QSqlTableModel - unable to find table

MasterQ

Hi, once again.

The main issue I am struggling with at the moment is that my QSqlTableModel gives an error while select(). It states "unable to find table Dokumente".

But the table exists. See the following test:

auto context = new DocumentsDbContext();

qDebug() << "context->model()->select()" << context->model()->select();
qDebug() << "context->model()->lastError()" << context->model()->lastError();
qDebug();


auto sql = "SELECT name FROM sqlite_schema WHERE type ='table' AND name NOT LIKE 'sqlite_%';";
auto query = new QSqlQuery(sql, context->database());
qDebug() << "query->exec() #1" << query->exec();
while(query->next()) {
     qDebug() << "query->record().value(\"name\")" << query->record().value("name").toString();
}
delete query;

with following output:

context->model()->select() false
context->model()->lastError() QSqlError("", "Unable to find table Dokumente", "")

context->database().isValid() true
context->database().databaseName() "devel.db"
context->database().connectionName() "documents"
QFile::exists true
context->database().driverName() "QSQLITE"
query->exec() #1 true
...
query->record().value("name") "Dokumente"
...

What's going on here?

DocumentsDbContext wrappes the QSqlDatabase and the QSqlTableModel.

JonB

@MasterQ
It would be good to see the SQL statement reported as being executed for the context->model()->select() failure/Unable to find table Dokumente error?

MasterQ

@JonB

qDebug() << "context->model()->SelectStatement()" << context->model()->SelectStatement();

gives

context->model()->SelectStatement() ""

an empty string ??

Christian Ehrlicher

Please provide a minimal, compilable example and make sure the database is opened before a query is created.

MasterQ

@Christian-Ehrlicher

today I created a console testing application, copied all relevant stuff, and ...

what do you think?

Yes, it is working as intended, no issues, everything is fine. I then reimplemented all the testing code into my main project and ...

what do you think?

Yes, it is working also as intended, no issues, everything is fine.

It is gone over night! There are no changes, except that I added some test methods.

Yesterday I cleaned up the project and rebuilt it several times. No idea what happened.

BTW; everything is fine is not really correct. I now get an error message at

 auto db = QSqlDatabase::addDatabase(m_driver, m_connectionname);

qt.core.qobject.connect: QObject::connect(QObject, Unknown): invalid nullptr parameter

Also no changes in code from yesterday.

But is has no real effect. The code is running without issues.

Christian Ehrlicher

@MasterQ said in QSqlTableModel - unable to find table:

qt.core.qobject.connect: QObject::connect(QObject, Unknown): invalid nullptr parameter

Which exact Qt version do you use? Try to start it with QT_FATAL_WARNINGS to see where the message comes from.

MasterQ

@Christian-Ehrlicher

I am using 6.6.1.

setting environment variable QT_FATAL_WARNINGS=1 gives not much more information

qt.core.qobject.connect: QObject::connect(QObject, Unknown): invalid nullptr parameter
Signal: SIGABRT (Aborted)

The application stops at that point.

With QT_FATAL_WARNINGS= 0, no difference to without QT_FATAL_WARNINGS. The app is running until the end without any additional output.

Christian Ehrlicher

@MasterQ You should run it in a debugger to see where it asserts ...

MasterQ

@Christian-Ehrlicher said in QSqlTableModel - unable to find table:

@MasterQ You should run it in a debugger to see where it asserts ...

It is running in a debugger.

The current frames's file 'pthread_kill.c' is not found or its content differs from the compiled content. You may specify it manually.

The editor is pointing to some assembler code.

I am using CLion.

Christian Ehrlicher

Look at the backtrace... basic programming knowledge.

MasterQ

@Christian-Ehrlicher

you are right, that are basics. I just had it not on my focus. Please keep in mind that I am not a professional, just a hobbyist and a little bit out of shape about C++.

here is the backtrace:

__pthread_kill_implementation 0x00007ffff7099a1b
__pthread_kill_internal 0x00007ffff7099a1b
__GI___pthread_kill 0x00007ffff7099a1b
__GI_raise 0x00007ffff70428e6
__GI_abort 0x00007ffff70268b7
qAbort 0x00007ffff78b792c
qt_message_fatal<QString&> 0x00007ffff78edc05
qt_message(QtMsgType, const QMessageLogContext &, const char *, typedef __va_list_tag __va_list_tag *) 0x00007ffff78edc05
QMessageLogger::warning 0x00007ffff78b7f22
connectWarning 0x00007ffff78c17c5
QObjectPrivate::connectImpl 0x00007ffff79b015a
QObject::connectImpl 0x00007ffff79b0a2d

QObject::connect<…> qobject.h:235

QObject::connect<…> qobject.h:243
QtGlobalStatic::ApplicationHolder::pointer qapplicationstatic.h:53
QGlobalStatic::instance qglobalstatic.h:92
QGlobalStatic::operator() qglobalstatic.h:73
QSqlDatabasePrivate::driverDict 0x00007ffff7f85729
QSqlDatabasePrivate::init 0x00007ffff7f85729
QSqlDatabase::addDatabase 0x00007ffff7f85da2
libDatabase::DatabaseProvider::Database DatabaseProvider.cpp:41
Tests::databaseProvider Tests.cpp:39
main main.cpp:9
__libc_start_call_main 0x00007ffff7028150
__libc_start_main_impl 0x00007ffff7028209
_start 0x0000555555559d05

I am far away from knowing Qt source code. I have started again with Qt/C++ after around 25 years of a break just three or four weeks ago.

The issue seems not to come from my code, but from somewhere deep in Qt itself.

for whom it may be of interest:
small test program on github reproducing the issue

Christian Ehrlicher

Thx for the backtrace. QSqlDatabasePrivate::driverDict() is gone in 6.7 but I would guess you did not instantiate a Q(Core)Application before use create a QSqlDatabase.