#include <QtGui>
#include <QSqlTableModel>
#include <QItemDelegate>
#include <QMainWindow>
#include <QVBoxLayout>
#include <QDataWidgetMapper>
#include <QLineEdit>
#include <QSqlQuery>
#include <QApplication>
#include <QPushButton>

class MainWindow : public QMainWindow
{
    Q_OBJECT
public:
    MainWindow(QWidget *parent = 0)
        : QMainWindow(parent)
    {
        QWidget *w = new QWidget(this);
        setCentralWidget(w);
        QVBoxLayout *l = new QVBoxLayout(w);
        QLineEdit *edit1 = new QLineEdit(w);
        QLineEdit *edit2 = new QLineEdit(w);
        QPushButton *button1 = new QPushButton("Submit", w);
        QPushButton *button2 = new QPushButton("Go to first", w);
        QPushButton *button3 = new QPushButton("Go to last", w);
        l->addWidget(edit1);
        l->addWidget(edit2);
        l->addWidget(button1);
        l->addWidget(button2);
        l->addWidget(button3);

        QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
        db.setDatabaseName("sample.sqlite");
        if (!db.open()) {
            Q_ASSERT(0);
        }
        QSqlQuery q(db);
        if (q.exec("CREATE TABLE fields (field1 VARCHAR(128), field2 VARCHAR(128));")) {
            q.exec("INSERT INTO fields (field1, field2) VALUES ('aaaaa', 'bbbbb')");
            q.exec("INSERT INTO fields (field1, field2) VALUES ('ccccc', 'ddddd')");
        }

        model = new QSqlTableModel(this);
        model->setTable("fields");
        model->select();
        model->setEditStrategy(QSqlTableModel::OnFieldChange);

        mapper = new QDataWidgetMapper(this);
        mapper->setModel(model);
        mapper->setSubmitPolicy(QDataWidgetMapper::ManualSubmit);
        mapper->setItemDelegate(new QItemDelegate(this));

        mapper->addMapping(edit1, model->fieldIndex("field1"));
        mapper->addMapping(edit2, model->fieldIndex("field2"));
        mapper->toFirst();

        connect(button1, &QPushButton::clicked,
                this, &MainWindow::onButtonClicked);
        connect(button2, &QPushButton::clicked,
                mapper, &QDataWidgetMapper::toFirst);
        connect(button3, &QPushButton::clicked,
                mapper, &QDataWidgetMapper::toLast);
    }
private slots:
    void onButtonClicked() {
        disconnect(model, &QSqlTableModel::dataChanged,
                   mapper, 0);
        mapper->submit();
    }
private:
    QSqlTableModel *model;
    QDataWidgetMapper *mapper;
};

#include "modified_main.moc"

int main(int argc, char **argv)
{
    QApplication app(argc, argv);
    MainWindow mw;
    mw.show();
    return app.exec();
}