How Can I Gather Data Based On An Undetermined # Of Parameters?

I have a model, and that model has a few items in it, eg:

$name; //A text field
$type; //A dropdown with a few options
$data;

I'd like to dynamically show content once a user selects a type, then return that content as an array to $data - and ultimately create the item. *Note* The types aren't identical in the parameters they contain, eg type 'text' might require length, and text, while 'number' might require default, min and max.

I wasn't entirely sure how to go about this so I've created a model for each type, and use a dropdown to render that types options, eg:

<?php  
$form->dropdownListRow($model, 'type', array_merge(array(''=>'---'),ProfileFieldRule::itemAlias('type')) ,
                array('class' => 'span5', 'maxlength' => 45, 
                    'ajax'=>array(
                        'type'=>'POST',
                        'url'=>CController::createUrl('ProfileFieldRule/showAttributes'),
                        'update'=>'#showAttributes',
                        ))));
?>
<div id="showAttributes"></div>

The actionShowAttributes method simply loads the correct model based on type and calls render partial on a view: '_attributes' which then displays each attribute related to the type.

$this->renderPartial('_attributes', $data, false, true);

I'm now stuck. How do I go about turning the data into an array, and sending it back to $rule variable? When I submit the form, the only $_POST data that is submitted appears to be that of the original model used to create the form.


Alternately, is there a better way of accomplishing this?

Thanks in advance!