ReadyRead() signal is not being emitted (server side)

mandruk1331

I have created a server part, and everything works ok the data is being received from the client but I can get it only If I press the button which will read the data from the socket is there any way to signal that socket is filled with data and is ready to read. I have found that I can use the ReadyRead signal but it's not being emitted when the socket has the data in it, what can be the problem and how I can solve it?
Server side code:

#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    socket = new QTcpSocket(this);
    connect(&server,SIGNAL(newConnection()),this,SLOT(newCon()));
    connect(socket,SIGNAL(readyRead()),this,SLOT(on_pushButton_clicked()));
}

MainWindow::~MainWindow()
{
    delete ui;
}
void MainWindow::ListenS(){
    qDebug()<<"Listening";
    //socket->bind(QHostAddress::LocalHost,5555,QAbstractSocket::DontShareAddress);
    if(server.listen(QHostAddress::LocalHost,5555)){
    }
}
void MainWindow::newCon(){
    ui->label->setText("Connected");
    socket->open(QIODevice::ReadWrite);
    socket = server.nextPendingConnection();
    socket->waitForReadyRead(500);
}

void MainWindow::on_pushButton_clicked()
{
    QByteArray ba;
    ui->label->setText(QString::number(socket->bytesAvailable()));
    if(socket->bytesAvailable() <=0){
        mes = "Error";
    }else{
    ba = socket->readAll();
    QString g(ba);
    mes = g;
    }
    QImage img = QImage::fromData(ba);
    ui->label->setPixmap(QPixmap::fromImage(img));
}

jsulm

@mandruk1331 You're not using the socket you connected:

socket = new QTcpSocket(this);
connect(&server,SIGNAL(newConnection()),this,SLOT(newCon()));
connect(socket,SIGNAL(readyRead()),this,SLOT(on_pushButton_clicked()));

now

socket = server.nextPendingConnection();

you need to connect the signal from the socket you get from server.nextPendingConnection();
For each new connection you get a new socket.
That's why you do not need the socket you create in the constructor. Just do:

socket = server.nextPendingConnection();
connect(socket,SIGNAL(readyRead()),this,SLOT(on_pushButton_clicked()));

J.Hilk

Hi, I'm not 100% sure, but I think your readyRead Signal is not emitted, because you call WaitForReadyRead, right after connecting, and after that, no now data arrives at the socket -> no Signal later.

@mandruk1331 said in ReadyRead() signal is not being emitted (server side):

void MainWindow::newCon(){
ui->label->setText("Connected");
socket->open(QIODevice::ReadWrite);
socket = server.nextPendingConnection();
socket->waitForReadyRead(500);
}

koahnig

@mandruk1331

Checkout the server example found here.

@mandruk1331 said in ReadyRead() signal is not being emitted (server side):

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    socket = new QTcpSocket(this);
    connect(&server,SIGNAL(newConnection()),this,SLOT(newCon()));
    connect(socket,SIGNAL(readyRead()),this,SLOT(on_pushButton_clicked()));
}

You connect your signal with a socket pointer above.

@mandruk1331 said in ReadyRead() signal is not being emitted (server side):

    void MainWindow::newCon(){
    ui->label->setText("Connected");
    socket->open(QIODevice::ReadWrite);
    socket = server.nextPendingConnection();
    socket->waitForReadyRead(500);
}

In this routine you are writting another pointer and basically disconnect this signal. Place the connect in routine newCon() after assigning the pointer.

mandruk1331

@jsulm this solution helped me. Thank you. Now I can continue working on my project.
And one more thing how I can send a response from the server?