public function getMessages()
    {
        $messages = array();
        foreach ($this->_fields as $fieldName => $values) {
            if (! $values['isValid']) {
                $invalidators = array();
                foreach ($values['validators'] as $validatorName => $validatorValue) {
                    if (! $validatorValue) {
                        $invalidators[] = $validatorName;
                    }
                }
                $messages[$fieldName] = $invalidators;
                unset($validator);
            }
            unset($fieldName);
            unset($values);
        }
        return $messages;
    }