Catching SQL errors using Qt - c++

Question

The code below doesn't work for catching sql errors with Qt and sqlite. I've also tried isNull. I'm getting a blank string for lasterror.text() and -1 for error number with working queries. I don't understand why isEmpty or isNull aren't working.
if (!query.lastError().text().isEmpty())
{
logfile(sqlstatement);
logfile("SqLite error:" + query.lastError().text());
logfile("SqLite error code:"+ QString::number( query.lastError().number() ));
}

Answer 1

Do you really execute your query?
Take a look at way of doing access do SQLite DB + logging in OpenSource application Mixxx (Opening database, applying query):
...
#define LOG_FAILED_QUERY(query) qDebug() << __FILE__ << __LINE__ << "FAILED QUERY [" \
<< (query).executedQuery() << "]" << (query).lastError()
...
// Check if you have QSQLITE2/QSQLITE driver avaiable
qDebug() << "Available QtSQL drivers:" << QSqlDatabase::drivers();
m_db.setHostName(...);
m_db.setDatabaseName(...);
m_db.setUserName(...);
m_db.setPassword(...);
bool ok = m_db.open();
qDebug() << "DB status:" << m_db.databaseName() << "=" << ok;
if (m_db.lastError().isValid()) {
qDebug() << "Error loading database:" << m_db.lastError();
}
...
QSqlQuery query(m_database);
query.setForwardOnly(true);
query.prepare(queryString);
if (!query.exec()) {
LOG_FAILED_QUERY(query);
return;
}
And be sure that this works :)