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  1. Qt
  2. QTBUG-110980

ComponentBehavior: Bound and generic delegates don't mix well

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    • e9f650cad (dev), be884811d (dev)

      I wanted to create a custom ComboBox, following the customization example:

      import QtQuick.Controls

ComboBox {
    id: control
    delegate: MenuItem {
        width: ListView.view.width
        text: control.textRole ? (Array.isArray(control.model) ? modelData[control.textRole] : model[control.textRole]) : modelData
        highlighted: control.highlightedIndex === index
    } 
}

      This works with both a ListMode and a QVariantList exported from C++ as a model, but when I run this through the QML compiler, it tells me:

      Warning: IconComboBox.qml:7:15: Unqualified access [unqualified]
        text: control.textRole ? (Array.isArray(control.model) ? modelData[control.textRole] : model[control.textRole]) : modelData
              ^^^^^^^
Info: Set "pragma ComponentBehavior: Bound" in order to use IDs from outer components in nested components.

      Fair enough: I addde a pragma ComponentBehavior: Bound to this file and I also added the (now needed) required properties for index and modelData. Now the array / QVariantList based model works, but the ListModel based ComboBox complains at runtime:

      qml: QML Component: Cannot create delegate
qml: Required property modelData was not initialized (at qrc:/Mobile/IconComboBox.qml, 12)

      And I get an empty popup. if I require model instead of modelData, it's the other way around.

      Is there a better solution besides ignoring the qml compiler's complaint about the missing bound behavior pragma to write a generic delegate that can handle both model and modelData?

        For Gerrit Dashboard: QTBUG-110980
        # Subject Branch Project Status CR V
        461051,33 Models: Straighten out model and modelData properties dev qt/qtdeclarative Status: MERGED +2 0
        474438,3 Models: Fix condition for context object dev qt/qtdeclarative Status: MERGED +2 0

            ulherman Ulf Hermann
            rgriebl Robert Griebl
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