to many relation.
in your questions model you can define property belongsTo:
class Question extends AppModel {
var $name = 'Question';
var $belongsTo = array(
'Tag' => array(
'className' => 'Tag',
'foreignKey' => 'tag_id'
)
);
}
Something like this.
here is a link describing how to set HABTM
HABTM