Get QModelIndex from Treeview rowDelegate

[p3c0]

@illunara Afaik getting data through model instead of delegate is the recommended way. Didn't it work through model ?

[illunara]

@p3c0 The only thing i have frow rowDelegate is row number, i can't get model data just with that (Except on the top level)

[p3c0]

@illunara Why not ? For eg. following code gives you QModelIndex's of all top level item.

var top = [];
for (var i = 0; i < myModel.rowCount(); ++i ) {
    top[i] = myModel.index( i, 0 );
}
console.log(top)

Once you get the top level you can get their children. It would be better if you do the same on the C++ side as I think getting children should be lot more easier there.

[illunara]

@p3c0 Well, because i want to draw the row's color base on item data's attribute. Say :
I have a field in the item which tell me if data had been changed or not, if yes, then set the row's color to blue. But i can't access to its data with only row number of rowDelegate

If i have QModelIndex i can do it normally with

   static_cast<Class*>(index.internalPointer()).getData(....)

Here my my rowDelegate code for TableView btw
...

 rowDelegate : Rectangle {
    color : (model.get(styleData.row, "DataChanged")  ? "#000000" : "#ffffff"
}

...

[p3c0]

@illunara Try making use of dataChanged signal. I hope you do that in model when you update the data. Then on QML side you can use Connections to listen to the signal keeping the model as target. When the signal is emitted the corresponding handler will be invoked which will return the model indexes which were updated. Once you get those indexes getting its value(data) should be easier IMO. I haven't tried it myself but seems workable.

[illunara]

@p3c0 Still, without access to the rowDelegate component, even if i have modelIndex of the item, nothing can be done.

And i think the rowDelegate invoke got invoked before emit dataChanged signal.
Maybe we should left it at here, i will think another way to handle this.
Thank you so much for helping me :)

[p3c0]

@illunara I think it can be done. Once you get the model index you just have to request the new data (since binding to rolename doesn't work). Something like this inside rowDelegate :

Connections {
    target: dataModel
    onDataChanged: {
        var index = topLeft
        update(index)
    }
}

function update(modelIndex) {
    var value = dataModel.data(modelIndex, dataModel.getRoleKey("SomeRole"))
    //SomeRole is the role defined model which reflects the data you require. 
    color = value
}

getRoleKey function is explained here.

[illunara]

@p3c0 Nice idea, but this approach have one problem
Whenever a dataChanged emit, every row will get updated. Which mean, we need data to compare and find out which row, that data belong to.

Only thing we have is styleData.row and its not enough for a complicate model. And unfortunately, we can't access to it when call the update() method either. The value is undefined (ofc, I put it inside rowDelegate)

[p3c0]

@illunara

Whenever a dataChanged emit, every row will get updated. Which mean, we need data to compare and find out which row, that data belong to.

Yes. You just need to add a simple condition before calling function update

var index = topLeft
if(index.row===styleData.row)
   update(index)

[illunara]

@p3c0
Root
| ---- Item A // Row 1
|#####|---------- Item B // Row2 (Expected Row 1)
|#####|---------- Item C // Row3 (Expected Row 2)
| ---- Item D //Row4 (Exoected Row 2)

styleData.row is relative only to rootItem. That's why this method will not work