Cannot access model index of ObjectModel inside delegate ?

[Diracsbracket]

Hi,
I have an ObjectModel which I dynamically populate with model delegates with Item as root element.

The documentation states that

ObjectModel.index : int
This attached property holds the index of this delegate's item within the model.
It is attached to each instance of the delegate.

However I cannot seem to get this index property. I have tried

Item {
     id: delegateItem
     ...
     MouseArea {
        anchors.fill: parent

        onClicked: {
            console.debug("Pressed: " + delegateItem.ObjectModel.index)
       }
    }    
}

But this gives the error

TypeError: Cannot read property 'index' of undefined

Of course, I have also tried to access index directly, as I would when using e.g. a ListModel, but that also does not work.

Furthermore, the following example always returns -1 when the delegate is pressed:

    ObjectModel {
        id: itemModel

        Rectangle {
            height: 30; width: 80; color: "red"
            MouseArea {
                anchors.fill: parent
                onClicked : console.debug(ObjectModel.index)
            }
        }

        Rectangle {
            height: 30; width: 80; color: "green"
            MouseArea {
                anchors.fill: parent
                onClicked : console.debug(ObjectModel.index)
            }
        }

        Rectangle {
            height: 30; width: 80; color: "blue"
            MouseArea {
                anchors.fill: parent
                onClicked : console.debug(ObjectModel.index)
            }
        }
    }

    ListView {
        anchors.fill: parent
        model: itemModel
    }

Any ideas?

[Diracsbracket]

Thanks to @jonB who got me thinking a bit more, I finally got it to work by adding the following import:

import QtQml.Models 2.10 as QM2

and then using:

console.debug("Pressed: " + delegateItem.QM2.ObjectModel.index)

Although I never declare an ObjectModel element inside the current QML file scope, I apparently needed to do the import anyway because I try to access the attached property ObjectModel.index. Without the import, ObjectModel is not defined.

Furthermore, I needed to use some import qualifier (here QM2) because otherwise, Qt Creator underlines the field names of a ListModel I have in the same QML file as having Invalid property name:

Note how this qualifier also needs to be used when accessing the attached property delegateItem.QM2.ObjectModel.index...

[JonB]

@Diracsbracket

console.debug("Pressed: " + delegateItem.ObjectModel.index)

TypeError: Cannot read property 'index' of undefined

This means that ObjectModel is undefined, not index.

[Diracsbracket]

@JonB said in Cannot access model index of ObjectModel inside delegate ?:

This means that ObjectModel is undefined, not index

Sure. But how can it be? I invoke the debug statement inside the delegate, upon a click (and therefore the delegate is instantiated). Furthermore, the delegate is appended to the ObjectModel, and the delegate is shown correctly inside the view. But when I click it, it gives the above error. How then should I access that attached property within the delegate?

[Diracsbracket]

Thanks to @jonB who got me thinking a bit more, I finally got it to work by adding the following import:

import QtQml.Models 2.10 as QM2

and then using:

console.debug("Pressed: " + delegateItem.QM2.ObjectModel.index)

Although I never declare an ObjectModel element inside the current QML file scope, I apparently needed to do the import anyway because I try to access the attached property ObjectModel.index. Without the import, ObjectModel is not defined.

Furthermore, I needed to use some import qualifier (here QM2) because otherwise, Qt Creator underlines the field names of a ListModel I have in the same QML file as having Invalid property name:

Note how this qualifier also needs to be used when accessing the attached property delegateItem.QM2.ObjectModel.index...

[JonB]

@Diracsbracket
This is why I find JavaScript allowing you to write

something.anythingITypeInIncludingMisspellings ...

is scarily dangerous :)