This is a text-only version of the following page on https://raymii.org:
---
Title       : 	Loop over all Repeater items or Delegate's in Qml
Author      : 	Remy van Elst
Date        : 	09-02-2022
URL         : 	https://raymii.org/s/snippets/Loop_over_all_Repeater_items_or_Delegates_in_Qml.html
Format      : 	Markdown/HTML
---




This small snippet shows how to loop over all Repeater items in Qml and also over all Delegate items in Qml. There are sublte differences between the two.
I'm using this to update visual all items in a control, before syncing state to a networked backend, and if the backend actions fails, I undo the visual state change. The network backend could be slow, by keeping state locally and syncing in the background, the user can continue working.

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![demo program][1]

> A demo program that loops over both a `Repeater` and a `GridViews` `Delegates`


This is the `ListModel` i'm using, but it could also be a C++ `QAbstractListModel`.

    ListModel {
        id: exampleModel
        ListElement {
            name: "Apple"
            price: 0.50
        }
        ListElement {
            name: "Orange"
            price: 2.00
        }
        ListElement {
            name: "Banana"
            price: 1.50
        }
    }

This is the `GridLayout` with a `Repeater`:

    GridLayout {
      id: exampleLayout
      Repeater {
          id: exampleRepeater
          model: exampleModel
          delegate: Button {
              text: model.name + ": " + model.price
              readonly property var price: model.price
          }
      }
}

This is the snippet to loop over all items in that `Repeater` and acces their properties:

    function logRepeaterItems(repeaterItem) {
        for (var i = 0; i < repeaterItem.count; i++) {
            console.log("repeater price: " + repeaterItem.itemAt(i).price)
            console.log("repeater text: " + repeaterItem.itemAt(i).text)
        }
    }

This is the `GridView` with `Delegates`:

    GridView {
      id: exampleView
      model: exampleModel
      delegate: Button {
          text: model.name + ": " + model.price
          readonly property var price: model.price
      }
    }

This is the snippet to loop over all `Delegates`:

    // warning: its better to loop over the actual model than the delegates.
    // Only visible delegates are guaranteed to be in this loop.
    function logDelegateItems(delegateItem) {
        for (var child in delegateItem.contentItem.children) {
            var item = delegateItem.contentItem.children[child]
            console.log("delegate price: " + item.price)
            console.log("delegate text: " + item.text)
        }
    }


If you're looping over all delegates, think twice. It's better to loop
over the backing `model`, since not all delegates are always available. 
If they're not visible, they might not be there.


### Demo Qml Program

Here is the demo program showcasing both methods:


**main.qml**

    import QtQuick 2.15
    import QtQuick.Window 2.15
    import QtQuick.Layouts 1.3
    import QtQuick.Controls 2.12
    
    Window {
        width: 640
        height: 480
        visible: true
        title: qsTr("Loop over model/repeater example")
    
        function listProperties(item) {
            var properties = ""
            for (var p in item)
                properties += (p + ": " + item[p] + "\n")
            return properties
        }
    
        // warning: its better to loop over the actual model than the delegates.
        // Only visible delegates are guaranteed to be in this loop.
        function logDelegateItems(delegateItem) {
            for (var child in delegateItem.contentItem.children) {
                var item = delegateItem.contentItem.children[child]
                console.log("delegate price: " + item.price)
                console.log("delegate text: " + item.text)
            }
        }
    
        function logRepeaterItems(repeaterItem) {
            for (var i = 0; i < repeaterItem.count; i++) {
                console.log("repeater price: " + repeaterItem.itemAt(i).price)
                console.log("repeater text: " + repeaterItem.itemAt(i).text)
            }
        }
    
        ListModel {
            id: exampleModel
            ListElement {
                name: "Apple"
                price: 0.50
            }
            ListElement {
                name: "Orange"
                price: 2.00
            }
            ListElement {
                name: "Banana"
                price: 1.50
            }
        }
    
        Button {
            id: loopButton
            anchors.top: parent.top
            anchors.left: parent.left
            anchors.margins: 10
            text: "Loop over GridLayout Repeater"
            onClicked: logRepeaterItems(exampleRepeater)
        }
    
        Button {
            id: loopViewButton
            anchors.top: parent.top
            anchors.left: loopButton.right
            anchors.margins: 10
            text: "Loop over GridView Delegates"
            onClicked: logDelegateItems(exampleView)
        }
    
        Text {
            id: gridlayouttext
            text: "GridLayout with Repeater"
            anchors.top: loopButton.bottom
            anchors.margins: 5
            anchors.left: parent.left
        }
    
        GridLayout {
            anchors.top: gridlayouttext.bottom
            anchors.left: parent.left
            anchors.margins: 5
            id: exampleLayout
            height: 100
            columns: 3
            columnSpacing: 5
            Repeater {
                id: exampleRepeater
                model: exampleModel
                delegate: Button {
                    text: model.name + ": " + model.price
                    readonly property var price: model.price
                }
            }
        }
    
        Text {
            id: gridviewtext
            text: "GridView with Delegate and model"
            anchors.top: exampleLayout.bottom
            anchors.margins: 5
            anchors.left: parent.left
        }
    
        GridView {
            anchors.top: gridviewtext.bottom
            anchors.left: parent.left
            anchors.margins: 5
            height: 200
            width: 300
            id: exampleView
            model: exampleModel
            delegate: Button {
                text: model.name + ": " + model.price
                readonly property var price: model.price
            }
        }
    }




**main.cpp**

    #include <QGuiApplication>
    #include <QQmlApplicationEngine>
    
    
    int main(int argc, char *argv[])
    {
    #if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
        QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
    #endif
    
        QGuiApplication app(argc, argv);
    
        QQmlApplicationEngine engine;
        const QUrl url(QStringLiteral("qrc:/main.qml"));
        QObject::connect(&engine, &QQmlApplicationEngine::objectCreated,
                         &app, [url](QObject *obj, const QUrl &objUrl) {
            if (!obj && url == objUrl)
                QCoreApplication::exit(-1);
        }, Qt::QueuedConnection);
        engine.load(url);
    
        return app.exec();
    }




[1]: /s/inc/img/qml_loop_over_delegates.png

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