How to display periodically updated data in QTableView

[MarekR22]

If you are lazy and dont care about perfomance you can use QAbstractItemModel::beginResetModel and QAbstractItemModel::endResetModel.
If you are just changing some values then emit signal: QAbstractItemModel::dataChanged.

[nickla]

I am lazy, because it cost 10 ms for 100 rows to delete and insert. I found the answer in a brainstorming session last night.

My mistake was simple. I have not cleaned the data before I save new.

This is my code for others:

void TxTableModel::parseXml(const QByteArray &xml)
{
    QXmlInputSource inputSource;
    QXmlSimpleReader reader;
    TxSaxTableHandler handler(&m_Data, false);
 
    inputSource.setData(xml);
    reader.setContentHandler(&handler);
    reader.setErrorHandler(&handler);
 
    QModelIndexList selectedList = parent->selectionModel()->selectedRows();
 
    beginResetModel();
    m_Data.clearData();
    reader.parse(inputSource);
    endResetModel();
 
    for( int i=0; i<selectedList.count(); i++) {
        parent->selectRow(selectedList.at(i).row());
    }
}

void TxTableModel::parseXml(const QByteArray &xml)
{
    QXmlInputSource inputSource;
    QXmlSimpleReader reader;
    TxSaxTableHandler handler(&m_Data, false);

    inputSource.setData(xml);
    reader.setContentHandler(&handler);
    reader.setErrorHandler(&handler);

    QModelIndexList selectedList = parent->selectionModel()->selectedRows();

    beginResetModel();
    m_Data.clearData();
    reader.parse(inputSource);
    endResetModel();

    for( int i=0; i<selectedList.count(); i++) {
        parent->selectRow(selectedList.at(i).row());
    }
}

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[wysota]

Just be aware that if you reset the model, you'll lose the selection and positioning in all the views attached to the model.

[nickla]

I can already see it. Is there any way to restore the scroll?

[wysota]

Don't reset the model

[nickla]

I cant. Line change so often that it is much easier to reset the entire model than to merge

[wysota]

I cant. Line change so often that it is much easier to reset the entire model than to merge

Then you won't retain scrolling and selection. Simple as that. It's either easy or effective, the choice is yours.

[ferrabras]

I had a similar problem and even tried to retain unique data from each selected itens before modelReset and then, after modelReset I tried to search for the data in then new model and finaly select the respective position at the view. Did not work or I was doing something really wrong. I finally surrendered to the model merging process. It is working like a charm but model merging took me a while to figure out!

[nickla]

This is my NonMerge method:

void TxTableModel::parseXml(const QByteArray &xml)
{
    QXmlInputSource inputSource;
    QXmlSimpleReader reader;
    TxSaxTableHandler handler(&m_Data, false);
 
    inputSource.setData(xml);
    reader.setContentHandler(&handler);
    reader.setErrorHandler(&handler);
 
    QModelIndexList selectedList = parent->selectionModel()->selectedRows();
    QModelIndex scrollTopIndex = parent->indexAt(QPoint(1, 1));
    QModelIndex scrollBottomIndex = parent->indexAt(QPoint(1, parent->height() - 1));
 
    beginResetModel();
    m_Data.clearData();
    reader.parse(inputSource);
    endResetModel();
 
    if (scrollBottomIndex.row() == -1) {
        parent->scrollToBottom();
    } else {
        parent->scrollTo(scrollTopIndex);
    }
 
    if (selectedList.count() > 0 && (selectedList.at(0).row() >= scrollTopIndex.row()) && (scrollBottomIndex.row() == -1 || scrollBottomIndex.row() > selectedList.at(0).row() )) {
        parent->selectRow(selectedList.at(0).row());
    }
}

void TxTableModel::parseXml(const QByteArray &xml)
{
    QXmlInputSource inputSource;
    QXmlSimpleReader reader;
    TxSaxTableHandler handler(&m_Data, false);

    inputSource.setData(xml);
    reader.setContentHandler(&handler);
    reader.setErrorHandler(&handler);

    QModelIndexList selectedList = parent->selectionModel()->selectedRows();
    QModelIndex scrollTopIndex = parent->indexAt(QPoint(1, 1));
    QModelIndex scrollBottomIndex = parent->indexAt(QPoint(1, parent->height() - 1));

    beginResetModel();
    m_Data.clearData();
    reader.parse(inputSource);
    endResetModel();

    if (scrollBottomIndex.row() == -1) {
        parent->scrollToBottom();
    } else {
        parent->scrollTo(scrollTopIndex);
    }

    if (selectedList.count() > 0 && (selectedList.at(0).row() >= scrollTopIndex.row()) && (scrollBottomIndex.row() == -1 || scrollBottomIndex.row() > selectedList.at(0).row() )) {
        parent->selectRow(selectedList.at(0).row());
    }
}

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But I really hope that you would not use this. It makes me a lot of pain to support (edit cell is something terrible) and I`m working on merge too.