Create sub a ListModel

Merinas

Hi,

I need to create a sub list of a ListModel, For example I have huge list of things and I want to get them by 10, like I could want a sub list which start width the 8th element and take 12 of them.

What's the best way of doing that ?

Thanks a lot.

andre

I guess it depends on what you really need.

My first hunch would be to subclass a QSortFilterProxyModel, and expose that with some relevant properties to QML to provide the data you need.

Merinas

Thanks for answering. I need that : @
ListModel{
id:lmodel
//[...]
}

SubListModel{
id:lmodel1
source:lmodel
range.start:0
range.lenght:10
}

ListView{
model:lmodel1
//[...]
}@

Is it possible with your suggestion ?

andre

Not with just QML, no. My suggestion would take C++ to realize.

Merinas

Ok, I get that, so subclass a QSortFilterProxyModel would solve my problem ?

andre

It could, if your data doesn't come from within QML. If you can get your data from the C++ side, you can use this approach. The problem is that you can not use a QSortFilterProxyModel on a model that comes from QML, but only on a QAbstractItemModel-derived model.

Merinas

Arf... My data came from a QML ListModel since I work only with QML and some few C++plugins.

mario

Well, maybe you can do it by adding a javascript-function that will loop through your ListModel (lmodel) and add the desired item to other ListModel (lmodel1).

Merinas

That's what I think of, but I'm not quite sure I can do that : @list.append(list2.get(i))@

mario

Is this what you're looking for?

@
import QtQuick 1.0

Rectangle {
id: main

width: 400
height: 600

ListModel {
    id: myModel

    ListElement {
        name: "element 0"
    }
    ListElement {
        name: "element 1"
    }
    ListElement {
        name: "element 2"
    }
    ListElement {
        name: "element 3"
    }
}

ListModel {
    id: subList
}


ListView {
    id: listView

    anchors.fill: parent

    spacing: 8

    model: subList
    delegate: Text { text: name; width: listView.width }
}

Text {
    text: "Update list"
    anchors.right: parent.right; anchors.bottom: parent.bottom; anchors.margins: 5
    MouseArea {
        anchors.fill: parent
        onClicked: updateSubList(1, 2)
    }
}

function updateSubList(begin, end) {
    subList.clear()
    end = Math.min(end, myModel.count-1)
    for (var i = begin; i <= end ; i++) {
        subList.append(myModel.get(i))
    }
}

}
@

Merinas

Yeah that should do the tricks, thanks a lot.....
And what happen if the source model change ? Is there a signal emit somewhere, or did i need to build one ?

mario

I actually tried connecting to a 'onCountChanged' signal on the ListModel but w/o success. Don't know if that is a bug or feature :)