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

[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.