How to retrieve generated primary key when row was inserted with QSqlTableModel::insertRecord

Question

This question pertains to Qt 4.7.3 on Windows with Postgres.

I'm trying to insert a row into a pretty large table via QSqlTableModel, because this (hopefully) saves me the trouble of typing out the field names, by using QSqlTableModel::setTable. I ask the model for a record object with QSqlRecord row(QSqlTableModel::record);, and fill this with data via the QSqlRecord::setValue. Here's the code to persist the row:

const bool insertOk = tableModel.insertRecord(-1, row);

if (!insertOk || !tableModel.submitAll()) {
  return -1;
}

QSqlError err = tableModel.lastError();
if (err.type() != QSqlError::NoError) {
  std::cerr << "errormsg " << std::endl;
  return -1;
}

const int primaryKey = tableModel.query().lastInsertId().toInt();

The above is what I tried, but the content of tableModel.query() is a giant select, with no RETURNING keyword. lastInsertId() returns an invalid QVariant. Is it possible to have Qt provide the generated primary key without making an additional - fugly - roundtrip to the database. I'd rather not lock the table to ensure the last is actually the one I created, if I can avoid it.

Please advise.

Answer 1

"Solved" by using an additional query for LASTVAL(). Not sure if that's the correct way to use the Qt API. LASTVAL() is safe in transactions.