Accessing role values using an index in a model

[fcarney]

I have QAbstractListModel object I am working with in my qml Action:

    onTriggered: {
            console.log("TransferRight")

            var index = acqparamsmodel.item.currentIndex
            var model = acqparammodelproxy.sourceModel
            var qindex = model.index(index,0)
            console.log(qindex)
            var modulename = model.data(qindex, model.nameRole)
            var name = model.data(qindex, model.moduleNameRole)
            console.log(modulename, name)
        }

I can get the index and I can call the data method. However, I am unsure of how to get the role integer for the call to data. I have used Q_ENUM on the enum with all the roles. There is also a roleNames function that will map the enum values to text names. I have tried calling data() with a the roleNames string instead of an integer and that doesn't work either. Worse comes to worse I could set global properties when a selection is made and fill those with the name and modulename. However, I really would like to know how to do this via that data call. I assume there are default roles like Qt.DisplayRole or some such, but I have custom roles and role indexes.

How do I get the custom role names/integers in QML?

[fcarney]

This is very frustrating. When editing the QML I can auto-complete the NameRole and ModuleNameRole on the acq_params object. However, it will not get that value when printing to console:

    onTriggered: {
            console.log("TransferRight")

            var index = acqparamsmodel.item.currentIndex
            //var model = acqparammodelproxy.sourceModel
            console.log(acqparammodelproxy.sourceModel)
            console.log(acq_params)
            console.log(acq_params.NameRole)
            console.log(acq_params.ModuleNameRole)
            console.log(AcqParamModel.NameRole)
            console.log(AcqParamModel.ModuleNameRole)
            var model = acqparammodelproxy
            console.log(acqparammodelproxy.NameRole)
            console.log(acqparammodelproxy.ModuleNameRole)
            var qindex = model.index(index,0)
            console.log(qindex)
            var modulename = model.data(qindex, AcqParamModel.NameRole)
            var name = model.data(qindex, AcqParamModel.ModuleNameRole)
            console.log(modulename, name)
        }

Output:

qml: TransferRight
qml: AcqParamModel(0x55ef6e768c90)
qml: AcqParamModel(0x55ef6e768c90)
qml: undefined
qml: undefined
qml: 386
qml: 391
qml: undefined
qml: undefined
qml: QModelIndex(0,0,0x55ef75001c20,StreamPrinter::AcqParamModelProxy(0x55ef6e85a9b0))
qml: Position AVC Module

I did go in a define AcqParamModel using:

qmlRegisterType<AcqParamModel>("XMUIQml", 1, 0, "AcqParamModel");

So I can get the enum values that way. But that means I cannot write generic code that works with multiple model types. I have to know which model type my code is accessing. This is really cumbersome. Maybe just setting properties on selection would be more generic.

[kshegunov]

My knowledge of QML is almost non-existent, but can't you register the enum of AcqParamModel with qmlRegisterUncreatableType()? I think this is why it was invented.

PS: Or registering the enum of the class directly?

[fcarney]

I decided to go a different all QML route:

                       MouseArea {
                            anchors.fill: parent
                            onClicked: {
                                delegate.ListView.view.currentIndex = index
                                delegate.ListView.view.currentName = name
                                delegate.ListView.view.currentModuleName = modulename
                            }
                        }

This mousearea is inside my view delegate. I just have to make sure there is a selection. The other route via the data method just has too much boilerplate.

[fcarney]

Apparently you can access currentItem of the model. So if you set properties on that delegate then you can access them through the currentItem interface.

[GrecKo]

I've create a small lib related to your problem : https://github.com/oKcerG/QmlModelHelper

You can query the roleNames of an arbitrary model with model.ModelHelper.roles as a map property or model.ModelHelper.roleForName("roleName") returning an int.
There's also some convenience data method like model.ModelHelper.data(row, "roleName").