How to get parent of selected item in TreeView?

[RavenS]

Hello, guys. At first, sorry for my bad english...

For my purposes I was created widget kinda "date picker", based on model/view architecture. Widget haves the next structure (for example):

2000
  January
    1
    2
    3
    ...
  February
    1
    2
    3
    ...
  Other months...
2001
  January
    1
    ...
2002
2003
...
etc

2000
  January
    1
    2
    3
    ...
  February
    1
    2
    3
    ...
  Other months...
2001
  January
    1
    ...
2002
2003
...
etc

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User can pick a date. Not just a day, he can also pick a month, or a year.
It's so easy to get data of the selected item, just

value = model->data(treeWidget->currentIndex(), Qt::DisplayRole);

value = model->data(treeWidget->currentIndex(), Qt::DisplayRole);

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but how to get the parent of the selected item? In case when user selected a month or a day, we need to know, for which year belongs this month (or for which year and month belongs this day).
So, I need help How to get data of the parent of the selected item?