Applying Limit on associated model Cakephp 2.3x HABTM - php

Question

My Category Model:
class Category extends AppModel {
public $displayField = 'name';
// public $actsAs = array('Containable');
public $hasAndBelongsToMany = array(
'Post' => array(
'className' => 'Post',
'joinTable' => 'categories_postss',
'foreignKey' => 'category_id',
'associationForeignKey' => 'post_id',
'unique' => 'keepExisting'
)
);
}
$params['contain'] = array('Post' => array(
'limit'=> 3));
pr($this->Category->find('first',$params)); exit;
It is fetching all Posts, irrespective of limit.
What I want to do:
I have this page where I ma listing all the categories and latest 5 posts related to it.
I want to limit the associated model to only 5 rows.
Any ideas?

Answer 1

Containable behavior is not in use
The most likely reason for this problem is that the containable behavior is not being used at all.
Compare, for the below code example:
$results = $this->Category->find('first', array(
'contain' => array(
'Post' => array(
'limit' => 3
)
)
));
Without containable behavior, it'll generate the following queries:
SELECT ... FROM `crud`.`categories` AS `Category` WHERE 1 = 1 LIMIT
SELECT ... FROM `crud`.`posts` AS `Post`
JOIN `crud`.`categories_posts` AS `CategoriesPost` ON (...)
With containable behavior, it'll generate the following queries:
SELECT ... FROM `crud`.`categories` AS `Category` WHERE 1 = 1 LIMIT
SELECT ... FROM `crud`.`posts` AS `Post`
JOIN `crud`.`categories_posts` AS `CategoriesPost` ON (...) LIMIT 3
Given this (and the code in the question) check that the AppModel has the containable behavior in $actsAs:
<?php
// app/Model/AppModel.php
class AppModel extends Model {
public $actsAs = array('Containable');
}
Limit always required?
Alternatively, or possibly in addition, you may prefer to put a limit in the association definition - To do so just define the 'limit' key:
class Category extends AppModel {
public $hasAndBelongsToMany = array(
'Post' => array(
'limit' => 100, // default to a high but usable number of results
)
);
}

Answer 2

the hasAndBelongsToMany relationship seems unnecessary to me. I think you only need Category hasMany Post and Post belongsTo Category relationships. Add category_id to the posts table. Make both models actAs containable.
Post Model
class Post extends AppModel {
public $actsAs = array('Containable');
var $belongsTo = array(
'Category' => array(
'className' => 'Category',
'foreignKey' => 'category_id'
),
// ... more relationships
);
Category Model
class Category extends AppModel {
public $actsAs = array('Containable');
var $hasMany = array(
'Post' => array(
'className' => 'Post',
'foreignKey' => 'category_id'
),
// ... more relationships
);
Categories Controller
class CategoriesController extends AppController {
public $paginate = array(
'Category' => array(
'contain' => array(
'Post' => array(
'limit' => 3
), // end Post
) // end Category contain
) // end Category pagination
); // end pagination
public function index() {
// for paginated results
$this->set('categories', $this->paginate());
// for find results
$this->Category->contain(array(
'Post' => array(
'limit' => 3
)
));
$this->set('categories', $this->Category->find('all'));
}