How to Move Up a Selected Row in Qt

Question

I have a QTableView with 3 rows and 2 columns. (Here I am using a QStandardItemModel). I want to move up/move down a single row when a QPushButton is clicked. How can I move up/down a row in QTableView?

Thanks for your reply vahancho. I have already tried using QAbstractItemModel::moveRow, but it doesn't work:

   int currentRow = ui->tableView->currentIndex().row();
   QModelIndex sourceParent = ui->tableView->model()->index(ui->tableView->selectionModel()->currentIndex().row(),0);
   QModelIndex destinationParent = ui->tableView->model()->index(ui->tableView->selectionModel()->currentIndex().row()+1,0);
   ui->tableView->model()->moveRow(sourceParent,currentRow, destinationParent,destinationParent.row());

It doesn't work because it is a virtual function you have to implement it yourself. — eric, Feb 22 '15 at 04:29
neuronet, thank you for your reply. So, are you saying that this function (`moveRow()`) does nothing if you do not implement it yourself? . So what is the idea of this function? — Angie Quijano, Sep 04 '15 at 17:14

score 6 · Answer 1 · edited Sep 04 '15 at 19:36

6

Use Qt documentation for QStandartItemModel - QStandardItemModel Class

takeRow
insertRow

edited Sep 04 '15 at 19:36

Angie Quijano

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answered Sep 09 '13 at 08:56

Dmitry Sazonov

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i agree, `QStandardItemModel` is more convinient :) – Zaiborg Sep 12 '13 at 07:58
I posted solution to author, but he deleted my post. Problem was that TS didn't know about type casting and he couldn't cast QModelIndex::model() to QStandartItemModel. – Dmitry Sazonov Sep 12 '13 at 08:04
@SaZ who is TS, what do you mean he deleted the post, he can't do that with such low rep can he? – eric Feb 22 '15 at 04:30
TS == topic starter. He posted an answer, and i commented it. So he deleted his answer and my comment became invisible. – Dmitry Sazonov Feb 22 '15 at 17:46

score 3 · Answer 2 · answered Sep 09 '13 at 08:20

3

If you use Qt5 you can take a look on this function:

bool QAbstractItemModel::moveRow(const QModelIndex & sourceParent, int sourceColumn, const QModelIndex & destinationParent, int destinationChild)

"On models that support this, moves sourceColumn from sourceParent to destinationChild under destinationParent. Returns true if the columns were successfully moved; otherwise returns false."

answered Sep 09 '13 at 08:20

vahancho

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abstractitemmodel, so it means you still need to implement it yourself, right? – eric Feb 18 '15 at 02:54
@neuronet, yes. Actually, to make `moveRow()` work, you need to implement `QAbstractItemModel::moveRows()` virtual function. – vahancho Feb 18 '15 at 07:34
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It is strange that this virtual function is available but no Qt classes implement it. – Rotsiser Mho Dec 11 '19 at 19:58

score 3 · Answer 3 · answered Dec 16 '13 at 17:14

Here is a short utility I use for moving the Qt::DisplayData of a row in QAbstractItemModel:

void CopyRowData( QAbstractItemModel * pModelDst, const QAbstractItemModel * pModelSrc, int nRowDst, int nRowSrc, const QModelIndex &parentDst /*= QModelIndex()*/, const QModelIndex &parentSrc /*= QModelIndex()*/, int nRole /*= Qt::DisplayRole*/ )
{
    if (parentSrc.isValid())
        assert(parentSrc.model() == pModelSrc);
    if (parentDst.isValid())
        assert(parentDst.model() == pModelDst);

    int nCols = pModelSrc->columnCount(parentSrc);

    for (int i = 0; i < nCols ; ++i)
        pModelDst->setData(pModelDst->index(nRowDst, i, parentDst), pModelSrc->index(nRowSrc, i, parentSrc).data(nRole), nRole);
}

bool MoveModelRows( QAbstractItemModel * pModel, int nSrcRow, int nDstRow, int nCount /*= 1*/, const QModelIndex &parent /*= QModelIndex()*/ )
{
    if (nSrcRow < 0 || nSrcRow >= pModel->rowCount(parent) ||
        nDstRow < 0 || nDstRow >= pModel->rowCount(parent))
        return false;

    if (nSrcRow == nDstRow)
        return true;

    int nDstRowNew = nSrcRow > nDstRow ? nDstRow : nDstRow + 1;

    if (!pModel->insertRows(nDstRowNew, nCount, parent))
        return false;

    int nSrcRowNew = nSrcRow > nDstRow ? nSrcRow + nCount : nSrcRow;

    for (int i = 0; i < nCount; ++i)
        CopyRowData(pModel, pModel, nDstRowNew + i, nSrcRowNew + i, parent, parent);

    pModel->removeRows(nSrcRowNew, nCount, parent);

    return true;
}

score 0 · Answer 4 · answered Sep 04 '15 at 19:55

Using the idea that SaZ said:

Use Qt documentation for QStandartItemModel - QStandardItemModel Class

takeRow

insertRow

This is the code I did for this purpose:

QModelIndexList selection = ui->tableView->selectionModel()->selectedRows();
int row = selection[0].row();
QList<QStandardItem*> itemList = ui->tableView->model()->takeRow(row);
ui->tableView->model()->insertRow(row-1,itemList);

I hope this help you.

score -1 · Answer 5 · answered May 24 '15 at 08:55

-1

I think this would help:

for(int colId=0;colId<ui->tableWidget->columnCount();++colId)
{
    QTableWidgetItem *item1=new QTableWidgetItem( *ui->tableWidget->item(id_row1,colId) );
    QTableWidgetItem *item2=new QTableWidgetItem( *ui->tableWidget->item(id_row2,colId) );

    ui->tableWidget->setItem(id_row1,colId, item2 );
    ui->tableWidget->setItem(id_row2,colId, item1 );
}

answered May 24 '15 at 08:55

OLS

1

This creates unnecessary copies using somewhat expensive heap allocations. – Rotsiser Mho Dec 11 '19 at 19:56

How to Move Up a Selected Row in Qt

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