Qt5.11.2, QSqlDatabase, QMYSQL, Driver not loaded

SGaist

Before trying to build anything (you need to first download the sources for that). Please run your application with the QT_DEBUG_PLUGINS environment variable set to 1.

Click on the Project button on the vertical toolbar on the left of Qt Creator, and there you'll find the Build and Run settings. Modify the Environment in the Run settings.

SPlatten

@SGaist , I did that, hasn't helped.

SGaist

It's not supposed to change anything in the application execution. The goal is to provide you with additional information about what is happening when plugins are getting or not loaded and from there help find what might be going wrong.

SPlatten

@SGaist said in Qt5.11.2, QSqlDatabase, QMYSQL, Driver not loaded:

QT_DEBUG_PLUGINS

With QT_DEBUG_PLUGINS added to the environment the output when single stepping over:

    QSqlDatabase db = QSqlDatabase::addDatabase("QMYSQL");

Is:

2018-10-11 08:28:13.253913+0100 SimonQtWidgets[1031:41669] Got keys from plugin meta data ("QPSQL7", "QPSQL")
2018-10-11 08:28:13.253927+0100 SimonQtWidgets[1031:41669] QFactoryLoader::QFactoryLoader() checking directory path "/Users/simonplatten/build-SimonQtWidgets-Desktop_Qt_5_11_2_clang_64bit-Debug/SimonQtWidgets.app/Contents/MacOS/sqldrivers" ...
2018-10-11 08:28:13.255823+0100 SimonQtWidgets[1031:41669] Cannot load library /Users/simonplatten/Qt/5.11.2/clang_64/plugins/sqldrivers/libqsqlmysql.dylib: (dlopen(/Users/simonplatten/Qt/5.11.2/clang_64/plugins/sqldrivers/libqsqlmysql.dylib, 133): Library not loaded: /usr/local/mysql/lib/libmysqlclient.20.dylib
  Referenced from: /Users/simonplatten/Qt/5.11.2/clang_64/plugins/sqldrivers/libqsqlmysql.dylib
  Reason: image not found)
2018-10-11 08:28:13.255844+0100 SimonQtWidgets[1031:41669] QLibraryPrivate::loadPlugin failed on "/Users/simonplatten/Qt/5.11.2/clang_64/plugins/sqldrivers/libqsqlmysql.dylib" : "Cannot load library /Users/simonplatten/Qt/5.11.2/clang_64/plugins/sqldrivers/libqsqlmysql.dylib: (dlopen(/Users/simonplatten/Qt/5.11.2/clang_64/plugins/sqldrivers/libqsqlmysql.dylib, 133): Library not loaded: /usr/local/mysql/lib/libmysqlclient.20.dylib\n  Referenced from: /Users/simonplatten/Qt/5.11.2/clang_64/plugins/sqldrivers/libqsqlmysql.dylib\n  Reason: image not found)"
2018-10-11 08:28:13.255
859+0100 SimonQtWidgets[1031:41669] QSqlDatabase: QMYSQL driver not loaded
2018-10-11 08:28:13.255885+0100 SimonQtWidgets[1031:41669] QSqlDatabase: available drivers: QSQLITE QMYSQL QMYSQL3 QPSQL QPSQL7

jsulm

@SPlatten said in Qt5.11.2, QSqlDatabase, QMYSQL, Driver not loaded:

Library not loaded: /usr/local/mysql/lib/libmysqlclient.20.dylib

Do you have this lib in that location?

SPlatten

@jsulm , No, I've no idea what this library is or where is comes from. The path /usr/local/mysql doesn't exist.

jsulm

@SPlatten This is the MySQL client library which is used by Qt to access MySQL databases. You need it if you want to use MySQL.

SPlatten

@jsulm said in Qt5.11.2, QSqlDatabase, QMYSQL, Driver not loaded:

libmysqlclient.20.dylib

I've found what I think is the correct library on my system:

    /usr/local/Cellar/mariadb/10.2.6/lib/libmariadb.dylib

I then tried:

    sudo ln -s /usr/local/Cellar/mariadb/10.2.6/lib/libmariadb.dylib /usr/local/lib/libmysqlclient.20.dylib

Re-ran in debug and the problem has changed, looks like I'm using the wrong library now:

