When I intended to write a small code using QTreeView and QStandardItemModel.
I encountered a problem.

When I made a grandchild item, using QStandardItemModel::insertRow(int row, const QModelIndex & parent = QModelIndex()),
the item did not appeared in the tree view.

In the following code, Case1 worked good.
But, contrary to my expectation, Case2 did not work.

Is it correct to make a grandchild item, using QStandardItemModel::insertRow() ?

Qt Code: 
  1. #include <QtGui/QApplication>
  2. #include <QtCore/QModelIndex>
  3. #include <QtGui/QStandardItem>
  4. #include <QtGui/QStandardItemModel>
  5. #include <QTreeView>
  6. #include <QtDebug>
  7.  
  8. int main(int argc, char *argv[])
  9. {
  10. 	QApplication application(argc, argv);
  11.  
  13. 	QTreeView			treeView;
  14. 	treeView.setModel(&model);
  15.  
  16. 	// (Case 1)
  17. //	QStandardItem* rootItem = model.invisibleRootItem();
  18. //	rootItem->insertRow(0, new QStandardItem("Child Item"));
  19. //	QStandardItem* childItem = rootItem->child(0, 0);
  20. //	if (childItem)
  21. //		childItem->insertRow(0, new QStandardItem("Grandchild Item"));
  22.  
  23. 	// (Case 2)
  24. 	model.insertRow(0, new QStandardItem("Child Item"));
  25. 	QModelIndex childItemIndex = model.index(0, 0, QModelIndex());
  26. 	bool isSuccess = false;
  27. 	if (childItemIndex.isValid()) {
  28. 		isSuccess = model.insertRow(0, childItemIndex);	// make a grandchild, but the item does not appear
  29. 	}
  30. 	qDebug() << "isSuccess : " << isSuccess;	// true
  31.  
  32. 	childItemIndex = model.index(0, 0, QModelIndex());
  33. 	qDebug() << "childItemIndex.isValid : " << childItemIndex.isValid();	// true
  34. 	QModelIndex grandchildItemIndex = model.index(0, 0, childItemIndex);
  35. 	qDebug() << "grandchildItemIndex.isValid() : " << grandchildItemIndex.isValid();	// false
  36.  
  37. 	treeView.show();
  38.  
  39. 	return application.exec();
  40. }
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I'm sorry in poor English.