Attach Comments to Any Model in CakePHP

October 5th, 2008 - brett

This method of linking models allows you to have a single table of data, say Comment, that is related to any one of a number of other Models (eg: Post, Event).

The Models

Before we get started, lets setup the models.

models/comment.php

class Comment extends AppModel {

        var $name = 'Comment';

}

models/post.php

class Post extends AppModel {

        var $name = 'Post';

        var $hasMany = array(

                'Comment' => array(

                        'className' => 'Comment',

                        'foreignKey' => 'foreign_id',

                        'conditions' => array('Comment.class'=>'Post'),

                ),

        );

}

models/event.php

class Event extends AppModel {

        var $name = 'Event';

        var $hasMany = array(

                'Comment' => array(

                        'className' => 'Comment',

                        'foreignKey' => 'foreign_id',

                        'conditions' => array('Comment.class'=>'Event'),

                ),

        );

}

The Controller

Now to save the data.

views/posts/view.ctp

<?php echo $form->create('Post');?>

        <fieldset>

                <legend><?php __('Post Details');?></legend>

        <?php

                echo $form->input('Comment.name');

                echo $form->input('Comment.body');

        ?>

        </fieldset>

<?php echo $form->end('Submit');?>

controllers/posts_controller.php

class PostsController extends AppController {

        var $name = 'Posts';

        function view($id = null) {

                if (!$id) {

                        $this->_flash(__('Invalid Post.', true),'error');

                        $this->redirect(array('action'=>'index'));

                }

                // save the comment

                if (!empty($this->data['Comment'])) {

                        $this->data['Comment']['class'] = 'Post'; 

                        $this->data['Comment']['foreign_id'] = $id; 

                        $this->Post->Comment->create(); 

                        if ($this->Post->Comment->save($this->data)) {

                                $this->_flash(__('The Comment has been saved.', true),'success');

                                $this->redirect(array('action'=>'view',$id));

                        }

                        $this->_flash(__('The Comment could not be saved. Please, try again.', true),'warning');

                }

                // set the view variables

                $post = $this->Post->read(null, $id); // contains $post['Comments']

                $this->set(compact('post'));

        }

}