CakePHP - Sorting using HABTM Join Table Field

Question

Hello Cake Gurus, here's my problem:

Table1: Posts

id - int
title - varchar

Table2: Categories

id - int
name - varchar

HABTM JoinTable: categories_posts

id - int
post_id - int
category_id - int
postorder - int

As you can see, the join table contains a field called 'postorder' - This is for ordering the posts in a particular category. For example,

Posts: Post1, Post2, Post3, Post4
Categories: Cat1, Cat2
Ordering:
     Cat1 - Post1, Post3, Post2
     Cat2 - Post3, Post1, Post4

Now in CakePHP,

$postpages = $this->Post->Category->find('all');

gives me a array like

Array
(
  [0] => Array
    (
      [Category] => Array
        (
          [id] => 13
          [name] => Cat1
        )
        [Post] => Array
        (
          [0] => Array
          (
            [id] => 1
            [title] => Post2
            [CategoriesPost] => Array
            (
              [id] => 17
              [post_id] => 1
              [category_id] => 13
              [postorder] => 3
            )
          )
          [1] => Array
          (
            [id] => 4
            [title] => Post1
            [CategoriesPost] => Array
            (
              [id] => 21
              [post_id] => 4
              [category_id] => 13
              [postorder] => 1
            )
          )

        )
    )
) 

As you can see [Post], they are not ordered according to [CategoriesPost].postorder but are ordered according to [CategoriesPost].id. How can I get the array ordered according to [CategoriesPost].postorder?

Thanks in advance for your time :)

Update 1: The Queries from Cake's SQL Log are:

SELECT `Category`.`id`, `Category`.`name` FROM `categories` AS `Category` WHERE 1 = 1

SELECT `Post`.`id`, `Post`.`title`, `CategoriesPost`.`id`, `CategoriesPost`.`post_id`, `CategoriesPost`.`category_id`, `CategoriesPost`.`postorder` FROM `posts` AS `Post` JOIN `categories_posts` AS `CategoriesPost` ON (`CategoriesPost`.`category_id` IN (13, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52) AND `CategoriesPost`.`post_id` = `Post`.`id`) 

What I am looking for is how to make cake put a Order By CategoriesPost.postorder in that second SELECT SQL Query.

Update 2: Trying to use order as following

$this->Post->Category->find('all',array('order'=>array('postorder'=>'ASC')));

throws an SQL error

SQL Error: 1054: Unknown column 'PostsCategory.postorder' in 'order clause'

The SQL Query is

SELECT `Category`.`id`, `Category`.`name` FROM `categories` AS `Category` WHERE 1 = 1 ORDER BY `CategoriesPost`.`postorder` ASC

Instead of an ORDERBY in the second SQL query (in my update1), its getting executed in the first SQL query as shown above.

Answer 1

Try to make it part of the association:

var $hasAndBelongsToMany = array(
    'Post' => array(
        ...
        'order' => 'CategoriesPost.postorder DESC',
    )
)

This may or may not work, haven't tested it.