Why doesn't the QQuickWidget program display when using QML Model？

[mirro]

QQuickWidget to replace the QQmlApplicationEngine in the example
https://github.com/ColinDuquesnoy/QtQuickControls2.TreeView

   QQucikWidget* pWidget = new QQucikWidget();
   pWidget->setResizeMode(QuickWidget:SizeRootObjectToView);
 
    QStandardItemModel standardItemModel;
    QStandardItem root("Root");
    root.setIcon(qtApp.style()->standardIcon(QStyle::SP_DesktopIcon));
    QStandardItem child1("Child 1");
    QStandardItem child2("Child 2");
    QStandardItem child3("Child 3");
    QStandardItem child1OfChild1("Child 1 of Child 1");
    QStandardItem child2OfChild1("Child 2 of Child 1");
    QStandardItem child1OfChild2("Child 1 of Child 2");

    child1.appendRow(&child1OfChild1);
    child1.appendRow(&child2OfChild1);
    child2.appendRow(&child1OfChild2);
    root.appendRow(&child1);
    root.appendRow(&child2);
    root.appendRow(&child3);
    standardItemModel.appendRow(&root);

    TreeViewModel standardItemTreeViewModel;
    standardItemTreeViewModel.setSourceModel(&standardItemModel);

    pWidget ->rootContext()->setContextProperty("standardItemModel", &standardItemTreeViewModel);

     pWidget ->load(QUrl("qrc:/main.qml"));
     pWidget ->show()

[J.Hilk]

@mirro do you call show() on your pWidget?

[mirro]

@J-Hilk

QQuickWidget doesn't work with QML Model ?

[SGaist]

Hi,

Depending on where that code lives, your model and all its items will be destroyed before even being used.

[mirro]

@SGaist
What should I do?Create in heap space?

TreeViewModel* pStandardItemTreeViewModel  = new TreeViewModel();
pStandardItemTreeViewModel ->setSourceModel(&standardItemModel);

pWidget ->rootContext()->setContextProperty("standardItemModel", pStandardItemTreeViewModel  );

[SGaist]

You do not provide enough code to get a proper answer. There's not enough context.

[mirro]

@SGaist

I used QQuickWidget to replace the QQmlApplicationEngine in the follow example of this url.
https://github.com/ColinDuquesnoy/QtQuickControls2.TreeView

[eyllanesc]

@mirro create QStandardItemModel standardItemModel and standardItemTreeViewModel in the heap. The explanation is simple: local variables are removed at the end of their scope and that is not what you want.