Qt issue C++/QML

I want to access model data in c++, not in qml
Below is the code.

QHash<int, QByteArray> XItemList::roleNames() const noexcept override
{
    static auto roles = QHash<int, QByteArray>{
        { ID, "id" },
        { Name, "name" },
        { Size, "size"}
    };

    return roles;
}

QVariant XItemList::data(const QModelIndex &idx, int role) const override
{
    ...
    switch(role)
    {
    case ID:
        ...
        return XXX;
        break;
    case Name:
        ...
        return XXX;
        break;
    case Size:
        ...
        return XXX;
        break;
    }
    ...
}



ListView {
    model: controller.itemlist

    delegate: Rectangle {

        Label {
            ...
            text: modelData.id
        }


        Label {
            ...
            text: modelData.item_name
        }

        Label {
            ...
            text: modelData.size
        }
    }
}

...
...
XItemList item_list = container->getXItemList();
here I want to get list of all data of item_list
How can I do that?

The result I want looks like this
QList<XItem> result_list;
and each XItem contains id, name and size