Building QMYSQL / MARIADB with Qt 6.3.0

[SGaist]

Hi and welcome to devnet,

If memory serves well, the online installer also provides the option to install cmake.

As for the loading issue, start your application with the QT_DEBUG_PLUGINS environment variable set to 1. You can do that in the Run part of the Project panel.

[AnUnusualRemote]

Sorry, I have done that correct, I just found it.
That doesn't seem to have done anything, in fact it was already set towards 1 when I checked. The online installer also seems to have CMake 3.21.1 64-bit showing as installed under Developer and Designer Tools.

[SGaist]

If the environment variable is properly defined, you should have a dump of information about the plugins being loaded and why they failed.

[AnUnusualRemote]

@SGaist
I'm assuming this would be

{
    "IID": "org.qt-project.Qt.QSqlDriverFactoryInterface",
    "MetaData": {
        "Keys": [
            "QMYSQL",
            "QMARIADB"
        ]
    },
    "archlevel": 0,
    "className": "QMYSQLDriverPlugin",
    "debug": true,
    "version": 393728
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("QMYSQL", "QMARIADB")
qt.core.plugin.factoryloader: looking at "C:/Qt/6.3.0/mingw_64/plugins/sqldrivers/qsqlodbc.dll"
qt.core.plugin.loader: Found metadata in lib C:/Qt/6.3.0/mingw_64/plugins/sqldrivers/qsqlodbc.dll, metadata=

Along with this line.

qt.core.library: "C:/Qt/6.3.0/mingw_64/plugins/sqldrivers/qsqlmysql.dll" cannot load: Cannot load library C:\Qt\6.3.0\mingw_64\plugins\sqldrivers\qsqlmysql.dll: The specified module could not be found.
qt.core.plugin.loader: QLibraryPrivate::loadPlugin failed on "C:/Qt/6.3.0/mingw_64/plugins/sqldrivers/qsqlmysql.dll" : "Cannot load library C:\\Qt\\6.3.0\\mingw_64\\plugins\\sqldrivers\\qsqlmysql.dll: The specified module could not be found."

Since that's the sqldriver folder, I checked. Results are above. I can only guess that there's a missing .debug file, or that the .dll is incompatible with Qt for some reason.

[SGaist]

Maybe a silly question but are you sure that the dll you have now is from the correct compiler ?

[AnUnusualRemote]

@SGaist
Very likely that it may not be from the right compiler, I could not compile it, so I asked a friend to instead. I suppose my best option right now is to try and build everything myself.

[SGaist]

You do not have to rebuild everything. Just the plugin.

[AnUnusualRemote]

@SGaist
I'm not entirely sure how to build it based on the documentation. I have the files for MariaDB location in the right folders when it comes to the .lib, .dll and .h files. Problem is that I'm not sure where I should be for building the plugins when it comes to the command prompt.

mkdir build-sqldrivers
cd build-sqldrivers

qt-cmake -G Ninja <qt_installation_path>\Src\qtbase\src\plugins\sqldrivers -DCMAKE_INSTALL_PREFIX=<qt_installation_path>\<platform> -DMySQL_INCLUDE_DIR="C:\mysql-8.0.22-winx64\include" -DMySQL_LIBRARY="C:\mysql-8.0.22-winx64\lib\libmysql.lib"
cmake --build .
cmake --install .

I'm not entirely sure where I should be located within my file structure to build the plugins, inside of the Qt 6.3.0 folder? The bin folder of the Qt 6.3.0 folder perhaps? qt-cmake doesn't seem to be recgonised as a command, so I assume it's located somewhere inside of the Qt folder.

'qt-cmake' is not recognized as an internal or external command, operable program or batch file.

I also do not know what Ninja refers to within the command. Do I need to install this too?

[SGaist]

Try with just cmake in place of qt-cmake.

As for Ninja, it's also available through the installer.

[AnUnusualRemote]

@SGaist
Since I'm using and building for MariaDB

qt-cmake -G Ninja <qt_installation_path>\Src\qtbase\src\plugins\sqldrivers -DCMAKE_INSTALL_PREFIX=<qt_installation_path>\<platform> -DMySQL_INCLUDE_DIR="C:\mysql-8.0.22-winx64\include" -DMySQL_LIBRARY="C:\mysql-8.0.22-winx64\lib\libmysql.lib"

The DMySQL and DMySQL_LIBRARY should probably be replaced with DMariaDB or some equivalent, correct? The locations will change, but obviously those are where I've installed the relevant files.

[SGaist]

From memory, no, MariaDB is a drop in replacement so it would not make sense to complicate the build system for that.