QTableView doesn't seem to react on dataChanged signal

Question

Shown below is the my custom table model. I am trying to use that tablemodel together with a QTableView. If the method append of the table model is called I would expect the table view to update its contents. But it doesn't and I don't know why. If however I use that same table model together with a QListView, everything works fine, i.e. the list view does update its contents, when append of the table model gets called. Is there anything special I need to do in case of the QTableView?

class MyModel : public QAbstractTableModel
{
public:

    MyModel(QObject* parent=NULL) : QAbstractTableModel(parent) {}

    int rowCount(const QModelIndex &parent = QModelIndex()) const {
        return mData.size();
    }

    int columnCount(const QModelIndex &parent = QModelIndex()) const {
        return 2;
    }

    QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const {
        if (!index.isValid()) {
            return QVariant();
        }

        if (role == Qt::DisplayRole) {
            if (index.column()==0) {
                return QVariant(QString::fromStdString(getFirst(index.row())));
            }
            if (index.column()==1) {
                return QVariant(QString::fromStdString(getSecond(index.row())));
            }
        }

        return QVariant();
    }

    void append(std::string const& first, std::string const& second) {
        mData.push_back(std::make_pair(first, second));

        emit dataChanged(index(mData.size()-1, 0), index(mData.size()-1, 1));
    }

    std::string const& getFirst(int i) const {
        return mData[i].first;
    }

    std::string const& getSecond(int i) const {
        return mData[i].second;
    }

protected:

    std::vector<std::pair<std::string, std::string> > mData;
};

call layoutChanged instead

iMath
– iMath

2024-02-18 12:08:00 +00:00
Commented Feb 18, 2024 at 12:08 — iMath
– iMath, Commented Feb 18, 2024 at 12:08

JediLlama · Accepted Answer · 2012-01-08 22:41:29Z

4

As you're inserting a new row instead of changing existing data, you should use beginInsertRows and endInsertRows instead:

void append(std::string const& first, std::string const& second) {
    int row = mData.size();
    beginInsertRows( QModelIndex(), row, row );

    mData.push_back(std::make_pair(first, second));

    endInsertRows();
}

See if that helps.

answered Jan 8, 2012 at 22:41

JediLlama

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2 Comments

qwerty9967 Over a year ago

This helped me. Do you have a link to the documentation where you found this answer?

JediLlama Over a year ago

Usage of beginInsertRows/endInsert rows can be found in the Qt documentation for the QAbstractItemModel class.

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