QML ListModel: remove: indices out of range

[hcaslan]

When i try to delete from listmodel i get an error like this;
--> QML ListModel: remove: indices [2 - 3] out of range [0 - 1]
The purpose of the code is to create a multiselect-combobox and output the selections made with this combobox. (This is a lesson assignment. And ı have to use combobox and listview.)

import QtQuick 2.9
import QtQuick.Window 2.2
import QtQuick.Controls 2.2

ApplicationWindow {
    id: applicationWindow
    visible: true;
    width: 640
    height: 480

    ListModel {
        id: listmodelId
    }
    ComboBox {
        id: comboboxId
        width: parent.width / 2
        height: 50
        displayText: "SELECT"
        model: ListModel {
            ListElement { name: "One";   turk: "bir";   fill: "red"}
            ListElement { name: "Two";   turk: "iki";   fill: "green"}
            ListElement { name: "Three"; turk: "uc" ;   fill: "blue"}
            ListElement { name: "Four"; turk: "dort" ;   fill: "pink"}
            ListElement { name: "Five"; turk: "bes" ;  fill: "yellow"}
            ListElement { name: "Six"; turk: "alti" ;  fill: "orange"}
            ListElement { name: "Seven"; turk: "yedi" ;   fill: "purple"}
        }
        delegate: Item {
            width: parent.width
            height: 50
            Row {
                spacing: 5
                anchors.fill: parent
                anchors.margins: 5
                CheckDelegate {
                    id: checkboxId
                    height: parent.height
                    width: height
                    onCheckStateChanged: {
                        if (checkState === Qt.Checked){
                            console.log("index Checked= "+index)
                            listmodelId.append({ "name": name, "turk":turk, "fill": fill })
                        }
                        if(checkState === Qt.Unchecked) {
                            console.log("index Unchecked= "+index)
                            listmodelId.remove(index);
                        }
                    }
                }
                Label {
                    text: name
                    width: parent.width - checkboxId.width
                    height: parent.height
                    verticalAlignment: Qt.AlignVCenter
                    horizontalAlignment: Qt.AlignHCenter
                }
            }
        }
    }
    ListView {
        id: listviewId
        width: parent.width / 2
        height: parent.height
        anchors.left: comboboxId.right
        model: listmodelId
        delegate: Item {
            height: 50
            width: parent.width
            Rectangle {
                anchors.fill: parent
                color: fill
                Text {
                    anchors.centerIn: parent
                    text: name+"     "+turk
                }
                Button{
                    text: "delete"
                    onClicked:{
                        listmodelId.remove(index)
                    }
                }
            }
        }
        onCountChanged: console.log(count)
    }
}```

[Bob64]

@hcaslan I haven't looked at this in detail but I think it might be because the index you are using to pass to remove is the model index for the combo box model, but you are calling remove on the listmodelId model, and this model is not directly related to what is being shown in the combo.

[hcaslan]

@Bob64 Yes, I understand what you're talking about. Thanks!! now the problem has become even more complicated for me(LOL). How can I add an item with pre-selected index to a listviev? any idea ?

[Bob64]

If the requirement is, as you say, simply to output the selections, the simplest way might be to clear the output list and rebuild it every time a selection is changed. Then you just need to loop over the combo list and add the items that are selected.

I have noticed that you are not storing the check state in your combo model. You would need to do this to implement what I just suggested, but in any case I think you can't rely on the delegate to store the checked state. You might get away with it here, but in general, and especially if you had a longer list in your combo, delegates can get "recycled" in the view so you cannot rely on them holding any state.