Qt POST to QString

QObject::connect(manager, SIGNAL(finished(QNetworkReply*)), this, SLOT(finish_get(QNetworkReply*)));

void connecter::finish_get(QNetworkReply *reply)
{
    QByteArray bytes = reply->readAll();
    qDebug() << QString::fromUtf8(bytes.data(), bytes.size());
}

$this->answer = reply->readAll();

class Downloader : public QObject {
    Q_OBJECT
    public:
        Downloader(QObject * = 0);
        void download(QString);

    signals:
        void downloaded(QByteArray);
        void error(QString);

    private slots:
        void dataReady(QNetworkReply*);

    private:
        QNetworkAccessManager   network_manager;
};

Downloader::Downloader(QObject *parent)
    : QObject(parent) {
    connect(&network_manager,
            &QNetworkAccessManager::finished,
            this,
            &Downloader::dataReady);
}

void Downloader::download(QString u) {
    QNetworkRequest     request(QUrl(u));
    network_manager.get(request);
}

void Downloader::dataReady(QNetworkReply *reply) {
    if(reply -> error() != QNetworkReply::NoError) {
        emit error("...");
        return;
    }
    QByteArray  array = reply -> readAll();
    emit arrayDownloaded(array);
    reply -> deleteLater();
}

QMap<QString, QVariant>     map;
QJsonDocument               doc;
doc = QJsonDocument::fromJson(data.toLocal8Bit().data());
map = doc.toVariant().toMap();
emit dataReceived(map);