RainLab\Translate\Models\Message::toLocale PHP Method

    public function toLocale($locale = null, $message)
    {
        if ($locale === null) {
            return;
        }
        $data = $this->message_data;
        $data[$locale] = $message;
        if (!$message) {
            unset($data[$locale]);
        }
        $this->message_data = $data;
        $this->save();
    }