QStandardItemModel's insertRow() did't make a grandchild item in QTreeView

[kichi]

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() ?

#include <QtGui/QApplication>
#include <QtCore/QModelIndex>
#include <QtGui/QStandardItem>
#include <QtGui/QStandardItemModel>
#include <QTreeView>
#include <QtDebug>
 
int main(int argc, char *argv[])
{
	QApplication application(argc, argv);
 
	QStandardItemModel	model;
	QTreeView			treeView;
	treeView.setModel(&model);
 
	// (Case 1)
//	QStandardItem* rootItem = model.invisibleRootItem();
//	rootItem->insertRow(0, new QStandardItem("Child Item"));
//	QStandardItem* childItem = rootItem->child(0, 0);
//	if (childItem)
//		childItem->insertRow(0, new QStandardItem("Grandchild Item"));
 
	// (Case 2)
	model.insertRow(0, new QStandardItem("Child Item"));
	QModelIndex childItemIndex = model.index(0, 0, QModelIndex());
	bool isSuccess = false;
	if (childItemIndex.isValid()) {
		isSuccess = model.insertRow(0, childItemIndex);	// make a grandchild, but the item does not appear
	}
	qDebug() << "isSuccess : " << isSuccess;	// true
 
	childItemIndex = model.index(0, 0, QModelIndex());
	qDebug() << "childItemIndex.isValid : " << childItemIndex.isValid();	// true
	QModelIndex grandchildItemIndex = model.index(0, 0, childItemIndex);
	qDebug() << "grandchildItemIndex.isValid() : " << grandchildItemIndex.isValid();	// false
 
	treeView.show();
 
	return application.exec();
}

#include <QtGui/QApplication>
#include <QtCore/QModelIndex>
#include <QtGui/QStandardItem>
#include <QtGui/QStandardItemModel>
#include <QTreeView>
#include <QtDebug>

int main(int argc, char *argv[])
{
	QApplication application(argc, argv);

	QStandardItemModel	model;
	QTreeView			treeView;
	treeView.setModel(&model);

	// (Case 1)
//	QStandardItem* rootItem = model.invisibleRootItem();
//	rootItem->insertRow(0, new QStandardItem("Child Item"));
//	QStandardItem* childItem = rootItem->child(0, 0);
//	if (childItem)
//		childItem->insertRow(0, new QStandardItem("Grandchild Item"));

	// (Case 2)
	model.insertRow(0, new QStandardItem("Child Item"));
	QModelIndex childItemIndex = model.index(0, 0, QModelIndex());
	bool isSuccess = false;
	if (childItemIndex.isValid()) {
		isSuccess = model.insertRow(0, childItemIndex);	// make a grandchild, but the item does not appear
	}
	qDebug() << "isSuccess : " << isSuccess;	// true

	childItemIndex = model.index(0, 0, QModelIndex());
	qDebug() << "childItemIndex.isValid : " << childItemIndex.isValid();	// true
	QModelIndex grandchildItemIndex = model.index(0, 0, childItemIndex);
	qDebug() << "grandchildItemIndex.isValid() : " << grandchildItemIndex.isValid();	// false

	treeView.show();

	return application.exec();
}

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I'm sorry in poor English.

[numbat]

You need to insert a column as well. The insertRow which takes a QStandardItem does this automatically.

if (childItemIndex.isValid()) {
		isSuccess = model.insertRow(0, childItemIndex);	// make a grandchild, but the item does not appear
		isSuccess = model.insertColumn(0, childItemIndex); // Need this...
	}

if (childItemIndex.isValid()) {
		isSuccess = model.insertRow(0, childItemIndex);	// make a grandchild, but the item does not appear
		isSuccess = model.insertColumn(0, childItemIndex); // Need this...
	}

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[kichi]

You need to insert a column as well. The insertRow which takes a QStandardItem does this automatically.

if (childItemIndex.isValid()) {
		isSuccess = model.insertRow(0, childItemIndex);	// make a grandchild, but the item does not appear
		isSuccess = model.insertColumn(0, childItemIndex); // Need this...
	}

if (childItemIndex.isValid()) {
		isSuccess = model.insertRow(0, childItemIndex);	// make a grandchild, but the item does not appear
		isSuccess = model.insertColumn(0, childItemIndex); // Need this...
	}

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Your advice has solved the problem.
Thank you very much.