public function getField($key, $validate = false) {
        $field = $key;
        if (!array_key_exists($key, $this->_fieldMeta)) {
            if (array_key_exists($key, $this->_fieldAliases)) {
                $field = $this->_fieldAliases[$key];
            } elseif ($validate === true) {
                $field = false;
            }
        }
        return $field;
    }