QSerialPort::readyRead couldn't connect to my slot.

Enem

//mainwindow.cpp
#include "mainwindow.h"
#include "./ui_mainwindow.h"

#include <QMetaMethod>
#include <QSerialPort>
#include <QSerialPortInfo>

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    serialPort = new QSerialPort(this);
    serialPort->setPortName("COM4");
    serialPort->setBaudRate(QSerialPort::Baud9600);
    serialPort->setDataBits(QSerialPort::Data8);
    serialPort->setParity(QSerialPort::NoParity);
    serialPort->setStopBits(QSerialPort::OneStop);
    serialPort->setFlowControl(QSerialPort::NoFlowControl);

    serialPort->open(QIODevice::ReadWrite);
    if(serialPort->isOpen())
        serialPort->write("*IDN?\n");

    connect(serialPort, &QSerialPort::readyRead, this, &MainWindow::readData);

    if(isSignalConnected(QMetaMethod::fromSignal(&QSerialPort::readyRead)))
        qDebug() << "connected";
    else
        qDebug() << "disconnected";
}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::readData(){
    static QByteArray ba;

    size_t current = 0;
    if(serialPort->waitForBytesWritten(1000)){

    }

    if(serialPort->waitForReadyRead(1000)){

    }
    if(serialPort->bytesAvailable()){
        ba = serialPort->readAll();
    }

}

//mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>

QT_BEGIN_NAMESPACE
namespace Ui {
class MainWindow;
}
QT_END_NAMESPACE

class QSerialPort;

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

private:
    Ui::MainWindow *ui;
    QSerialPort* serialPort;
private slots:
    void readData();
};
#endif // MAINWINDOW_H

This is minimal example to reproduce the error.
QObject::connect returns false when i try to connect QSerialPort::readyRead to MainWindow::readData slot. A lambda instead of class member function also doesn't work.
How could I fix this? What I'm doing wrong? Please, help me to figure it out.
Extra question: How will this work for multiple theads?
EDIT:
Qt version is 6.6.1. Compiler is MinGW 64-bit. Project generate system is cmake

jsulm

@Enem said in QSerialPort::readyRead couldn't connect to my slot.:

if(isSignalConnected(QMetaMethod::fromSignal(&QSerialPort::readyRead)))
qDebug() << "connected";
else
qDebug() << "disconnected";

Why don't you simply check the return value of your connect(...) call?

Read https://doc.qt.io/qt-6/qobject.html#isSignalConnected
"signal must be a signal member of this object, otherwise the behaviour is undefined"
This is exactly what you're doing wrong.

Christian Ehrlicher

This post is deleted!

Enem

@jsulm
Oh, this is stupid mistake. I'm tired and I can't see anything in front of me. Very grateful to you!