Problem while deleting item in QTreeView

Hello,

I have a QTreeView with some simple custom items in it.
I also have a simple CustomTreeModel derived from QAbstractItemModel.

I have a QMenu setup so I can click on the items in the tree and press "Delete" which is supposed to delete the current selected item and all its children.

this is the code that I use to delete the items, it works but only for the children, If I call deleteLater() on the current selected item the app crashes.

Code:

---

void MyCustomItem::OnDelete()
{
      const QObjectList& childrenList = children();
      int numChildren = childrenList.size();
      for(unsigned int i = 0; i < numChildren; ++i)
      {
               QObject* pChildObj = childrenList[0];
	 MyCustomItem* pChild = qobject_cast<MyCustomItem*>(pChildObj);
               if(pChild)
	 {
	          pChild->OnDelete();
                        delete pChild;
	  }
       }
 
        QTreeView* pTV = mpAssociatedTreeView;  //for simplicity assume that every object knows the treeview it is in
        pTV->clearSelection();
        pTV->reset();
 
 
        deleteLater();    <== if I comment out this line it doesn't crash and all the children objects in the tree are gone
}

---

I have seen so many posts about using removeRows in the model rather than actually calling delete on the objects, but I fail to understand how these are exactly working.

this is the crash callstack that I get when using deleteLater() on my currently selected item in the tree.

Code:

