I don't know about mapper, but here is how I initialize my combo boxes with db values:

Qt Code:
  1. // Retrieves the preferences to populate the dialog when it opens
  2. void PreferencesDialog::getPreferences(QString ctrlConn)
  3. {
  4. QSqlDatabase db = QSqlDatabase::database(ctrlConn);
  5. db.open();
  6. QSqlRecord record;
  7. QSqlTableModel* model = new QSqlTableModel(this, db);
  8. model->setTable("preferences");
  9. model->select();
  10. record = model->record(0);
  11.  
  12. m_ui->cbPort->setCurrentIndex(m_ui->cbPort->findText(record.value("port").toString()));
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Does that help any?