Re: Digest for qdjango@googlegroups.com - 1 Message in 1 Topic

[William Tambellini]

Hi Pete,

 QSqlDatabase is usually not copy friendly.

 Strangely, the code from qdjango is not using a reference and consequently doing a copy :

QDjango::setDatabase(QSqlDatabase db)

vs

QDjango::setDatabase(QSqlDatabase &db)

 Perhpas Qt5 is more sensitive than Qt4 regarding that.

 If it could help.

Yours

William.

2013/6/25 <qdj...@googlegroups.com>

  Today's Topic Summary

Group: http://groups.google.com/group/qdjango/topics

• Is qdjango-db safe to use from Qt5 apps? [1 Update]

 Is qdjango-db safe to use from Qt5 apps?

Pete Woods <pete....@canonical.com> Jun 24 02:21AM -0700  

Hi,
 
I'm considering using qdjango in a Qt5 app I'm writing at the moment, but
I'm not getting very far with the examples.
 
For example:
QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
db.setDatabaseName(":memory:");
db.open();
QDjango::setDatabase(db);
 
Causes the following segmentation fault:
Program received signal SIGSEGV, Segmentation fault.
0x00007ffff49ea8d4 in QString::operator==(QLatin1String const&) const ()
from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
(gdb) bt
#0 0x00007ffff49ea8d4 in QString::operator==(QLatin1String const&) const
() from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#1 0x00007ffff70f2d08 in operator!= (s=..., this=0x7fffffffdc20) at
/usr/include/qt4/QtCore/qstring.h:413
#2 QDjango::setDatabase (database=...) at QDjango.cpp:164
 
If I copy the the same code from there into my code locally, e.g.:
 
QSqlDatabase database(db);
if (database.driverName() != QLatin1String("QSQLITE")
&& database.driverName() != QLatin1String("QSQLITE2")
&& database.driverName() != QLatin1String("QMYSQL")
&& database.driverName() != QLatin1String("QPSQL")) {
qWarning() << "Unsupported database driver" << database.driverName();
}
 
then that doesn't segfault. Is this problem the result of mixing qt4 and
qt5 libraries together?
 
I'm using the Ubuntu-packaged version of qdjango (0.2.6) on a 64-bit VM.
 
Cheers,
Pete


 

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