---

>	Qt5Cored.dll!QObject::parent() Line 386	C++
 	MyApp.exe!CustomTreeModel::parent(const QModelIndex & index={...}) Line 109	C++
 	Qt5Cored.dll!QModelIndex::parent() Line 462	C++
 	Qt5Widgetsd.dll!QTreeView::drawRow(QPainter * painter=0x000000000018a9a8, const QStyleOptionViewItem & option={...}, const QModelIndex & index={...}) Line 1545	C++
 	Qt5Widgetsd.dll!QTreeView::drawTree(QPainter * painter=0x000000000018a9a8, const QRegion & region={...}) Line 1456	C++
 	Qt5Widgetsd.dll!QTreeView::paintEvent(QPaintEvent * event=0x000000000018bca0) Line 1282	C++
 	Qt5Widgetsd.dll!QWidget::event(QEvent * event=0x000000000018bca0) Line 8030	C++
 	Qt5Widgetsd.dll!QFrame::event(QEvent * e=0x000000000018bca0) Line 534	C++
 	Qt5Widgetsd.dll!QAbstractScrollArea::viewportEvent(QEvent * e=0x000000000018bca0) Line 1163	C++
 	Qt5Widgetsd.dll!QAbstractItemView::viewportEvent(QEvent * event=0x000000000018bca0) Line 1680	C++
 	Qt5Widgetsd.dll!QTreeView::viewportEvent(QEvent * event=0x000000000018bca0) Line 1263	C++
 	Qt5Widgetsd.dll!QAbstractScrollAreaPrivate::viewportEvent(QEvent * event=0x000000000018bca0) Line 105	C++
 	Qt5Widgetsd.dll!QAbstractScrollAreaFilter::eventFilter(QObject * o=0x0000000008993450, QEvent * e=0x000000000018bca0) Line 121	C++
 	Qt5Cored.dll!QCoreApplicationPrivate::sendThroughObjectEventFilters(QObject * receiver=0x0000000008993450, QEvent * event=0x000000000018bca0) Line 967	C++
 	Qt5Widgetsd.dll!QApplicationPrivate::notify_helper(QObject * receiver=0x0000000008993450, QEvent * e=0x000000000018bca0) Line 3451	C++
 	Qt5Widgetsd.dll!QApplication::notify(QObject * receiver=0x0000000008993450, QEvent * e=0x000000000018bca0) Line 3420	C++
 	Qt5Cored.dll!QCoreApplication::notifyInternal(QObject * receiver=0x0000000008993450, QEvent * event=0x000000000018bca0) Line 871	C++
 	Qt5Cored.dll!QCoreApplication::sendSpontaneousEvent(QObject * receiver=0x0000000008993450, QEvent * event=0x000000000018bca0) Line 235	C++
 	Qt5Widgetsd.dll!QWidgetPrivate::drawWidget(QPaintDevice * pdev=0x0000000008949888, const QRegion & rgn={...}, const QPoint & offset={...}, int flags=4, QPainter * sharedPainter=0x0000000000000000, QWidgetBackingStore * backingStore=0x0000000008b1f1c0) Line 5133	C++
 	Qt5Widgetsd.dll!QWidgetPrivate::paintSiblingsRecursive(QPaintDevice * pdev=0x0000000008949888, const QList<QObject *> & siblings={...}, int index=0, const QRegion & rgn={...}, const QPoint & offset={...}, int flags=4, QPainter * sharedPainter=0x0000000000000000, QWidgetBackingStore * backingStore=0x0000000008b1f1c0) Line 5325	C++
 	Qt5Widgetsd.dll!QWidgetPrivate::paintSiblingsRecursive(QPaintDevice * pdev=0x0000000008949888, const QList<QObject *> & siblings={...}, int index=2, const QRegion & rgn={...}, const QPoint & offset={...}, int flags=4, QPainter * sharedPainter=0x0000000000000000, QWidgetBackingStore * backingStore=0x0000000008b1f1c0) Line 5312	C++
 	Qt5Widgetsd.dll!QWidgetPrivate::drawWidget(QPaintDevice * pdev=0x0000000008949888, const QRegion & rgn={...}, const QPoint & offset={...}, int flags=4, QPainter * sharedPainter=0x0000000000000000, QWidgetBackingStore * backingStore=0x0000000008b1f1c0) Line 5183	C++
 	Qt5Widgetsd.dll!QWidgetPrivate::paintSiblingsRecursive(QPaintDevice * pdev=0x0000000008949888, const QList<QObject *> & siblings={...}, int index=0, const QRegion & rgn={...}, const QPoint & offset={...}, int flags=4, QPainter * sharedPainter=0x0000000000000000, QWidgetBackingStore * backingStore=0x0000000008b1f1c0) Line 5325	C++
 	Qt5Widgetsd.dll!QWidgetPrivate::drawWidget(QPaintDevice * pdev=0x0000000008949888, const QRegion & rgn={...}, const QPoint & offset={...}, int flags=4, QPainter * sharedPainter=0x0000000000000000, QWidgetBackingStore * backingStore=0x0000000008b1f1c0) Line 5183	C++
 	Qt5Widgetsd.dll!QWidgetPrivate::paintSiblingsRecursive(QPaintDevice * pdev=0x0000000008949888, const QList<QObject *> & siblings={...}, int index=4, const QRegion & rgn={...}, const QPoint & offset={...}, int flags=4, QPainter * sharedPainter=0x0000000000000000, QWidgetBackingStore * backingStore=0x0000000008b1f1c0) Line 5325	C++
