Creating 'select' listboxes using FormHelper in CakePHP - cakephp

Question

I have two models, Category and Point. The associations are defined as:
Category hasMany Point
Point belongsTo Category
I would like, when adding Points to my database, to be able to select the category it belongs to from a <select> box, along with the rest of the form data.
Where would I need to set the category list and how could I do it? And how would I produce the select box?
I assume it could be done with
$form->input('categorieslist',array('type'=>'select')); //categorieslist needs
//setting somewhere.

Answer 1

Also to generalize a bit:
In a View with access to the Form helper
<?php
echo $form->input( 'dataKey', array(
'type' => 'select',
'options' => array(
'key1' => 'val1',
'key2' => 'val2',
),
));
?>
The above will render a select input with two options. You can also place an empty option as the first item. Passing a value of true will simply append an empty option with a blank value to the beginning of the options rendered in the HTML.
<?php
echo $form->input( 'dataKey', array(
'type' => 'select',
'options' => array(
'key1' => 'val1',
'key2' => 'val2',
),
'empty' => true,
));
?>
You can pass a string to the 'empty' key to have it display custom text as the key field for the empty option.
<?php
echo $form->input( 'dataKey', array(
'type' => 'select',
'options' => array(
'California' => 'CA',
'Oregon' => 'OR',
),
'empty' => 'choose a state',
));
?>
One last example, you can also pre-select an option with the selected key. The value should match the value of one of the select options, not the key.
<?php
echo $form->input( 'dataKey', array(
'type' => 'select',
'options' => array(
'California' => 'CA',
'Oregon' => 'OR',
),
'empty' => 'choose a state',
'selected' => 'California',
));
?>
From the Model
Model->find( 'list', array( ... )); will always return an array formatted for use with select box options. If you pass data to your view stored in a variable with a lowercase plural model name, that is, ( $this->set( 'categories', $categories );, then you will automagically generate drop downs for related models by using the form helper in the view and passing it a data index of the same model name in singular form suffixed with "_id".
Aziz's answer at #2 is the example of that automagic kicking in.
CakePHP 1.3 Form Helper
CakePHP1.2 Form Helper

Answer 2

In the controller:
$categories = $this->Point->Category->find('list');
$this->set(compact('categories'));
In the view:
$form->input('category_id',array('type'=>'select'));