QML - Create ListModel dynamically (JAVASCRIPT issue)

Question

Here is my code, and it works!

ListModel {
    id: idValueList

    Component.onCompleted: {

        for (var i = 0; i < 21; i++) {
            append(createListElement(i));
        }
    }

    function createListElement(id) {
        return {
            myId: id + 1, myValue: ""
        };
    }
}

However, I need to substitute the "21" in the for loop with myXmlListModel.get(myXmlListModel.count - 1).myValue, which comes from an XmlListModel, the dynamic list model stop working!

The funny part is that the code

Text{
    x:0 ; y:0
    text: myXmlListModel.get(myXmlListModel.count - 1).myValue;
}

prints for me exactly a 21. But if I use the expression myXmlListModel.get(myXmlListModel.count - 1).myValue in the for loop, nothing works.

How can it be possible??

derM · Accepted Answer · 2017-07-10 08:53:45Z

1

The reason should be quite easy to understand:

Component.onCompleted: [...]

is executed at a very specific point in time, when the component is completed. This is not necessarily the point in time, at which the content of the myXmlListModel is available. It might be allready created, but might still be empty. Therefor when

Component.onCompleted: [...]

of your ListModel is executed, the myXmlListModel.count is indeed still 0, while changing to 21 right after - so at the time you read the Text it already has the right amount.

The point in time where you should fill your ListModel is therefor not, when it is completed, but once the content is ready, so you might handle:

myXmlListModel.onCompleted

and

myXmlListModel.onCountChanged

(for the latter you should consider to call clear() on your ListModel first)

answered Jul 10, 2017 at 8:53

derM

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