Question

I ran into a problem the other day where the PagesController was throwing the following error:

Fatal error: Call to a member function
find() on a non-object in
/home/jmccreary/www/thoroughbredsource.com/cakephp/app/app_controller.php
on line 20

app_controller.php line 20:

$this->current_user = $this->User->find('first', array('recursive' => 0,
  'conditions' => array('User.id' => $this->logged_in_user_id)));

In this case $this was an instance of PagesController, but for whatever reason had not inherited the User model from app_controller.php.

For completeness, here’s the relevant code:

pages_controller.php

var $name = 'Pages';
var $uses = null;

function beforeFilter() {
    parent::beforeFilter();

    $this->Auth->allow('*');
}

app_controller.php

var $uses = array('User');
var $components = array('Session', 'Cookie', 'RequestHandler', 'DebugKit.Toolbar', 'Auth' => array('autoRedirect' => false, 'loginRedirect' => array('controller' => 'users', 'action' => 'dashboard'), 'flashElement' => 'error', 'loginError' => 'The username or password you provided are incorrect.', 'authError' => 'Please log in first.', 'fields' => array('username' => 'email', 'password' => 'passwd'), 'userScope' => array('User.active' => 1)));
var $helpers = array('Html', 'Form', 'Session');

function beforeFilter() {
    parent::beforeFilter();

    // configure Cookie Component
    // ...

    $this->logged_in_user_id = $this->Auth->user('id');
    if ($this->logged_in_user_id) {
        // NOTE: the following runs on each request for the logged in user
        $this->current_user = $this->User->find('first', array('recursive' => 0, 'conditions' => array('User.id' => $this->logged_in_user_id)));
    }
}

I got past this error by change var $uses = null; to var $uses = array();. Note that removing this line completely resulted in the same error.

In the end, I don’t fully understand the original problem or my solution. I would appreciate a better explanation or what the appropriate solution should be. BTW, running CakePHP 1.3.10.

Answer 1

According to the Controller class’ source source which you can see at http://api.cakephp.org/view_source/controller/:

/**
 * An array containing the class names of models this controller uses.
 *
 * Example: `var $uses = array('Product', 'Post', 'Comment');`
 *
 * Can be set to array() to use no models.  Can be set to false to
 * use no models and prevent the merging of $uses with AppController
 *
 * @var mixed A single name as a string or a list of names as an array.
 * @access protected
 * @link http://book.cakephp.org/view/961/components-helpers-and-uses
 */
    var $uses = false;

By using $uses = array(), you’re telling the PagesController to “use no model and merge with AppController’ $uses” so it works. You can see the merge in the source code starting on line 399. From what I can see, it treats “null” the same as “false” which means that it won’t load any model including the ones from the AppController.

You can also see http://book.cakephp.org/view/961/components-helpers-and-uses for additional information on $uses.