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How to Assing an id property for dynamically created element.

  • This is Javascript code

    function createComboBox(row, column)
    if (component == null)
    component = Qt.createComponent("CompoBox.qml");

    if (component.status == Component.Ready) {
        var dynamicObject = component.createObject(cell);
        if (dynamicObject == null) {
            console.log("error creating Cell");
            return false;
        dynamicObject.width = gridColumn.cellWidth;
        dynamicObject.height = gridColumn.cellHeight; = ?????
    } else {
        console.log("error creating Comobobox");
        return false;
    return true;


  • I dont understand what you want do.

  • AFAIK you cannot set id of a QML element from c++

  • Hi,

    It isn't possible to add an id to a dynamically created object (the set of ids in a component is considered static). Can you say any more about what you want to use the id for? There might be some alternative methods/workarounds for achieving what you are after.


  • thanks stuk, QtK and mbrasser

    I want to create a grid dynamically , the dataset is SQL table I don't know the the fields and the datatypes which the user may select using SELECT statment.

  • you don't need an id for dynamic object, just use object name to operate

  • suppose I use another javascript function to create more than one object using the previous function??
    the id or name has to be unique ,I think it should be created dynamically

  • It might be helpful to look at the samegame demo, which manages a large number of dynamically created objects (all of the balls are dynamically created). If you are presenting data from a dataset, I'd also suggest seeing if you can accomplish what you need with the model/view (or model with Repeater) architecture, as it takes care of the object management tasks for you.


  • thank you mbrasser

    I tired all the ways you had suggest,in the samegame they redraw the objects again but that will be slow and boring, if we can access the object directly ,we will decrease the code and cost.

  • If you use a ListModel/Delegate method, of course, you do not have such a problem as you can refer to each item by an index. You can also get item at mouse coords (or x,y coords).

    You can use a ListModel/Delegate to dynamically create items inside a GridView in exactly the way you seem to be doing.

    Also, if you use any sort of List/indexed element (Flow), you will have the same functionality.

    So basically, the only area this falls down is if you try to use id's from non-QML code.

    Solution: Use QML.

  • Mr xsacha
    You have no way to dynamically make a grid using ListModel/Delegate with one dataset!! so you have to draw the grid and populate it with suitable data.

    the cell has to make sense to the user actions regardless of the GridComponent so the need to Know the id is very required

  • You can add elements to a model at any time (dynamically).
    Each element can be uniquely identified with a property (eg. name) or an index.

    I don't understand what you mean but I assume you think the model is limited to static ListElements?

    You can use insert (or append):
    @fruitModel.insert(2, {"cost": 5.95, "name":"Pizza", "shape":"Rectangle"})@

    You can dynamically change properties:
    @fruitModel.setProperty(index, "cost", cost * 2)@

    You can then refer to these elements:
    @grid.indexAt(mouseX, mouseY)@

  • but you have no way to make a grid using one model??

  • @
    Component {
    id: widgetDelegate
    Rectangle {
    width: 80; height: 80
    radius: shape == "Circle" ? 80 : 0
    GridView {
    model: WidgetModel { id: widgetModel }
    delegate: widgetDelegate

    This is a GridView with one model?

    The dataset can come from an online feed, from XML (like Flickr/Facebook/Twitter or a personal database), or a simple ListModel type.

    Did you mean multiple models?

  • suppose you has a database table Persons(id,name,phone,address,JobTitle,etc) . Gridview has one model , and one model can display predefined data row , suppose I made the following query (SELECT ID,ADDRESS FROM PERSONS) ???? and in another time the query (SELECT ETC FROM PERSONS)??

  • Yes, I have done this a few times.

    Have a look at the Twitter app in the SDK that uses very similar 'SELECT' style commands via an XML Model.

    Alternatively, you can use a ListModel and sort it yourself.
    Remember, you can change the model at any time and you can have temporary models that hold all the information but are never used if you like.

  • Here's an example to demonstrate: SELECT "flagged" FROM name IN widgetmodel (pseudo sql query)
    Using a ListModel:

    @GridView {
    model: WidgetModel { id: widgetModel }
    delegate: widgetDelegate
    MouseArea {
    id: selectFlaggedFromName
    anchors.fill: parent
    onClicked: {
    for (var i = 0; i < widgetModel.count; i++)
    if (widgetModel.get(i).name != "flagged")

    Working fine here.

  • thank you xsacha I will review that and of course feed you back about?

  • assistant say:
    *QAbstractItemModel presents a hierarchy of tables, but the views currently provided by QML can only display list data. *

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