Undo by saving the whole model-state not actions possible with QUndoStack?

[gde23]

Hi,

i have a project where there is a QAbstractItemModel that can be manipulated by some actions.
The changes to the model sometimes are a bit complicated, so it is hard to keep track of all the action and the opposite of them.
Therefore I think the easiest way to implement Undo / Redo would be to just save the model state to a stack each time something is changed and load the old model for undo.

The problem I see with this approach is, that for loading back the old model I also have to "undo" the beginInsertColumns() beginRemoveRows() begindeleteRows() and so on for the ItemView.

Is there maybe some example for such a case?

[VRonin]

Even if it might be quite inefficient, if you have control over the model, you can call beginResetModel/endResetModel to signal the complete change to the view

[gde23]

@VRonin: Thanks for the hint.
I got that approach working now, however every time I undo the whole treeView collapses.
Is there some Method to prevent this?