 	Qt5Widgetsd.dll!QWidgetPrivate::drawWidget(QPaintDevice * pdev=0x0000000008949888, const QRegion & rgn={...}, const QPoint & offset={...}, int flags=4, QPainter * sharedPainter=0x0000000000000000, QWidgetBackingStore * backingStore=0x0000000008b1f1c0) Line 5183	C++
 	Qt5Widgetsd.dll!QWidgetPrivate::paintSiblingsRecursive(QPaintDevice * pdev=0x0000000008949888, const QList<QObject *> & siblings={...}, int index=1, const QRegion & rgn={...}, const QPoint & offset={...}, int flags=4, QPainter * sharedPainter=0x0000000000000000, QWidgetBackingStore * backingStore=0x0000000008b1f1c0) Line 5325	C++
 	Qt5Widgetsd.dll!QWidgetPrivate::drawWidget(QPaintDevice * pdev=0x0000000008949888, const QRegion & rgn={...}, const QPoint & offset={...}, int flags=4, QPainter * sharedPainter=0x0000000000000000, QWidgetBackingStore * backingStore=0x0000000008b1f1c0) Line 5183	C++
 	Qt5Widgetsd.dll!QWidgetPrivate::paintSiblingsRecursive(QPaintDevice * pdev=0x0000000008949888, const QList<QObject *> & siblings={...}, int index=0, const QRegion & rgn={...}, const QPoint & offset={...}, int flags=4, QPainter * sharedPainter=0x0000000000000000, QWidgetBackingStore * backingStore=0x0000000008b1f1c0) Line 5325	C++
 	Qt5Widgetsd.dll!QWidgetPrivate::drawWidget(QPaintDevice * pdev=0x0000000008949888, const QRegion & rgn={...}, const QPoint & offset={...}, int flags=4, QPainter * sharedPainter=0x0000000000000000, QWidgetBackingStore * backingStore=0x0000000008b1f1c0) Line 5183	C++
 	Qt5Widgetsd.dll!QWidgetPrivate::paintSiblingsRecursive(QPaintDevice * pdev=0x0000000008949888, const QList<QObject *> & siblings={...}, int index=0, const QRegion & rgn={...}, const QPoint & offset={...}, int flags=4, QPainter * sharedPainter=0x0000000000000000, QWidgetBackingStore * backingStore=0x0000000008b1f1c0) Line 5325	C++
 	Qt5Widgetsd.dll!QWidgetPrivate::drawWidget(QPaintDevice * pdev=0x0000000008949888, const QRegion & rgn={...}, const QPoint & offset={...}, int flags=4, QPainter * sharedPainter=0x0000000000000000, QWidgetBackingStore * backingStore=0x0000000008b1f1c0) Line 5183	C++
 	Qt5Widgetsd.dll!QWidgetPrivate::paintSiblingsRecursive(QPaintDevice * pdev=0x0000000008949888, const QList<QObject *> & siblings={...}, int index=9, const QRegion & rgn={...}, const QPoint & offset={...}, int flags=4, QPainter * sharedPainter=0x0000000000000000, QWidgetBackingStore * backingStore=0x0000000008b1f1c0) Line 5325	C++
 	Qt5Widgetsd.dll!QWidgetPrivate::drawWidget(QPaintDevice * pdev=0x0000000008949888, const QRegion & rgn={...}, const QPoint & offset={...}, int flags=5, QPainter * sharedPainter=0x0000000000000000, QWidgetBackingStore * backingStore=0x0000000008b1f1c0) Line 5183	C++
 	Qt5Widgetsd.dll!QWidgetBackingStore::sync() Line 1093	C++

---

it looks to me as if the qtreeview is still drawing the items but I have just deleted one. In fact

Code:

---

QModelIndex CustomTreeModel::parent(const QModelIndex &index) const
{
	if( !index.isValid() )
		return QModelIndex();
 
	QObject *indexObject = static_cast<QObject*>( index.internalPointer() );
	QObject *parentObject = indexObject->parent();          //the indexObject  is garbage at this point
 
	if( parentObject == m_root )
		return QModelIndex();
 
	QObject *grandParentObject = parentObject->parent();
 
	return createIndex( grandParentObject->children().indexOf( parentObject ), 0, parentObject );
}

---

one more thing I can say is that from looking at my CustomTreeModel (where I store the root of my tree) I can tell that the root is the only object left after I delete its only child (with 1 subchild).

this is the tree before calling pItemA->OnDelete()

root (invisible)
+--- ItemA
+-------- ItemA0



anyone has some suggestions ? I tried look at the Qt examples as well to understand how to create a clean QTreeView but its not very clear to me.

any help is appreciated.

Use beginRemoveRows() and endRemoveRows() in the CustomTreeModel.
example

Code:

---

beginRemoveRows()
//Here delete the item/items from internal contaner.
endRemoveRows()
//Now tree view will not access the deleted item.

---