Facing issue with integration of C++ with QML

[ManiRon28]

I have started learning about QML and I started with a basic application

I am facing this issue "Cannot assign to non-existent default property"

backtest.h

#ifndef BACKTEST_H
#define BACKTEST_H

#include <QObject>

class BackTest:public QObject
{
    Q_OBJECT
    Q_PROPERTY(int iVal READ getIVal WRITE setIVal RESET resetIVal NOTIFY iValChanged FINAL)
private:
    int iVal;



public:
    BackTest();
    int getIVal() const;
    void setIVal(int newIVal);
    void resetIVal();
    signals:
        void iValChanged();
};

#endif // BACKTEST_H

backTest.cpp

#include "backtest.h"


BackTest::BackTest() {}

int BackTest::getIVal() const
{
    return iVal;
}

void BackTest::setIVal(int newIVal)
{
    if (iVal == newIVal)
        return;
    iVal = newIVal;
    Q_EMIT iValChanged();
}

void BackTest::resetIVal()
{
    setIVal({}); // TODO: Adapt to use your actual default value
}

main.cpp

#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <backtest.h>
int main(int argc, char *argv[])
{
    QGuiApplication app(argc, argv);

    QQmlApplicationEngine engine;

    qmlRegisterType<BackTest>("MyCppClassModule", 1, 0, "BackTest");

    const QUrl url(u"qrc:/untitled2/Main.qml"_qs);
    QObject::connect(
        &engine,
        &QQmlApplicationEngine::objectCreationFailed,
        &app,
        []() { QCoreApplication::exit(-1); },
        Qt::QueuedConnection);
    engine.load(url);

    return app.exec();
}

main.qml

import QtQuick
import QtQuick.Controls
import MyCppClassModule 1.0
Window {
    width: 640
    height: 480
    visible: true
    title: qsTr("Hello World")

    BackTest {
            id: myCppClassInstance
            Component.onCompleted: {
                        myCppClassInstance.iVal = 42;
                    }
            Text {
                       text: "Property value: " + myCppClassInstance.getIVal
                   }
    }
}

Kindly help me with what I am missing

[sierdzio]

@ManiRon28 I think this might be because you are trying to add Text (a visual element) as a child to BackTest which is a pure QObject, no visuals.

Try:

BackTest {
  id: myCppClassInstance
  Component.onCompleted: {
    iVal = 42;
  }
}

Text {
  text: "Property value: " + myCppClassInstance.getIVal
}

[ManiRon28]

@sierdzio Thanks it worked