QML - Retrieving index of delegate in DelegateModel - qt

Question

I have trouble retrieving the index of a delegate that is instantiated inside a DelegateModel for a ListView.
The minimal example as following:
LastProcedures.qml
ListModel {
ListElement {
procedure: "Liver Resection"
surgeon: "Prof. Dr. Joyride"
recent: true
}
...
}
main.qml
ListView {
id: list_lastProcedures
model: displayDelegateModel
}
DelegateModel {
id: displayDelegateModel
delegate: lastProceduresDelegate
model: LastProcedures {}
groups: [
DelegateModelGroup {
includeByDefault: false
name: "recent"
}
]
filterOnGroup: "recent"
Component.onCompleted: {
var rowCount = model.count;
items.remove(0,rowCount);
for( var i = 0;i < rowCount;i++ ) {
var entry = model.get(i);
// Only the recent three
if((entry.recent == true) && (items.count < 3)) {
items.insert(entry, "recent");
}
}
}
}
Component {
id: lastProceduresDelegate
Text{
text: model.index
}
}
The text index prints always -1. Without a DelegateModel it prints the index in the ListView. How can I access the correct index of the delegate in the Listview?

Answer 1

you can use "lastProceduresDelegate.DelegateModel.itemsIndex" instead of "model.index"
just like this:
Component {
id: lastProceduresDelegate
Text{
text: lastProceduresDelegate.DelegateModel.itemsIndex
}

Answer 2

I ended up with not removing all entries and adding them back to groups, but instead just remove unwanted entries. This ways the index stays valid.
If someone could explain this behavior further, that would be nice.
DelegateModel {
id: displayDelegateModel
delegate: lastProceduresDelegate
model: LastProcedures {}
groups: [
DelegateModelGroup {
includeByDefault: true
name: "recenttrue"
}
]
filterOnGroup: "recenttrue"
Component.onCompleted: {
for( var i = 0;i < items.count;i++ ) {
var entry = items.get(i).model;
// Only the recent
if((entry.recent != true)) {
items.removeGroups(i, 1, "recenttrue");
}
}
}
}

Answer 3

The DelegateModel has some hidden magic regarding groups (it's not very visible but it's here ). For each group you create, the DelegateModel attached property will receive two new properties: <group>Index and in<Group>.
In your case this means you will get the following properties: recentIndex and inRecent (or in your own answer: recenttrueIndex and inRecenttrue).
I think with what you want to do you should go the recenttrue route and draft the Component as follows:
Component {
id: lastProceduresDelegate
Text {
text: lastProceduresDelegate.DelegateModel.recenttrueIndex
}
}