MySQL driver detected but not loading on MacOS

juneleung

I had a similar problem,
When I packaged the postgresql program, it was fine to run it locally, but when I opened the program on another computer, it prompted
"QSqlDatabase: QPSQL driver not loaded.
QSqlDatabase: available drivers: QSQLITE QODBC QODBC3 QPSQL QPSQL7",
it seems that the driver of postgresql is not loaded.
Why this the problem happened? Is there something wrong with the package? How should I set it?
Could anyone guide me how to solve it?

SGaist

@juneleung hi and welcome to devnet,

You have to deploy the PostgreSQL library along your application. Did you use macdeployqt to deploy your application ?

juneleung

Hi @SGaist
Yes, i have use macdeployqt to make it to a dmg file.
but when open it in another MacBook, it cant link with sql and notice driven not loaded driven not loaded.

artwaw

@juneleung AFAIR you need to manually deploy libpq.5.xx.dylib and relink your binary inside the .app to link to that - macdeployqt will not do it for you. I remember scripting that when I wrote a tool to interface with PostgreSQL. You'd need install-name-tool to do that.

SGaist

@artwaw not the binary, the plugin.

artwaw

@SGaist You are right, of course, it's been a while since I dipped my fingers into this abyss.

At any rate, I dug out my script, it will require some polishing but the gist is:

#!/bin/zsh
cp -fR ~/cpp/build-appName-Desktop_Qt_5_15_2_clang_64bit-Release/appName.app .
macdeployqt appName.app -verbose=1 -always-overwrite
cp -f *.dylib appName.app/Contents/Frameworks/
install_name_tool -change /Applications/Postgres.app/Contents/Versions/9.6/lib/libpq.5.dylib @executable_path/../Frameworks/libpq.5.dylib appName/Contents/PlugIns/sqldrivers/libqsqlpsql.dylib
install_name_tool -change libpq.5.dylib @executable_path/../Frameworks/libpq.5.dylib appName.app/Contents/MacOS/appName

That works under assumption that you have all necessary Postgres files and your .app package in the same folder as the script. Or - at least - was working for the Qt 5.15.2.

I replaced my app name with appName.

juneleung

@artwaw Hi,
I dont have any Postgres files' *.dylib in my app dir and my app/Contents/Plugins/sqldrivers/ folder dont have libqsqlpsql.dylib, only libqsqlite.dylib libqsqlodbc.dylib and libqsqlpsql.dylib.
Where to make it create this dylib or where to copy it ? Which dylibs are postgresql needed?
Thanks!

SGaist

libpq.5.dylib is provided through the PostgresApp.

artwaw

@juneleung Like @SGaist said. It is old and well know problem (I really thought addressed by now) that the plugin links to Postgres installation, somewhere in /Application/Postgres.app/[...]/libpq.5.dylib and in order to deploy the program properly one has to dabble and relink. I got annoyed and bored and semiautomated the deployment as above (I also wrote myself some script tools for signing and notarisation, because lack of integration is prevalent on macOS).

Nonetheless - once you get hang on the particular quirks like this one, deploying on macOS is a relative breeze.

juneleung

@artwaw @SGaist

Hi, I use these cmd :

cp /Applications/Postgres.app/Contents/Versions/14/lib/libpq.5.14.dylib /Users/test/Build/build-test-Desktop_Qt_5_15_2_clang_64bit-Release/test.app/Contents/Frameworks/

install_name_tool -change /Applications/Postgres.app/Contents/Versions/14/lib/libpq.5.dylib @executable_path/../Frameworks/libpq.5.14.dylib test/Contents/PlugIns/sqldrivers**/libqsqlpsql.dylib**

install_name_tool -change libpq.5.dylib @executable_path/../Frameworks/libpq.5.14.dylib test.app/Contents/MacOS/test

but an error with I don't have the libqsqlpsql.dylib in sqldrivers folder, and i can't found it in Applications/Postgres.app/Contents/Versions/14/lib/, where to find libqsqlpsql.dylib or how to make it generated automaticly by qt?

SGaist

Might be a silly question but are you using the SQL module in your test app ?

juneleung

@SGaist yes i have add sql in qt.

