Qt - sync SQLite data base on application close

Question

Data base is oppened in application by following code:

db = QSqlDatabase::addDatabase("QSQLITE");
bool dbExists = QFile::exists("base.db");
db.setDatabaseName("base.db"); // ":memory:"
if (!db.open()) {
    db.close();
    QMessageBox::critical(0, tr("Cannot open database"),
                          tr("Unable to establish a database connection.\n"
                             "This example needs SQLite support. Please read "
                             "the Qt SQL driver documentation for information how "
                             "to build it."), QMessageBox::Cancel);
    return;
}
if (!dbExists)
    createDB();

I've mapped some tables to widgets via QDataWidgetMapper. All work fine during application run. Changes take effect. But all the chages are lost after restarting application with existing base.db. Application starts much faster, so it opens this file but with unchanged data base.

I've tried to close application by

db.close();
this->close();

There is no luck. Even the sync query did not help after db.open:

QSqlQuery query(db);
query.exec("PRAGMA synchronous = ON;");

What have I missed to sync changes to base.db?

UPDATE. You can try to build sqlwidgetmapper standard example and change :memory: to "base.db" file. It doesn't save changed data to file too.

Please add the code showing how you set up the QWidgetDataMapper and the model it uses. I made a wild guess at the problem, but even if I guessed right and that solves the problem, please add the code for the benefit if others. — hyde
– hyde, Commented Sep 21, 2016 at 19:38

hyde · Accepted Answer · 2016-09-21 19:35:28Z

2

Problem is possibly manual submit policy.

Either switch that to auto, or manually call QDataWidgetMapper::submit() at appropriate time (before new value is lost from the widget).

answered Sep 21, 2016 at 19:35

hyde

63.2k22 gold badges128 silver badges182 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Stanislav Fyodorov Over a year ago

Thank you, hyde. OnFieldChange works just fune. There is no OnAutoSubmit in QSqlTableModel.

Collectives™ on Stack Overflow

Qt - sync SQLite data base on application close

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related