An example 'Spin Box Delegate' code does not work using a tableView

[tonnot]

This is the original code :

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    QStandardItemModel model(4, 2);
    QTableView tableView;
    tableView.setModel(&model);
    tableView.horizontalHeader()->setStretchLastSection(true);
    for (int row = 0; row < 4; ++row) {
        for (int column = 0; column < 2; ++column) {
            QModelIndex index = model.index(row, column, QModelIndex());
            model.setData(index, QVariant((row+1) * (column+1)));
        }
    }
 
    tableView.setWindowTitle(QObject::tr("Spin Box Delegate"));
    tableView.show();
    return app.exec();
}

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    QStandardItemModel model(4, 2);
    QTableView tableView;
    tableView.setModel(&model);
    tableView.horizontalHeader()->setStretchLastSection(true);
    for (int row = 0; row < 4; ++row) {
        for (int column = 0; column < 2; ++column) {
            QModelIndex index = model.index(row, column, QModelIndex());
            model.setData(index, QVariant((row+1) * (column+1)));
        }
    }

    tableView.setWindowTitle(QObject::tr("Spin Box Delegate"));
    tableView.show();
    return app.exec();
}

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And this is my code (I use a TableView out on a window using Designer)

QStandardItemModel modelo(4, 2);
       ui->tableView->setModel(&modelo);
       ui->tableView->horizontalHeader()->setStretchLastSection(true);
       for (int row = 0; row < 4; ++row) {
           for (int column = 0; column < 2; ++column) {
               QModelIndex index = modelo.index(row, column, QModelIndex());
               modelo.setData(index, QVariant((row+1) * (column+1)));
           }
       }

QStandardItemModel modelo(4, 2);
       ui->tableView->setModel(&modelo);
       ui->tableView->horizontalHeader()->setStretchLastSection(true);
       for (int row = 0; row < 4; ++row) {
           for (int column = 0; column < 2; ++column) {
               QModelIndex index = modelo.index(row, column, QModelIndex());
               modelo.setData(index, QVariant((row+1) * (column+1)));
           }
       }

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(I only delete the 'delegate' code, in order to simply test how it works)
Ok, in my case I see the table but i dont see the cells neither its content.
What happens ?

[tbscope]

You defined your model on the stack and it gets deleted at the end of the function (which I guess is your constructor)

[tonnot]

Thank you for your answer.
But... I dont understand your explanation...
The only difference between the original code and mine is that I use a tableView accesdesd 'via' the ui->.
And, how can I avoid the destruction ?
Thanks for your patience.

[Lykurg]

The only difference between the original code and mine is that I use a tableView accesdesd 'via' the ui->.

And that is exactly the difference why their code is working and yours not! And it is basic C++, so take any c++ book and read about dynamic and static allocation and how long objects lives.

[ChrisW67]

Thank you for your answer.
But... I dont understand your explanation...

Items allocated on the stack, like modelo, only exist to the end of the enclosing block (usually a method/function). You need to look at the differences between where you have modelo declared and where the original example has its model. What is the lifetime of the two objects?