QTreeView not refresh correctly

[NicolasS]

Hi all,

In my application, I have a tree hierarchical structure FooTree that contains Foo* objects.
Each Foo object knows how many children it has and also its index in its parent's children table.

Now I'd like to display the FooTree in a QTreeView.
I've reimplemented my own QAbstractItemModel where each QModelIndex owns a Foo* (based on doc from http://doc.qt.io/qt-5/modelview.html)
For example, rowCount() and index() looks like this :

int FooModel::rowCount(QModelIndex & parent) int
{
	return static_cast<Foo*>(parent.internalPointer())->GetNumberOfChild();
}

QModelIndex FooModel::index(int row,int column,const QModelIndex &parent) const
{
	Foo* FooParent=NULL;
	if(!parent.isValid())
		FooParent = m_Root;
	else
		FooParent = static_cast<Foo*>(parent.internalPointer());

	Foo* FooChild = NULL;
	if(FooParent )
	{
		int nbChildren = FooParent->GetChildrenNumber();
		if( row >= 0 && row < nbChildren)
			FooChild = FooParent->GetChild(row);
	}

	if(FooChild)
		indexToReturn=createIndex( row, column, FooChild);

	return indexToReturn;
}

When I launch my QTreeView, it's ok, the view displays the existing FooTree correctly.

My problem is when I append Foo* Child to an existing Foo* Parent in my FooTree, I can't have the view to refresh correctly.

For the moment, once the Foo* has been added I call this method on the model :

void FooModel::FooHasBeenAdded( Foo* foo)
{
	QModelIndex parentIndex = IndexOf( foo->GetParent());	// Custom func to retrieve the index of a Foo*
	emit dataChanged( parentIndex, parentIndex);
}

I would expect that emitting dataChanged(parentIndex, parentIndex) would re-create all the indices under parentIndex (because rowCount(parentIndex) has changed) and then notify the view but it doesn't work.

Any ideas ? Is there something wrong with my code ?

[SGaist]

Hi and welcome to devnet,

You should also call the appropriate beginInsertRows and endInsertRows when you add data to your structure. That will trigger the proper update for the views

[NicolasS]

@SGaist Thanks for your advise, it works like well now.