Shuffle QML ListModel

Question

I have a ListModel and a repeater. The repeater draws the Items from the ListModel, one on top of a another. That works fine so far.

Except that for on each application start I want to have a different draw order.

So i guess it would be best, to "shuffle" the ListElements in the ListModel before applying the Repeater. How can I do this?

Answer 1

Using the following answers:

• https://stackoverflow.com/a/2450976/6622587
• https://stackoverflow.com/a/36645492/6622587

And adapting for a ListModel you get the following function:

utils.js

//https://stackoverflow.com/a/2450976/6622587
function shuffle(model){
    var currentIndex = model.count, temporaryValue, randomIndex;

    // While there remain elements to shuffle...
    while (0 !== currentIndex) {
        // Pick a remaining element...
        randomIndex = Math.floor(Math.random() * currentIndex)
        currentIndex -= 1
        // And swap it with the current element.
        // the dictionaries maintain their reference so a copy should be made
        // https://stackoverflow.com/a/36645492/6622587
        temporaryValue = JSON.parse(JSON.stringify(model.get(currentIndex)))
        model.set(currentIndex, model.get(randomIndex))
        model.set(randomIndex, temporaryValue);
    }
    return model;
}

main.qml

import QtQuick 2.9
import QtQuick.Window 2.2
import "utils.js" as Util

Window {
    visible: true
    width: 640
    height: 480
    title: qsTr("Hello World")

    ListModel {
        id: fruitModel
        ListElement {
            name: "Apple"
            cost: 2.45
        }
        ListElement {
            name: "Banana"
            cost: 1.95
        }
        ListElement {
            name: "Orange"
            cost: 3.25
        }
    }

    Column {
        Repeater {
            model: Util.shuffle(fruitModel)
            Row {
                spacing: 10
                Text { text: name }
                Text { text: '$' + cost }
            }
        }
    }
}

In this link you can find an example.

Answer 2

How about function call and then return model.

function shuffle(n)
{
     if(n === 1)
         return ["apples", "oranges", "pears"];
     else if(n === 2)
         return ["banana", "oranges", "pears"];
}

Column {
    Repeater {
        model: shuffle(1)
        Text { text: "Data: " + modelData }
    }
}