2018-10-11 09:15:08.331712+0100 SimonQtWidgets[1644:135071] Got keys from plugin meta data ("QPSQL7", "QPSQL")
2018-10-11 09:15:08.331726+0100 SimonQtWidgets[1644:135071] QFactoryLoader::QFactoryLoader() checking directory path "/Users/simonplatten/build-SimonQtWidgets-Desktop_Qt_5_11_2_clang_64bit-Debug/SimonQtWidgets.app/Contents/MacOS/sqldrivers" ...
2018-10-11 09:15:08.347152+0100 SimonQtWidgets[1644:135071] Cannot load library /Users/simonplatten/Qt/5.11.2/clang_64/plugins/sqldrivers/libqsqlmysql.dylib: (dlopen(/Users/simonplatten/Qt/5.11.2/clang_64/plugins/sqldrivers/libqsqlmysql.dylib, 133): Library not loaded: /usr/local/mysql/lib/libmysqlclient.20.dylib
  Referenced from: /Users/simonplatten/Qt/5.11.2/clang_64/plugins/sqldrivers/libqsqlmysql.dylib
  Reason: Incompatible library version: libqsqlmysql.dylib requires version 20.0.0 or later, but libmysqlclient.20.dylib provides version 3.0.0)
2018-10-11 09:15:08.347182+0100 SimonQtWidgets[1644:135071] QLibraryPrivate::loadPlugin failed on "/Users/simonplatten/Qt/5.11.2/clang_64/plugins/sqldrivers/libqsqlmysql.dylib" : "Cannot load library /Users/simonplatten/Qt/5.11.2/clang_64/plugins/sqldrivers/libqsqlmysql.dylib: (dlopen(/Users/simonplatten/Qt/5.11.2/clang_64/plugins/sqldrivers/libqsqlmysql.dylib, 133): Library not loaded: /usr/local/mysql/lib/libmysqlclient.20.dylib\n  Referenced from: /Users/sim
onplatten/Qt/5.11.2/clang_64/plugins/sqldrivers/libqsqlmysql.dylib\n  Reason: Incompatible library version: libqsqlmysql.dylib requires version 20.0.0 or later, but libmysqlclient.20.dylib provides version 3.0.0)"
2018-10-11 09:15:08.347201+0100 SimonQtWidgets[1644:135071] QSqlDatabase: QMYSQL driver not loaded
2018-10-11 09:15:08.347228+0100 SimonQtWidgets[1644:135071] QSqlDatabase: available drivers: QSQLITE QMYSQL QMYSQL3 QPSQL QPSQL7

SGaist

Don't use ln that won't help, use install_name_tool and update the path in libqsqlmysql.dylib to match what you have on your system.

SPlatten

@SGaist, thank you, do you have an example? How do I achieve this?

SGaist

Did you read the tool's help ?

install_name_tool -change /usr/local/mysql/lib/libmysqlclient.20.dylib /path/to/mariadb/libmariadbclient.X.dylib /Users/hasan/Qt5.9.1/5.9.1/clang_64/plugins/sqldrivers/libqsqlmysql.dylib

Note that MariaDB should be a drop-in replacement however I haven't tried to "re-link" to a library that has different name (just a different compatible version number) so you may have other surprises.

SPlatten

@SPlatten said in Qt5.11.2, QSqlDatabase, QMYSQL, Driver not loaded:

2018-10-11 09:15:08.331712+0100 SimonQtWidgets[1644:135071] Got keys from plugin meta data ("QPSQL7", "QPSQL")
2018-10-11 09:15:08.331726+0100 SimonQtWidgets[1644:135071] QFactoryLoader::QFact

@SGaist

I'm struggling, the only libmariadbclient I can find on my entire system is:

    /usr/local/Cellar/mariadb/10.2.6/lib/libmariadbclient.a

SGaist

Then that's something you have to check with the brew folks.

SPlatten

@SGaist , I was looking for an .so library, I've now learnt that a .dylib is the mac os equivalent.

