Qt QTcpSocket streaming

My application sent object to the server via QTcpSocket.

Client:

void client::sendFile(QString path)
{
    QFile toSend(path);
    QByteArray rawFile;
    rawFile = toSend.readAll();

    QDataStream out(cl);
    out >> rawFile;
}

Server:

void server::handleClient()
{
    QTcpSocket *curCl = srv->nextPendingConnection();
    QByteArray z;
    QDataStream in(curCl);
    in >> z;

    QFile qwe("test.dat");
    qwe.write(z);
    qwe.close();
}

The problem is that nothing happens, but debug console told me:

QIODevice::write: device not open
QIODevice::read: device not open

... but the QDataStream object doesn't allow me to set open mode up! :( Whats wrong?

QFile + QFile.write (or QFile.read) requires QFile.open, see example:

Write:

QFile qwe("test.dat");
if(qwe.open(QIODevice::WriteOnly | QIODevice::Text)) {
  qwe.write(z);
  qwe.close();
} else {
  qDebug() << "Error";
}

or

#include <QTextStream>

...

QFile qwe("test.dat");
if(qwe.open(QIODevice::WriteOnly | QIODevice::Text)){
   QTextStream out(&qwe);
   out << "This file is generated by Qt\n";
   qwe.close();
} else {
  qDebug() << "Error";
}

Read:

QFile toSend(path);
if(toSend.open(QIODevice::ReadOnly | QIODevice::Text)) {//Open "read file"
    QByteArray rawFile;
    rawFile = toSend.readAll();

    QDataStream out(cl);
    out >> rawFile;
    toSend.close();//close
}