QUdpSocket readReady not emitting signal - qt

Question

I'm just getting started with implementing a UDP client for my Qt application. I followed this example. I am able to send data to and receive data from a remote host. This has been verified at my remote host as well as the local client that I am developing this application for (verified locally by calling handleReadyRead() from my main.cpp). I can't seem to get the QUdpSocket to emit its readyRead signal. Why is that?
main.cpp
#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QTimer>
#include "udpclient.h"
static double value = 0;
static bool flash = true;
static UDPClient client;
int update1000()
{
QByteArray Data;
Data.append((char) 0x00);
Data.append((char) 0x2c);
Data.append((char) 0x1a);
Data.append((char) 0x2c);
Data.append((char) 0x92);
Data.append((char) 0xe6);
Data.append((char) 0xf6);
Data.append((char) 0xa0);
client.SendPacket(Data);
return 0;
}
int packetReady()
{
qInfo() << "packetReady";
return 0;
}
int main(int argc, char *argv[])
{
QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
QGuiApplication app(argc, argv);
qmlRegisterType<HorizontalBarGraph>("com.kubie.horizontalBarGraph", 1, 0, "HorizontalBarGraph");
QQmlApplicationEngine engine;
engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
if (engine.rootObjects().isEmpty())
return -1;
QObject *object = engine.rootObjects()[0];
//qInfo() << "Initializing timer.";
QTimer timer1000;
QObject::connect(&timer1000, &QTimer::timeout, update1000);
timer1000.start(1000);
return app.exec();
}
udpclient.h
#ifndef UDPCLIENT_H
#define UDPCLIENT_H
#include <QUdpSocket>
class UDPClient : public QObject
{
Q_OBJECT
public:
explicit UDPClient(QObject *parent = nullptr);
void SendPacket(const QByteArray &buffer);
private:
QUdpSocket *socket = nullptr;
signals:
public slots:
void handleReadyRead();
};
#endif // UDPCLIENT_H
udpclient.cpp
#include "udpclient.h"
UDPClient::UDPClient(QObject *parent) :
QObject(parent)
{
socket = new QUdpSocket(this);
//We need to bind the UDP socket to an address and a port
//socket->bind(QHostAddress::LocalHost,1234); //ex. Address localhost, port 1234
socket->bind(QHostAddress::AnyIPv4,6969); //ex. Address localhost, port 1234
//connect(socket,SIGNAL(readyRead()),this,SLOT(handleReadyRead()));
connect(socket, &QUdpSocket::readyRead, this, &UDPClient::handleReadyRead);
}
void UDPClient::SendPacket(const QByteArray &buffer)
{
socket->writeDatagram(buffer, QHostAddress("192.168.174.10"), 6969);
}
void UDPClient::handleReadyRead() //Read something
{
qInfo() << socket->hasPendingDatagrams();
QByteArray Buffer;
Buffer.resize(socket->pendingDatagramSize());
QHostAddress sender;
quint16 senderPort;
socket->readDatagram(Buffer.data(),Buffer.size(),&sender,&senderPort);
qInfo() << Buffer;
//The address will be sender.toString()
}

Answer 1

A QML application needs (at least) a QGuiApplication to run. You will get a debug output on the command line or in your IDE debug application output window about this. To get a more fatal warning for such kind of problems you can set the environment variable QT_FATAL_WARNINGS (see QDebug documentation for more information)