(Please note: This is as much a study in behaviors use as it is an efficient means of accomplishing the objective. There are many ways in CakePHP to accomplish the same thing, but this is the way I've decided to go with this project.)
Consider this:

I have many types of 'collections' in my app. For example, 'Books' are collections of 'Stories' and 'Albums' are collections of 'Photos'.

All of my collections have some things in common:

1. They all have associations and required methods that are unique to them, justifying each having their own Model.
2. They all have the same table structure.
3. Most importantly, they all have Posts that belongTo them.

I've seen many methods to handle the Posts table and how it associates back to collections. Usually there is a condition test that checks on the value of a 'type' field and manipulates the data, setting the value on saves or passing an expected value condition on finds. This is often done in a controller, and often done in more than one place when recursion is involved.

Because of the similarities of my collections, I've decided to use the same table for all of them, and put the 'type' field within that table. This allows me to have many Models(point 1) share the same table(point 2), and the behavior allows the simplification of conditions in all CRUD actions by moving it out of the Post Model and all controllers and into the different collection models(point 3).

To help clarify, here is the SQL to define the tables:


CREATE TABLE `collections` (
  `id` INT(10) unsigned NOT NULL AUTO_INCREMENT,
  `created` DATETIME DEFAULT NULL,
  `modified` DATETIME DEFAULT NULL,
  `name` VARCHAR(100) DEFAULT NULL,
  `type` VARCHAR(20) DEFAULT NULL,
  PRIMARY KEY  (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

CREATE TABLE `posts` (
  `id` INT(10) unsigned NOT NULL AUTO_INCREMENT,
  `created` DATETIME DEFAULT NULL,
  `modified` DATETIME DEFAULT NULL,
  `collection_id` INT(10) unsigned NOT NULL DEFAULT '1',
  `label` VARCHAR(100) DEFAULT NULL,
  `body` VARCHAR(100) DEFAULT NULL,
  PRIMARY KEY  (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

I don't need a Collection Model, since I will never need to refer to it that way. Instead, I create each of the models that use the table seperately.

Model Class:

<?php 
class Book extends AppModel {
    var $name = 'Book';

    var $useTable = 'collections';
    var $actsAs = array('Collection');

    var $hasMany = array('Post');
}
?>
and one Model for Posts, with the necessary associations.

Model Class:

<?php 
class Post extends AppModel {
    var $name = 'Post';

    var $belongsTo = array('Book' => array(
        'foreignKey' => 'collection_id'));
}
?> The magic is done here with the addition of $actsAs in the Book Model.


<?php
class CollectionBehavior extends ModelBehavior {

    function setup(&$model, $config = array()) {
        if (empty($config)) {
            // if no value set, then use the default 'type'=>'ModelName'
            $this->settings[$model->name] = array('type' => $model->name);
        } else {
            // assign the settings for this Model
            $this->settings[$model->name] = $config;
        }
    }

    // we want to only get results with a fixed condition
    function beforeFind(&$model, &$query) {
        $query['conditions'] = am($query['conditions'], $this->settings[$model->name]);
    }

    // we force the values we want
    function beforeSave(&$model) {
        foreach ($this->settings[$model->name] as $field=>$value) {
            $model->data[$model->name][$field] = $value;
        }
    }
}
?>

[Saving to keep from timing out my session]