QT += sql

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

The release package installed in local Macbook can open and link to sqldatabase, but move to another mac will get wrong driver.

Does I miss any steps when release packages?

artwaw

@juneleung said in MySQL driver detected but not loading on MacOS:

I don't have the libqsqlpsql.dylib in sqldrivers folder, and i can't found it in Applications/Postgres.app/Contents/Versions/14/lib/, where to find libqsqlpsql.dylib or how to make it generated automaticly by qt?

That what's macdeployqt should do, if memory serves. Important - can't my be with option App Store compatible. It is Qt plugin, should be deployed.

juneleung

@artwaw said in MySQL driver detected but not loading on MacOS:

That what's macdeployqt should do, if memory serves. Important - can't my with option App Store compatible. It is Qt plugin, should be deployed.

my macdeployqt step is :
macdeployqt /Users/test/Build/build-test-Desktop_Qt_5_15_2_clang_64bit-Release/test.app -dmg

any args should added to generate libqsqlpsql.dylib? or any step to setup at release mode?
Thanks!

artwaw

@juneleung Pls check your package under path:

ls test.app/Contents/PlugIns/sqldrivers
libqsqlite.dylib	libqsqlodbc.dylib	libqsqlpsql.dylib

That's how it should be after the deploy.
You can pass verbose=2 to have more data on how deployment goes (I recommend together with overwrite option, this way you'll be able to see every copied file). Caution, this would be very verbose.

juneleung

@artwaw
Thanks for your guide and I have generated the dylib successfully. :)

in the /Applications/Postgres.app/Contents/Versions/14/lib/, my libpq.5.dylib looks is an alias, so i copy the libpq.5.14.dylib to /Users/test/Build/build-GiraffeL-Desktop_Qt_5_15_2_clang_64bit-Release/test.app/Contents/Frameworks/libpq.5.14.dylib, is it correct to copy libpq.5.14.dylib or I should copy the libpq.5.dylib alias file .

and before running with :

cp /Applications/Postgres.app/Contents/Versions/14/lib/libpq.5.14.dylib /Users/test/Build/build-test-Desktop_Qt_5_15_2_clang_64bit-Release/test.app/Contents/Frameworks/

install_name_tool -change /Applications/Postgres.app/Contents/Versions/9.6/lib/libpq.5.dylib @executable_path/../Frameworks/libpq.5.14.dylib /Users/test/Build/build-test-Desktop_Qt_5_15_2_clang_64bit-Release/test.app/Contents/PlugIns/sqldrivers/libqsqlpsql.dylib

**install_name_tool -change libpq.5.dylib @executable_path/../Frameworks/libpq.5.14.dylib /Users/test/Build/build-test-Desktop_Qt_5_15_2_clang_64bit-Release/test.app/Contents/MacOS/test**

I use otool to check test.app/Contents/MacOS/test

otool -L test.app/Contents/MacOS/test

but it looks don't have the libpq.5.dylib in the print list.
is it correct to install_name_tool the libpq.5.dylib path for the test.app/Contents/MacOS/test? or another file?

artwaw

I used Contents/Frameworks path as it seems to be aligned with what macOS is expecting.
if you look at my example deploy script above you'll see that I copy libpq* files there.
Then install_name_tool of course.

If you check otool (and my script) you'll see exactly what needs to linked to what.

SGaist

@artwaw is correct, the application bundle has rules with regards to what goes where. See the Apple documentation.

artwaw

@SGaist Yes. I forgot to link this, thank you.

juneleung

@artwaw

Sorry, maybe I didn't explain clearly.

I have copied the libpq.5.dylib to the framework folder,

In your previous code

install_name_tool -change libpq.5.dylib @executable_path/../Frameworks/libpq.5.dylib appName.app/Contents/MacOS/appName

it looks like changing the link path in the app file, is this pointing to the app? Or point to another file? Cause I checked the app file (test.app/Contents/MacOS/test) by otool, but in the printed link list, I don't see any information about libpq.5 .dylib part, is this normal?

because there is no part of libpq.5.dylib, so I modified install_name_tool seems doesn't work either?