Question

I’m starting a cakephp app, I’ve never used it in real world so I’m a bit confused how HABTM works, even though I read the documentation I couldn’t get even the $this->User->Subscription and didn’t see any extra object dumped

What I want is to create a HATBM between users and subscriptions

so I created three tables (users,subscriptions,users_subscribers)

Then in my User.php model I did this

var $hasAndBelongsToMany =
    array(
        'Subscription' =>
            array('className'=>'Subscription',
                'joinTable' => 'users_subscribers',
                'foreignKey'             => 'user_id',
               'associationForeignKey'  => 'subscription_id',
                'unique' => true,
               )
        );

SUbscription.php

    var $hasAndBelongsToMany = array(
        'User'=>array('className'=>'User',
                    'joinTable' => 'users_subscribers',
        'foreignKey' => 'subscription_id',
        'associationForeignKey' => 'user_id',
        'unique' => true));

Even with the tags example and following it, I cannot get the relation set, I also added the line <?php echo $this->element('sql_dump'); ?> to see if its running which it isn’t…

Could anyone guide me how exactly you get HATBM to work, what else do I need to verify?

Full code:
pages_controller.php
http://sao.pastebin.com/PWQMhE2z

User model:
http://sao.pastebin.com/PWqwAj1v

Subscription model:
http://sao.pastebin.com/MfVFR4Kw

subscriptions SCHEMA:
http://sao.pastebin.com/mLRcEp1c

User SCHEMA:
http://sao.pastebin.com/UeTRHh3u

users_subscriptions SCHEMA:
http://sao.pastebin.com/4UeSDZte

Answer 1

The simplest and fastest way to get this working is by following CakePHP’s rule of configuration over customization.

This means following the CakePHP conventions unless you have a very good reason not to.

I’d strongly recommend starting with a basic setup that you know works, and then modifying that if you need to. Here’s a quick and easy way to get up and running.

The Database Tables

Start with three database tables: users, subscriptions and subscriptions_users. The schemas you already have are ok, but I’d make a couple modifications to make sure things go smoothly:

1. Add a name or title column to the users table. Either that, or you’ll have to add the $displayField property to your User model. If you don’t do this you’ll miss out on some of the “automagic” that CakePHP provides. More info on $displayField
2. Change the join table’s name to subscriptions_users. This is the CakePHP convention and there’s no reason not to save yourself the time and worry of following it. 🙂
3. Use the following schema for the join table:
   

   CREATE TABLE subscriptions_users (
   subscription_id int(11) NOT NULL,
   user_id int(11) NOT NULL
   ) ENGINE=MyISAM DEFAULT CHARSET=utf8;
   

Note that there aren’t any keys defined. From the CakePHP manual: “To avoid any issues – don’t define a combined primary key for these two fields, if your application requires it you can define a unique index.”

The Models

Try to keep your code clean. There are a lot of sensible defaults implemented in CakePHP and there’s no point in defining them when they’re already defined.

The following models should work for you:

user.php

<?php
class User extends AppModel {
    var $hasAndBelongsToMany = array('Subscription');
}
?>

subscription.php

<?php
class User extends AppModel {
    var $hasAndBelongsToMany = array('User');
}
?>

Pretty simple. Just be sure your model files are named correctly: user.php and subscription.php, all lowercase.

Also, note that you don’t have to set any of the relationship options (className, joinTable, etc.) unless they need to be something besides the default. Ninety percent of the time the defaults should serve you just fine.

You should be up and running now. You can make sure the model objects are being loaded and are accessible in your controllers like this:

users_controller.php

<?php
class UsersController extends AppController {
    var $name = 'Users';

    function index() {
        $this->autoRender = false;
        var_dump(is_object($this->User));
        var_dump(is_object($this->User->Subscription));
    }
}
?>

subscriptions_controller.php

<?php
class SubscriptionsController extends AppController {
    var $name = 'Subscriptions';

    function index() {
        $this->autoRender = false;
        var_dump(is_object($this->Subscription));
        var_dump(is_object($this->Subscription->User));
    }
}
?>

The output of /users and /subscriptions should both be bool(true) bool(true).

You can see the full models by doing pr($this->User);.

Deleting records

If you delete a single record using, for example, $this->User->delete($user_id), all the records in the join table with that user ID will automatically be deleted as well.

If you want to delete a single record from a HABTM join table, without deleting the records that it links to, in effect, “unjoining” the two records, you can do it through the SubscriptionsUser model. This is a model that is created on the fly whenever there’s a HABTM relationship.

See here for an example: CakePHP hasAndBelongsToMany (HABTM) Delete Joining Record