public function isValid()
    {
        foreach ($this->validators as $validator) {
            if (!$validator->isValid()) {
                // Prepare error messages
                foreach ($validator->getErrors() as $name => $messages) {
                    if (!isset($this->errors[$name])) {
                        $this->errors[$name] = array();
                    }

                    $this->errors[$name] = $messages;
                }
            }
        }

        return !$this->hasErrors();
    }