Question

I am trying to restrict selection of a tree to a particular column.

I am using delegates heavily to create custom per-item-per-column behaviors, editors, etc. I was hoping I could somehow do this from a delegate by blocking an event or something similar. The problem is, I think i would have to create an entirely custom solution that mimics extended selection.

However, after a lot of searching and very few examples, it sounds like I want a custom QItemSelectionModel on my tree view. Is this assumption correct?

How do I create a custom QItemSelectionModel that will use the Extended Selection Mode but allow me to ignore or revert a selection if not in a particular column. In other words, clicking on another column should not change the selection (should not select or deselect)

I know how to add the selection model once I have it. I am asking for help implementing the derived class (unless this can be done with a connected signal).

I am using Python, but would value any help.

Thank you,

[EDIT:] I found these similar questions:
http://lists.qt.nokia.com/pipermail/qt-interest/2010-September/027647.html

“Subclass QItemSelectionModel and reimplement both select methods to have the
behaviour you want. Just ignore the parts of ranges with column > 0.
…
Or maybe just reimplement flags() to make the item not selectable. I don’t
know if that will have any side effects.”

I tried reimplementing flags on my QTreeWidgetItem, but it never got called:

def flags(self, index):
    print index.column()
    return super(DDOutlinerBaseItem, self).flags(index)

Answer 1

The following adjustment should work, in theory.

The above solution could use two separate methods and @pyqtSlot decorators to disambiguate the overloaded method names:

@pyqtSlot(QModelIndex, QItemSelectionModel.SelectionFlags)
  def select(self, index, command):
    # ...

@pyqtSlot(QItemSelection, QItemSelectionModel.SelectionFlags)
  def select(self, selection, command):
    #...

This avoids the need to check for instances of certain classes in the method implementations.