SQLite adding Table query fails

sandro4912

I have the following code:

    auto db = QSqlDatabase::addDatabase("QSQLITE", "Connection");
    db.setDatabaseName("test.db");
    if (!db.open()) {
        qDebug("Error occurred opening the database.");
        qDebug("%s.", qPrintable(db.lastError().text()));
        return;
    }

    if(!db.isDriverAvailable("QSQLITE"))
    {
        qDebug("Driver not available");
        return;
    }

    // Insert table.
    QSqlQuery query(db);
    qDebug() << query.prepare("CREATE TABLE IF NOT EXISTS test (id INTEGER PRIMARY KEY, text TEXT)");
    if (!query.exec()) {
        qDebug("Error occurred creating table.");
        qDebug() << db.lastError().text();
        return;
    }

When I try to insert a table the query fails and this part is excuted:

    if (!query.exec()) {
        qDebug("Error occurred creating table.");
        qDebug() << db.lastError().text();
        return;
    }

However theres no error code stating what went wrong. Console output is simply this:

true
Error occurred creating table.
" "

So what could be the reason for a query.excec() to fail?

As a side note I run Qt under KDE Neon Linux. Could it be a OS issue?

sandro4912

I found the answer myself. In linux you have to store the database under home according to http://qt.shoutwiki.com/wiki/Creating_an_SQLite_database_in_Qt

#ifdef Q_OS_LINUX
// NOTE: We have to store database file into user home folder in Linux
QString path(QDir::home().path());
path.append(QDir::separator()).append("test.sqlite");
path = QDir::toNativeSeparators(path);
db.setDatabaseName(path);
#else
// NOTE: File exists in the application private folder, in Symbian Qt implementation
db.setDatabaseName("test.sqlite");
#endif

That solved my issue now it works

I wonder whats the reason.

SGaist

Hi,

Your executable might be in a read-only folder and since you are using a relative path, it will try to create the file while it can not.

A better solution is to use QStandardPaths::writableLocation so you can get a suitable folder cross-platform.

sandro4912

Thanks for the hint. I changed it like this

QString path(QStandardPaths::writableLocation(
    QStandardPaths::StandardLocation::DesktopLocation));
path.append(QDir::separator()).append("test.sqlite");
path = QDir::toNativeSeparators(path);
db.setDatabaseName(path);

it seems to work