Updating QAbstractItemModel: Model is null although begin/endResetModel have been called?

maxwell31

Hi,

I have a QAbstractItemModel in c++ which I use in a TreeView. This is working fine. When the data changes I call a reset function:

void MyTreeModel::reset(TreeBase* tb) {
    beginResetModel();
    setRootNode(tb);
    endResetModel();
}

The update works, but I get errors of the form

qrc:/TreeViewScreen.qml:339: TypeError: Cannot read property 'FirstProperty' of null

The error shows up 3 times for every entry. What am I missing? I thought that the begin/endResetModel would be enough to notify the view.

raven-worx

@maxwell31 said in Updating QAbstractItemModel: Model is null although begin/endResetModel have been called?:

The update works, but I get errors of the form
qrc:/TreeViewScreen.qml:339: TypeError: Cannot read property 'FirstProperty' of null

show some more (QML) code.

maxwell31

My model is set as a contextProperty in c++:

_myTreeModel = new MyTreeModel
_engine->rootContext()->setContextProperty("treeModel", _myTreeModel);
qmlRegisterUncreatableType<MyTreeModel>("MyTreeModel",1,0,"TreeModel", "problem treemodel");

In the QML file I use it like this

QC1.TreeView {
    id: treeView
    model: treeModel
    anchors.fill: parent

    QC1.TableViewColumn {
    width: 270
    id: namecolumn
    title: "Name"
    role: "Name"

    }
    QC1.TableViewColumn {
    id: namecolumn2
    title: "Value"
    role: "FirstProperty"
    delegate: myDelegate
    }
}

and the delegate is

Component {
    id: myDelegate
    Loader { // loader choosing the right component
    property var firstProperty: model.FirstProperty
    property string typeString: model.Type
    property var thisIndex: styleData.index
    sourceComponent: if(typeString=='bool') {
                        checkBoxDelegate
                    }
                    else if(typeString=='double') {
                        floatDelegate
                    }
                    else if(typeString=='int32_t') {
                        floatDelegate
                    }
                    else { stringDelegate}
    }
}
Component {
    id: checkBoxDelegate
    CheckBox{text: ""
    anchors.bottom: parent.bottom
    anchors.bottomMargin: 2
    checked: treeModel.data(thisIndex,TreeModel.FirstProperty)
    onCheckedChanged: {
        treeModel.setData(thisIndex, checked,TreeModel.FirstProperty)
    }
    }
}

as you see I load different delegates, depending on the type.

raven-worx

@maxwell31
see this example.
It may be that only the delegate component itself gets the properties assigned

maxwell31

I fear I don't understand what you mean

Diracsbracket

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