CakePHP 2.0 twitter-like follow button - action

Question

I can't help myself and it's currently annoying, and yes, I used google a lot.
What I need:
A twitterlike follow button with the action to follow user.
What I already did:
Database
users table: id, username, password, ...
users_users table: id, user_id, follower_id
Code
In model User.php
public $hasAndBelongsToMany = array(
'Follower' => array(
'className' => 'User',
'joinTable' => 'users_users',
'foreignKey' => 'user_id',
'associationForeignKey' => 'follower_id',
'unique' => 'keepExisting',
)
);
In UsersController.php
public function follow() {
/*need help here*/
}
In Users\index.ctp
<?php if ($current_user['id'] != $user['User']['id']) echo $this->Html->link('Follow', array('action' => 'follow', $user['User']['id'])); ?>

Answer 1

Personally, I don't find hasAndBelongsToMany to be a good fit for situations like this. It's a good fit for when you want to display a list of checkboxes, or a select list, and allow the user to select/manage all their followings (or whatever the relationships might be) in one form.
It might just be my personal preference, but in situations like yours, where you're adding/deleting single links without worrying about any of the other links related to that user, I prefer to just create a separate 'Relationships' (or similarly named) Model / Controller, and consider the records as things in their own right, as opposed to just hasAndBelongsToMany links that are all sort of 'automagically' managed.
Here's how I'd do it:
Name your users_users table 'relationships'. And name the columns 'followed_by_id' and 'following_id' (or similar) to avoid any ambiguity as to which user is the follower / followee (if that was a word!).
In your users Model, you'd have these relationships:
var $hasMany = array(
'Followers' => array(
'className' => 'Relationship',
'foreignKey' => 'following_id',
'dependent'=> true
),
'FollowingUsers' => array(
'className' => 'Relationship',
'foreignKey' => 'followed_by_id',
'dependent'=> true
),
);
Then you'd have a Relationships model that looks something like this (the $belongsTo relationships are the important part):
<?php
class Relationship extends AppModel {
var $name = 'Relationship';
var $validate = array(
'followed_by_id' => array(
'numeric' => array(
'rule' => array('numeric'),
),
),
'following_id' => array(
'numeric' => array(
'rule' => array('numeric'),
),
),
);
var $belongsTo = array(
'FollowedBy' => array(
'className' => 'User',
'foreignKey' => 'followed_by_id'
),
'Following' => array(
'className' => 'User',
'foreignKey' => 'following_id'
)
);
}
?>
And then in your Relationships controller, you'd have something like this:
function add($following_id = null) {
$this->Relationship->create();
$this->Relationship->set('followed_by_id',$this->Auth->User('id'));
$this->Relationship->set('following_id',$following_id);
if ($this->Relationship->save($this->data)) {
// all good
} else {
// You could throw an error here if you want
$this->Session->setFlash(__('Error. Please, try again.', true));
}
$this->redirect($this->referer());
}
Then to add relationships, you obviously just call the add method of your relationships controller.
NOTE: Ideally, since adding a relationship is changing the database, it ideally shouldn't be done with a GET request accessed by a regular URL. It should be done via submitting a form via POST. I know that seems overkill when it's so easy to just do it via a regular link with GET. I haven't bothered to use forms/POST in this example - but if you want to stick to best practices, that's what you should do. See this for more info: https://softwareengineering.stackexchange.com/questions/188860/why-shouldnt-a-get-request-change-data-on-the-server