PySide + QtSql - cannot load database drivers

Question

Edit: I had to change the question because I found that the problem related not only to ODBC driver bu to all drivers such as MYSQL, SQLITE etc.

So the problem is this: I try to connect to a database using PySide and QtSql module.

The critical snippet:

from PySide import QtGui
from PySide import QtSql
import sys

if __name__ == "__main__":
    app = QtGui.QApplication(sys.argv)
    db = QtSql.QSqlDatabase.addDatabase('QODBC')  
    # or others: QMYSQL, QSQLITE etc.
    sys.exit(app.exec_())

and when I try to run it, I get a message:

QSqlDatabase: QODBC driver not loaded
QSqlDatabase: available drivers:

When I try equivalent PyQt4 instead of PySide, I get no message which I assume means that the ODBC driver is available with PyQt4. However, unfortunately, I cannot switch my application from PySide to PyQt4 for many other reasons.

When I look into Python Lib folder I can see that python-3.3.2\Lib\site-packages\PySide\plugins\sqldrivers contains DLLs including qsqlodbc4.dll. So there is something more missing and I do not know what.

As I wrote the problem is not just with ODBC but with all database drivers.

what is the version of PySide ? For PySide older than 1.2.0 you need to call the PySide post-install script after installing, to generate the qt.conf file. For example: c:\Python33\Scripts\python.exe c:\Python33\Scripts\pyside_postinstall.py -install — rlacko, Apr 26 '14 at 19:47
It is version 1.2.1. It was bundled and installed with WinPython 3.3.2.3. When I look at intsllation log, it tells me that the post-install script was run. Even after I run it manullay myself, the problem with ODBC still exists. — HiFile.app - best file manager, Apr 27 '14 at 07:08

score 1 · Accepted Answer · edited May 23 '17 at 11:49

1

Found a solution here on stackoverflow here (relates to PyQt rather than PySide but it works): PyQT can't find any SQL drivers

In short - put this code before calling addDatabase:

site_pack_path = site.getsitepackages()[1]
QtGui.QApplication.addLibraryPath('{0}\\PySide\\plugins'.format(site_pack_path))

edited May 23 '17 at 11:49

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answered Apr 27 '14 at 08:29

HiFile.app - best file manager

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this is what the post-install script should do. Maybe there is some bug in post-install script. Could you run the script and send me here the output ? thanks – rlacko Apr 27 '14 at 19:26
@V.K Any word on why this fix is even needed? It seems like a bug. Has it been reported to PySide, do you know? – eric Oct 30 '14 at 13:21

Nishi · Answer 2 · 2022-05-14T12:06:46.463

If you encounter a similar issue using modern PySide6, here is the full answer: https://stackoverflow.com/a/72169911/211369

One of solutions is to define the QT_PLUGIN_PATH environment variable, so that it contains the "sqldrivers" sub-directory with SQL plugins for Qt platform.

In your example, QT_PLUGIN_PATH=c:/python-3.3.2/Lib/site-packages/PySide/plugins

BTW almost a half of info known to me is is officially published at https://doc.qt.io/qt-6/deployment-plugins.html

PySide + QtSql - cannot load database drivers

2 Answers2