QAbstractItemModel::endMoveRows: Invalid index

Diracsbracket

Hi,
To move a row of a QTreeView up or down with a button click, I have adapted the code from here to this code, which I reproduce here for convenience:

bool StandardItemModel::move(int from, bool isUp)
{
    //range checking etc.
    const int numRows = rowCount();

    if (from<0 || from>=numRows || (from==0 && isUp) || (from==numRows-1 && !isUp))
        return false;

    const int to = isUp ? from - 1: from + 1;

    //See documentation
    //http://doc.qt.io/qt-5/qabstractitemmodel.html#beginMoveRows
    //on why this is needed?
    const int toSignal = isUp ? to : to + 1;

    if (!beginMoveRows(QModelIndex(), from, from, QModelIndex(), toSignal))
        return false;

    blockSignals(true);
    QList<QStandardItem*> fromRow = takeRow(from); //this also removes it from the model!
    insertRow(to, fromRow); //but the actual insertion must be done using to, not toSignal!
    blockSignals(false);

    endMoveRows();

    return true;
}
Note that there is no removeRow(from) in the adapted code, as takeRow(from) seems to already take care of that.
In a dialog, I have Move Up and Move Down buttons that call the following dialog method:

void changeOrderDialog::moveCurrentRow(bool isUp)
{
    const QModelIndex index = ui->treeView->currentIndex();

    if (index.isValid())
    {
        StandardItemModel* model = qobject_cast<StandardItemModel*>(ui->treeView->model());
        const int row = index.row();

        if (model->move(row, isUp))
        {
            const QModelIndex newIndex = model->index(isUp ? row-1 : row+1, 0);
            ui->treeView->setCurrentIndex(newIndex);
        }
    }
}

Although the moves up and down + boundary conditions seem to work correctly, I get the following debugger messages (one triplet per up/down move, probably because I have 3 columns per row):

//Error on the moveUp (to lower row index):
QAbstractItemModel::endMoveRows:  Invalid index ( -2 , -1 ) in model StandardItemModel(0x779ad90)
QAbstractItemModel::endMoveRows:  Invalid index ( -2 , -1 ) in model StandardItemModel(0x779ad90)
QAbstractItemModel::endMoveRows:  Invalid index ( -2 , -1 ) in model StandardItemModel(0x779ad90)

//Error on the moveDown (to higher row index):
QAbstractItemModel::endMoveRows:  Invalid index ( 0 , -1 ) in model StandardItemModel(0x779ad90)
QAbstractItemModel::endMoveRows:  Invalid index ( 0 , -1 ) in model StandardItemModel(0x779ad90)
QAbstractItemModel::endMoveRows:  Invalid index ( 0 , -1 ) in model StandardItemModel(0x779ad90)

What do I need to do to avoid these messages?

proman

bool StandardItemModel::move(int from, bool isUp)
{
//range checking etc.
const int numRows = rowCount();

if (from<0 || from>=numRows || (from==0 && isUp) || (from==numRows-1 && !isUp))
    return false;

const int to = isUp ? from - 1: from + 1;

//See documentation
//http://doc.qt.io/qt-5/qabstractitemmodel.html#beginMoveRows
//on why this is needed?
const int toSignal = isUp ? to : to + 1;

if (!beginMoveRows(QModelIndex(), from, from, QModelIndex(), toSignal))
    return false;

blockSignals(true);
QList<QStandardItem*> fromRow = takeRow(from); //this also removes it from the model!

//add this 
beginInsertRows(QModelIndex(),from,toSignal);

insertRow(to, fromRow); //but the actual insertion must be done using to, not toSignal!
blockSignals(false);

endMoveRows();

return true;

}

it`s work for me.

Diracsbracket

@proman said in QAbstractItemModel::endMoveRows: Invalid index:

//add this
beginInsertRows(QModelIndex(),from,toSignal);

@proman, many thanks for your reply, and apologies for this late reaction. I did not recall seeing a notification about your post in my Qt notifications list and just happened to stumble on this old post of mine by accident.

Your addition works, I no longer have the debugger messages. Thanks again!

Diracsbracket

The problem I mentioned in my post above and in the reference therein to another post of mine was solved graciously by @proman.

He mentioned that I should add

beginInsertRows(QModelIndex(),from,toSignal);

before doing

insertRow(to, fromRow);

This avoids the debugger error messages.

UPDATE:
then line should actually be:

beginInsertRows(QModelIndex(),toSignal,toSignal);

otherwise, you'll get ASSERT error messages when moving up because last<first.