Treeview model properties are null in delegate warning

Question

I have a TreeView

TreeView {
        id: dndView
        rowDelegate: Item {
            height: 30
        }
        itemDelegate:  dndDelegate
        model: myModel
        TableViewColumn {
            title: "Name"
            resizable: true
        }
}

and its delegate which does work

Rectangle {
    id: dragRect
    anchors.horizontalCenter: parent.horizontalCenter
    anchors.verticalCenter: parent.verticalCenter
    color: 'gray'
    width: dndView.width - 20
    height: 30
    Image {
        id: menuItemImage
        anchors.verticalCenter:parent.verticalCenter
        source:model.CommandIcon
    }
    Text {
        anchors.left:menuItemImage.right
        anchors.verticalCenter:parent.verticalCenter
        text:model.CommandTitle
        font.pixelSize: 14
    }

Roles in C++ file:

QHash<int, QByteArray> MenuTreeModel::roleNames() const {
    QHash<int, QByteArray> roles;
    roles[TitleRole] = "CommandTitle";
    roles[IconRole] = "CommandIcon";
    return roles;
}

It displays text and icon correctly but nevertheless when I expand the items or close the application I have warnings:

qrc:/DraggableRectangle.qml:15: TypeError: Cannot read property 'CommandIcon' of null qrc:/DraggableRectangle.qml:20: TypeError: Cannot read property 'CommandTitle' of null*

What's wrong with it?

Answer 1

If the warnings only appear on specific events, it may mean the model is destroyed or not yet created when your QML view tries to use it.

E.g. if the model is destroyed before the view when you close the application, the view still tries to use a destroyed object for a short time (before it's destroyed too).

Try this :

text: model ? model.CommandTitle : ""