foo.php

<?php
    /**
     * Configures authentication and the basic fields to show on each screen
     *
     * @param Event $event The given event
     * @return void
     */
    public function beforeFilter(Event $event)
    {
        if ($this->request->public) {
            $this->Auth->allow();
        }

        parent::beforeFilter($event);
        
        // Attach an event listener to the main model
        $this->loadModel()
            ->eventManager()
            ->on(new RequestMetadata($this->request, $this->Auth->user('username')));
    }