security.yml

FacebookProvider.php

<?php

// snip
    /**
     * Find user by email
     *
     * @param string $email
     *
     * @return mixed
     */
    public function findUserByEmail($email)
    {
        return $this->userManager->findUserBy(array('email' => $email));
    }

    /**
     * {@inheritDoc}
     */
    public function loadUserByUsername($username)
    {
        $user = $this->findUserByFbId($username);

        try {
            $fbdata = $this->facebook->api('/me');
        } catch (FacebookApiException $e) {
            $fbdata = null;
        }

        if (!empty($fbdata)) {
            if (null === $user) {
                $user = $this->findUserByEmail($fbdata['email']);
            }

            if (null === $user) {
                $user = $this->userManager->createUser();
                $user->setEnabled(true);
                $user->setPassword('');
            }

            // TODO use http://developers.facebook.com/docs/api/realtime
            $user->setFBData($fbdata);

            if (count($this->validator->validate($user, 'Facebook'))) {
                // TODO: the user was found obviously, but doesnt match our expectations, do something smart
                throw new UsernameNotFoundException('The facebook user could not be stored');
            }
            $this->userManager->updateUser($user);
        }

        if (empty($user)) {
            throw new UsernameNotFoundException('The user is not authenticated on facebook');
        }

        return $user;
    }

// <snip>

security.yml

security:
    providers:    
        my_facebook_provider:
            id: my_user_bundle.facebook.user

    firewalls:
        // ...

        public:
            fos_facebook:
                app_url: "https://developers.facebook.com/apps/<YOURAPPKEY>/"
                server_url: "<SERVERURL>"
                login_path: /login
                check_path: /login_fb_check
                default_target_path: /
                provider: my_facebook_provider
            logout:
                handlers: ["fos_facebook.logout_handler"]
            // ...

User.php

<?php

// <snip>

    /**
     * @param string $facebookId
     *
     * @return User
     */
    public function setFacebookId($facebookId)
    {
        $this->facebookId = $facebookId;

        if (!$this->username) {
            $this->setUsername($facebookId);
            $this->salt = '';
        }

        return $this;
    }

// <snip>

    /**
     * @param array $fbdata
     */
    public function setFBData($fbdata)
    {
        if (isset($fbdata['id'])) {
            $this->setFacebookId($fbdata['id']);
            $this->addRole('ROLE_FACEBOOK');
        }
        if (isset($fbdata['first_name'])) {
            $this->setFirstname($fbdata['first_name']);
        }
        if (isset($fbdata['last_name'])) {
            $this->setLastname($fbdata['last_name']);
        }
        if (isset($fbdata['email'])) {
            $this->setEmail($fbdata['email']);
        }
    }

// <snip>