Data type comparison problem



  • Hi,
    I'm trying to align data in QTableView columns based on their data type. Data are retrieved from MySQL database through QSqlTableModel. I tried to compare the type of data at the data function subclassed from QSqlTableModel, with the following code:
    @
    QVariant TableModel::data(const QModelIndex &index, int role) const
    {
    QVariant dtype = QSqlTableModel::data(index, role).type();
    qDebug() << "Data Type:" << dtype;

    if (role == Qt::TextAlignmentRole)
    {
        if (dtype == QVariant::String) return Qt::AlignLeft + Qt::AlignVCenter;
        else return Qt::AlignRight + Qt::AlignVCenter;
    }
    return QSqlTableModel::data(index, role);
    

    }
    @

    The comparison doesn't seem to work as expected, making all columns appear as right aligned.
    Where did I go wrong? Can anyone help, please?


  • Moderators

    welcome to devnet

    You check dtype, but not role. So, there could be the problem. Otherwise you probably have to use the debugger and look in more detail what is there.



  • maybe

    @QVariant dtype = QSqlTableModel::data(index, role).type();@

    should be

    @QVariant::Type dtype = QSqlTableModel::data(index, role).type();@

    QVariant::type() returns enum not another QVairant.

    PS: QVariant::QVariant ( Type type ) Constructs a null variant of type type. From docs.



  • The QVariant::Type might be any kind of variable able to hold the enumarator value. An int might be enough ;-)
    Maybe remove the local variable at all? KISS is always a good advice. so maybe more like:
    @
    data()
    {
    qDebug() << QSqlTableModel::data(index.role).type();
    if (role == Qt::TextAlignmentRole)
    {
    if (QSqlTableModel::data(index, role).type() == Qt::TextAlignmentRole)
    {
    // do your return stuff
    }
    }
    }
    @



  • Thank you all for the replies. Changed the code with:
    @
    QVariant::Type dtype = QSqlTableModel::data(index, role).type();
    @
    as it should, then added more qDebug between the lines, and found out that Qt spits out empty data while role == Qt::TextAlignmentRole. So I went back to the Docs and decided to reimplement views rendering using delegates. More in line to MVC pattern, I think.


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