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.