The database I'm using is MariaDB, I've just updated this using:

 brew upgrade mariadb

Then:

brew services restart mariadb

This has added:

/usr/local/Cellar/mariadb/10.3.10/lib

Containing:

-rwxr-xr-x  1 simonplatten  staff  1425020 13 Sep 05:40 libqsqlite.dylib
drwxr-xr-x  3 simonplatten  staff       96  4 Oct 13:26 libqsqlite.dylib.dSYM
-rwxr-xr-x  1 simonplatten  staff  1435972 13 Sep 05:38 libqsqlite_debug.dylib
drwxr-xr-x  3 simonplatten  staff       96  4 Oct 13:26 libqsqlite_debug.dylib.dSYM
-rwxr-xr-x  1 simonplatten  staff    79864 13 Sep 05:40 libqsqlmysql.dylib
drwxr-xr-x  3 simonplatten  staff       96  4 Oct 13:26 libqsqlmysql.dylib.dSYM
-rwxr-xr-x  1 simonplatten  staff   137448 13 Sep 05:38 libqsqlmysql_debug.dylib
drwxr-xr-x  3 simonplatten  staff       96  4 Oct 13:26 libqsqlmysql_debug.dylib.dSYM
-rwxr-xr-x  1 simonplatten  staff    88980 13 Sep 05:40 libqsqlpsql.dylib
drwxr-xr-x  3 simonplatten  staff       96  4 Oct 13:26 libqsqlpsql.dylib.dSYM
-rwxr-xr-x  1 simonplatten  staff   138612 13 Sep 05:38 libqsqlpsql_debug.dylib
drwxr-xr-x  3 simonplatten  staff       96  4 Oct 13:26 libqsqlpsql_debug.dylib.dSYM

Looking at the debug output from the Application Output:

2018-10-12 02:33:13.197110+0100 SimonQtWidgets[6965:134266] Cannot load library /Users/simonplatten/Qt/5.11.2/clang_64/plugins/sqldrivers/libqsqlmysql.dylib: (dlopen(/Users/simonplatten/Qt/5.11.2/clang_64/plugins/sqldrivers/libqsqlmysql.dylib, 133): Library not loaded: /usr/local/mysql/lib/libmysqlclient.20.dylib
  Referenced from: /Users/simonplatten/Qt/5.11.2/clang_64/plugins/sqldrivers/libqsqlmysql.dylib
  Reason: image not found)

Why is it trying to load libmysqlclient.20.dylib ?

The next line in the Application output:

2018-10-12 02:33:13.197133+0100 SimonQtWidgets[6965:134266] QLibraryPrivate::loadPlugin failed on "/Users/simonplatten/Qt/5.11.2/clang_64/plugins/sqldrivers/libqsqlmysql.dylib" : "Cannot load library /Users/simonplatten/Qt/5.11.2/clang_64/plugins/sqldrivers/libqsqlmysql.dylib: (dlopen(/Users/simonplatten/Qt/

Then:

(dlopen(/Users/simonplatten/Qt/5.11.2/clang_64/plugins/sqldrivers/libqsqlmysql.dylib, 133): Library not loaded: /usr/local/mysql/lib/libmysqlclient.20.dylib\n  Referenced from: /Users/simonplatten/Qt/5.11.2/clang_64/plugins/sqldrivers/libqsqlmysql.dylib\n  Reason: image not found)"
2018-10-12 02:33:13.1
97150+0100 SimonQtWidgets[6965:134266] QSqlDatabase: QMYSQL driver not loaded

SPlatten

@SPlatten said in Qt5.11.2, QSqlDatabase, QMYSQL, Driver not loaded:

libmysqlclient.20.dylib

@SGaist , I managed to progress the issue, this is what I did:

Manually create the required folder structure, from /usr/local:

sudo mkdir mysql
cd mysql
sudo mkdir lib
cd lib

Then create a symbolic link to the required library:

sudo ln -s /usr/local/lib/libmysqlclient.dylib /usr/local/mysql/lib/libmysqlclient.20.dylib

Now debugging the same project, the call to open still fails with:

2018-10-12 08:44:19.696706+0100 SimonQtWidgets[1253:117317] loaded library "/Users/simonplatten/Qt/5.11.2/clang_64/plugins/sqldrivers/libqsqlmysql.dylib"
2018-10-12 08:44:39.663805+0100 SimonQtWidgets[1253:117317] QSqlError("1130", "QMYSQL: Unable to connect", "Host '192.168.1.158' is not allowed to connect to this MariaDB server")
2018-10-12 08:44:40.409469+0100 SimonQtWidgets[1253:117317] Failed to connect.

Now resolved, the issue here was that the call to setHostName was using the host name of the system, I changed this to localhost and now everything works.

SGaist

That shouldn't be necessary but at least it got you going further.

As for your second error, this is your database configuration you have to inspect.

Is it a remote machine ? If not then replace the host name with localhost and try again.