How to use relative file paths in Lazarus

I'm creating a simple CRM in Lazarus with an SQLite backend but I can't figure out how to give Lazarus the file path to the database file relativly. This is needed for when I publish the app as I won't know what the full file path is on different target computers.

In Delphi, I know you can just put the file name of the database (with no further file path) in the connection string property of the connector and it'll work as long as that file is in the project folder but the equivalent in Lazarus (DatabaseName) doesn't allow relative file paths to be put there.

There are supposedly solutions on the Lazarus Forum, but they look complicated and I'm not understanding them.

Is it not possible to do this in a simple way on Lazarus, in which case am I better to try to run Python from Lazarus to get an absolute path from a relative path?

I need the relative paths to work on both Windows and MacOS

For me that never worked universally in Delphi either, though sometimes depending on how you open the project it might work in the IDE . It might also depend on what you use as database components.

Anyway, you can find the working dir on Windows using

sExePath := ExtractFilePath(paramstr(0));

for console programs, while for for GUI apps you can do

sExePath := ExtractFilePath(Application.ExeName);

You can then craft the path using

includetrailingpathdelimiters(sExepath)+relativepath

and set the property on startup.

added later:

Note that in the past I let my applications change the working directory to this path on startup. I abandoned that approach since file->open menus could change working directory, making the result fragile So in the end I recoded all path crafting to be relative to a directory that I establish at start-up