I agree with the doc for the "first level" of properties, but is it also by design even if the required properties are in a sub item, as in my 2nd example (where the delegate itself doesn't have any required properties)? It is this case that seems a bug to me.
-- Benjamin > Le 13 mai 2022 à 14:42, Even Kristoffersen <even.kristoffer...@semcon.com> a > écrit : > > This behavior surprised me first time I encountered it as well, but it is not > a bug as the behavior is documented here: > > https://doc.qt.io/qt-5/qtquick-modelviewsdata-modelview.html > <https://doc.qt.io/qt-5/qtquick-modelviewsdata-modelview.html> > {required properties} can be used. If a delegate contains required > properties, the named roles are not provided. Instead, the QML engine will > check if the name of a required property matches that of a model role. If so, > that property will be bound to the corresponding value from the model. > > So if you have any “required” keyword in the delegate, the model won’t be > attached. > > > Even Kristoffersen > even.kristoffer...@semcon.com <mailto:even.kristoffer...@semcon.com> > +4795223753 > > From: Interest <interest-boun...@qt-project.org> On Behalf Of Benjamin B > (BBenj) > Sent: fredag 13. mai 2022 14:11 > To: interest@qt-project.org > Subject: [Interest] QML required property in view delegate - bug? > > Hello, > > I encountered a "friction point", and I think a bug, in QML with the > "required" attribute for properties, when used in a view delegate. > Here is an example hacked from the docs : > > Item { > ListModel { > id: myModel > ListElement { type: "Dog"; age: 8; noise: "meow" } > ListElement { type: "Cat"; age: 5; noise: "woof" } > } > > component SomeDelegate: Item { > required property int age > property string text > } > > Repeater { > model: myModel > delegate: SomeDelegate { > text: model.noise > } > } > } > > Which raises the error "ReferenceError: model is not defined", as documented. > Is there a way around this? > I feel like this should be valid, as the delegate may not exactly match the > model in every case. I would prefer not having this "auto-bind" feature and > keep access to model/modelData/index. > > But then, if I can't modify SomeDelegate (or want to keep the required > property), how do I do? > I tried various things to encapsulate SomeDelegate into something else, but I > always get the same error. As soon as some child item has a required > property, "model" is not available anymore. This is a bug, right? > > The following doesn't work for example (same error): > > Item { > ListModel { > id: myModel > ListElement { type: "Dog"; age: 8; noise: "meow" } > ListElement { type: "Cat"; age: 5; noise: "woof" } > } > > component SomeDelegate: Item { > required property int age > property string text > } > > component AnotherDelegate: Item { > property int _age > property string _text > > SomeDelegate { > age: 0 > text: "" > } > } > > Repeater { > model: myModel > delegate: AnotherDelegate { > _age: model.age > _text: model.noise > } > } > } > > (I'm testing with qml/qmlscene, Qt 6.3.0, Qt 5.15.2) > > > Thank you, > > -- > Benjamin > > > > > When you communicate with us or otherwise interact with Semcon, we will > process personal data that you provide to us or we collect about you, please > read more in our Privacy Policy <https://semcon.com/data-privacy-policy/>.
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