setContextProperty "TypeError: Cannot call method"

Heisenberg222

Code1

DataManager* pDataManager = new DataManager;
engine.rootContext()->setContextProperty("dataManager", pDataManager);

Code2

DataManager dataManager;
engine.rootContext()->setContextProperty("dataManager", &dataManager);

DataManager has a method posNum()
When I run the qml project, Code1 works good,Code2 shows an error "TypeError: Cannot call method 'posNum' of null".
I don't know the difference between Code1 and Code2.

SGaist

Hi,

What are the lifetime of these objects ?

Heisenberg222

@SGaist simple code in main.cpp

int main(int argc, char *argv[])
{
    QGuiApplication app(argc, argv);

    QQuickStyle::setStyle("Basic");
    QQmlApplicationEngine engine;
    QObject::connect(
        &engine,
        &QQmlApplicationEngine::objectCreationFailed,
        &app,
        []() { QCoreApplication::exit(-1); },
        Qt::QueuedConnection);

    DataManager dataManager;
    engine.rootContext()->setContextProperty("dataManager", &dataManager);

    //DataManager* pDataManager = new DataManager;
    //engine.rootContext()->setContextProperty("dataManager", pDataManager);

    engine.loadFromModule("Project", "Main");

    return app.exec();
}