Fail to invoke StackView push method from c++

oberluz

Hi,

I'm having an isssue invoking the push() method on a QML StackView from C++. The code is:

    QVariant arg("qrc:/Common/whatever.qml");
    bool ok = QMetaObject::invokeMethod(m_stackView, "push", Q_ARG(QVariant, arg));

At runtime it complains:

W libA.so: (null):0 ((null)): QMetaObject::invokeMethod: No such method QQuickStackView::push(QVariant)
W libA.so: Candidates are:
W lib.so:     push(QQmlV4Function*)

I am confused because the docs state that:

'Notice the Q_RETURN_ARG() and Q_ARG() arguments for QMetaObject::invokeMethod() must be specified as QVariant types, as this is the generic data type used for QML method parameters and return values.'

The m_stackView is a QObject* and seems correct because the error refers to a QQuickStackView.

Any ideas what I'm doing wrong?

Thanks

medyakovvit

@oberluz
Well, StackView::push() has argument of type Item. But you try to send

QVariant arg("qrc:/Common/whatever.qml");

I think, in qml it's converted to string, not an item which must to be loaded from mentioned path. So, i think, you must to load some component in c++, to use QVariant::fromValue() to create QVariant and send it to StackView::push(). For example:

QObject *stackView = engine.rootObjects().at(0)->findChild<QObject*>("myStackView"); // search element by "objectName" property
    if(stackView)
    {
        QQmlComponent component(&engine, QUrl(QStringLiteral("qrc:/StackViewMethodFromCpp.qml")));
        QObject *object = component.create();
        QVariant arg = QVariant::fromValue(object);

        if(!QMetaObject::invokeMethod(stackView, "push",
                                      Q_ARG(QVariant, arg)))
            qDebug() << "Failed to invoke push";
    }

achou

@oberluz did this solution work for you? I'm running into the same issue and when I tried @medyakovvit 's solution I still got the same error:

QMetaObject::invokeMethod: No such method QQuickStackView::push(QVariant)
Candidates are:
push(QQmlV4Function*)

I also tried to use a simple QUrl since the documentation says it can be an item, component, or url, but that led to the same error.

Thanks

jpnurmi

Why are you guys trying to invoke StackView methods directly from C++? StackView has been designed to be used from QML. Probably best if you don't let your C++ backend even know anything about the stack view. You can, for example, just emit signals from the C++ backend, and make the QML UI react to that and do the actual push. This is the normal way to communicate between C++ backends and QML UI layers.