将HABTM记录保存到数据库CakePHP

Question

I am working on a followers / following system with CakePHP 2. I have setup my database with a users table, and a user_users table. The users table is the main table containing every user on the system, whilst the user_users table contains the records of followers.

I then have a UsersController, User model and Follower model.

I can successful output a button to either say Follow or Following dependent on whether the currently logged in user is following the user of which the profile they are viewing belongs to, however what I am unable to understand how to do, is create new following relationships in the table. In other words, I do not know how to create records in the user_users table.

I am not sure where the logic for this should go, and thus what my "Follow" button should point to.

This is probably a very simple question, but I am totally stumped. I have tried adding a "follow" action to the UsersController but I cannot get that to work.

Any help much appreciated, Duncan

Answer 1

HATBM isn't a good fit in this situation. From the cookbook :

HABTM data is treated like a complete set, each time a new data association is added the complete set of associated rows in database is dropped and created again so you will always need to pass the whole data set for saving. For an alternative to using HABTM see hasMany through (The Join Model)

For this reason, HABTM is mainly good for pretty 'dumb' relationships. I've used it in cases such as where a User has to select many Interests - and they just get a list of checkboxes, where they can click multiple Interests, and save them all in one hit.

In your case, it'll be easier to have a separate table with it's own model. I'd call it Relationships or something similar. It would have an id, followed_by_id, following_id, and any other fields you may need.

I've dug up some code from an old cake 1.3 app, but it should help you out. Your Relationships model would look something like this:

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

    var $belongsTo = array(
        'FollowedBy' => array(
            'className' => 'User',
            'foreignKey' => 'followed_by_id'
        ),
        'Following' => array(
            'className' => 'User',
            'foreignKey' => 'following_id'
        )
    );
}
?>

Your User's model would have to have relationships like this:

var $hasMany = array(
    'Followers' => array(
        'className' => 'Relationship',
        'foreignKey' => 'following_id',
        'dependent'=> true
    ),
    'FollowingUsers' => array(
        'className' => 'Relationship',
        'foreignKey' => 'followed_by_id',
        'dependent'=> true
    ),

);

Then in your relationships controller, you'd have methods 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);
    $this->Relationship->save();
    $this->redirect($this->referer());
}

function delete($id = null) {
    $this->Relationship->delete($id);
    $this->redirect($this->referer());
}

Note that in that code, I'm modifying the database with a GET request - which I really shouldn't be doing (it's old code, from years ago). You'll want to enforce a POST request for both the add and delete methods, since they're modifying the database.

But still, that code should set you on the right track.