Postgresql driver is not found

[alxdef]

@SGaist
Here the part of application output about DLL load failure:

Got keys from plugin meta data ("QPSQL7", "QPSQL")
QFactoryLoader :: QFactoryLoader () checking directory path "…/ build-MCS-Desktop_Qt_5_15_2_MinGW_64_bit-Debug / Shell / debug / sqldrivers" …
Cannot load library C: \ Qt \ 5.15.2 \ mingw81_64 \ plugins \ sqldrivers \ qsqlpsql.dll: The specified module could not be found.
QLibraryPrivate :: loadPlugin failed on "C:/Qt/5.15.2/mingw81_64/plugins/sqldrivers/qsqlpsql.dll": "Cannot load library C: \\ Qt \\ 5.15.2 \\ mingw81_64 \\ plugins \\ sqldrivers \\ qsqlpsql.dll: The specified module could not be found. "
QSqlDatabase: QPSQL driver not loaded
QSqlDatabase: available drivers: QSQLITE QODBC QODBC3 QPSQL QPSQL7

Tell me what additional information is needed?

[SGaist]

Just remembered something, check that you have also copied the dependencies of the PostgreSQL .dll.

[alxdef]

@SGaist
Am I on the right way? Which of them should be added in project executable folder?

[SGaist]

The OpenSSL related

[alxdef]

@SGaist said in Postgresql driver is not found:

The OpenSSL related

Not works.

[SGaist]

Then run Dependency Walker on these.
The next likely candidate is the VC runtime dll.

[alxdef]

@SGaist

I think that library is not in business.

[SGaist]

I meant that you should run Dependency Walker on the OpenSSL dlls and that it would have likely been the VC runtime missing.

[alxdef]

@SGaist

It looks like infinite loop…

[SGaist]

Did you copy the VC runtime in the same folder as the OpenSSL library ?

[Christian Ehrlicher]

@alxdef Your first screenshot tells you that libstdc++-6.dll is missing.

[SGaist]

@Christian-Ehrlicher said in Postgresql driver is not found:

@alxdef Your first screenshot tells you that libstdc++-6.dll is missing.

Arf ! I missed that one. Good catch :-)

[alxdef]

@Christian-Ehrlicher

These libs are present in my app executable folder:

sqldrivers\qsqlpsql.dll
platforms\qwindows.dll
vcruntime140.dll
Qt5Sql.dll
Qt5Core.dll
msvcrt.dll
libstdc++-6.dll
libssl-1_1-x64.dll
libpq.dll
libintl-8.dll
libcrypto-1_1-x64.dll

[alxdef]

So there are no ideas…

[Bonnie]

Did you get libpq from the official site? I've just had a try.
I think it is probably due to the file you were all ignoring: libintl-8.dll --> it depends on libiconv-2.dll, which you didn't copy.
When you use Dependency Walker on libpq.dll, check all the yellow icons, not only in the upper part tree, but also in the lower part list (those are all the dlls recursively)...
But there may also be some many "false alarms", especially those dlls needed by system dlls / vc runtimes (e.g.: api-ms-...), you'll need to distinguish them by yourself.
I mainly check those start with "lib" (MinGW style) and "q" (Qt libs).
Or you can manually expand all the tree items recursively, just skip when it is a system / vc runtime.

[alxdef]

@Bonnie
Thanks for advice. Now application debug output looks like this:

Got keys from plugin meta data ("QPSQL7", "QPSQL")
loaded library "…/debug/sqldrivers/qsqlpsql.dll"
QFactoryLoader::QFactoryLoader() checking directory path "…/debug/accessible" ...
QFactoryLoader::QFactoryLoader() checking directory path "…/debug/accessiblebridge" ...
QLibraryPrivate::unload succeeded on "…/debug/sqldrivers/qsqlpsql.dll" 
QLibraryPrivate::unload succeeded on "…/debug/platforms/qwindows.dll" 
21:31:17: *.exe exited with code 0

But I still catch "Driver not loaded" using this code:

if (!this->app_conn.isValid())
{
  //…
}

if (!this->app_conn.open())
{
  //…
}

[SGaist]

Can you show the code your are actually using to setup the database ?

The output you show does not present any error quite the contrary.

[alxdef]

@SGaist

this->app_conn = QSqlDatabase();

  this->app_conn.addDatabase(this->db_type);
  this->app_conn.setDatabaseName(this->db_name);
  this->app_conn.setHostName(this->db_host);
  this->app_conn.setPort(this->db_port);
  this->app_conn.setUserName(this->user_name);
  this->app_conn.setPassword(this->user_password);

this->db_type is "QPSQL".

[SGaist]

You are using QSqlDatabase in the wrong manner.

addDatabase is a static member, you are manipulating an invalid object.

As the QSqlDatabase warns about: do not store local variables of that type. The class already provides everything needed to handle the objects you create from it.

[alxdef]

@SGaist said in Postgresql driver is not found:

QSqlDatabase

Many thanks! Connected Ok.