[Qt-interest] removeRows() crash.

[Ellen Kestrel]

Are you trying to use a filter implemented with a QSortFilterProxyModel?  I
had a crash with removeRows that was fixed when I removed the filter and
reimplemented it in a different class, although I was using a QTreeView and
not a QListView.  If you find out a better way to fix it, though, I would
be very interested in hearing it.

- EK

On Thu, Apr 23, 2009 at 11:51 AM, phil prentice <philp.cheer at talktalk.net>wrote:

> My code crashes when I delete an item from a class derived from QListView.
>  I
> realise that I am probably going to have to cut my code down to get any
> help
> on this..but I thought that I would pass it by you all first just in case
> you
> know immediately what this is.
>
> I have over-ridden the method
> QItemSelectionModel::SelectionFlags selectionCommand
>                ( const QModelIndex & index, const QEvent * event = 0 )
> const;
> in QListView.
>
> I need this to decide if an index is to be selected or not (the mouse
> position
> inside the item will determine this).
>
> I use the code:-
> bottomArrowModel.removeRows(m_modelItem.row(), 1, QModelIndex());
> to remove a row.  bottomArrowModel is the model attached to the view.
>
> Its defiantly the selectionCommand that is causing the crash.  I think what
> might be happening is that the QModelIndex is being removed by removeRows()
> and then the signal is getting through to the selectionCommand.  At that
> point the QModelIndex() is no longer valid.
>
> The end of the stack trace from the debugger shows:-
>
> /* CRASH!!!! */
> #0  0x0805bf1a in QEvent::type (this=0x0)
>    at /usr/local/Trolltech/Qt-4.2.1/include/QtCore/qcoreevent.h:221
> #1  0x0805b993 in BottomFacilityListView::selectionCommand (this=0x85119a0,
>    index=@0xbfb8f86c, event=0x0) at bottomFacilityListView.cpp:79
> #2  0x00affe8e in QAbstractItemView::setCurrentIndex (this=0x85119a0,
>    index=@0xbfb8f86c) at itemviews/qabstractitemview.cpp:767
> #3  0x00b00d80 in QAbstractItemView::rowsAboutToBeRemoved (this=0x85119a0,
>    parent=@0xbfb8ff2c, start=0, end=0) at
> itemviews/qabstractitemview.cpp:2570
> #4  0x00b13feb in QListView::rowsAboutToBeRemoved (this=0x85119a0,
>    parent=@0xbfb8ff2c, start=0, end=0) at itemviews/qlistview.cpp:762
> #5  0x00b006c7 in QAbstractItemView::qt_metacall (this=0x85119a0,
>    _c=QMetaObject::InvokeMetaMethod, _id=48, _a=0xbfb8fe8c)
>    at .moc/release-shared/moc_qabstractitemview.cpp:199
> #6  0x00bc6f68 in QListView::qt_metacall (this=0x85119a0,
>    _c=QMetaObject::InvokeMetaMethod, _id=48, _a=0xbfb8fe8c)
>    at .moc/release-shared/moc_qlistview.cpp:98
> #7  0x0805e728 in BottomFacilityListView::qt_metacall (this=0x85119a0,
>    _c=QMetaObject::InvokeMetaMethod, _id=48, _a=0xbfb8fe8c)
>    at moc_bottomFacilityListView.cpp:60
> #8  0x0053e327 in QMetaObject::activate (sender=0xbfb923dc,
>    from_signal_index=10, to_signal_index=10, argv=Variable "argv" is not
> available.
> ) at kernel/qobject.cpp:2909
> #9  0x0053e95a in QMetaObject::activate (sender=0xbfb923dc, m=0x5c5918,
>    local_signal_index=6, argv=0xbfb8fe8c) at kernel/qobject.cpp:2952
> #10 0x0055c0d9 in QAbstractItemModel::rowsAboutToBeRemoved
> (this=0xbfb923dc,
>    _t1=@0xbfb8ff2c, _t2=0, _t3=0)
>    at .moc/release-shared/moc_qabstractitemmodel.cpp:160
> #11 0x00527b3e in QAbstractItemModel::beginRemoveRows (this=0xbfb923dc,
>    parent=@0xbfb8ff2c, first=0, last=0) at
> kernel/qabstractitemmodel.cpp:2008
> #12 0x08059b6a in BottomArrowModel::removeRows (this=0xbfb923dc,
> position=0,
>    rows=1) at bottomArrowModel.cpp:118
> #13 0x080515c5 in QTdcwb::deleteFacility (this=0xbfb92328) at
> QTdcwb.cpp:473
> #14 0x0805debe in QTdcwb::qt_metacall (this=0xbfb92328,
>    _c=QMetaObject::InvokeMetaMethod, _id=19, _a=0xbfb9049c)
>    at moc_QTdcwb.cpp:111
> #15 0x0053e327 in QMetaObject::activate (sender=0x851d388,
>    from_signal_index=5, to_signal_index=6, argv=Variable "argv" is not
> available.
> ) at kernel/qobject.cpp:2909
> #16 0x0053e75f in QMetaObject::activate (sender=0x851d388, m=0xd16440,
>    from_local_signal_index=1, to_local_signal_index=2, argv=0xbfb9049c)
>    at kernel/qobject.cpp:2961
> #17 0x00788ae4 in QAction::triggered (this=0x851d388, _t1=false)
>    at .moc/release-shared/moc_qaction.cpp:203
> #18 0x0078973f in QAction::activate (this=0x851d388,
> event=QAction::Trigger)
>    at kernel/qaction.cpp:1068
> #19 0x00a6592b in QMenuPrivate::activateAction (this=0x850f440,
>    action=0x851d388, action_e=QAction::Trigger) at widgets/qmenu.cpp:749
> #20 0x00a66783 in QMenu::mouseReleaseEvent (this=0xbfb923b4, e=0xbfb90b24)
>    at widgets/qmenu.cpp:1826
> #21 0x007d0ce1 in QWidget::event (this=0xbfb923b4, event=0xbfb90b24)
>    at kernel/qwidget.cpp:5574
> #22 0x00a62642 in QMenu::event (this=0xbfb923b4, e=0xbfb90b24)
>    at widgets/qmenu.cpp:1894
>
> Any ideas???
>
> Meanwhile I will start cutting my code down.
>
> Thanks everyone
>
> Phil
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