How to call a method of a QModelIndex object from QML?

[drhm]

In the following example index is an object of the QModelIndex class:

var s = index.sibling(0, 0)

The execution leads to the following error:

TypeError: Property 'sibling' of object QModelIndex(0,0,0x286a3e0,FileSystemModel(0x19bc150)) is not a function

The same error type occurs with the following line:

var s = index.row()

But using row as a property like in the following line works:

var s = index.row

So, what's going wrong here? How can I call a method of a QModelIndex object in a QML file?