WebUser.php

<?php 
class WebUser extends CWebUser {

    public function checkAccess($operation, $params = array()) {
        if (empty($this->id)) {
            return false;
        }
        $role = $this->getState("roles");
        if ($role === 'admin') {
            return true;
        }
        return ($operation === $role);
    }

}
?>