How do I store desktop application data in a cross platform way for python?

Question

I have a python desktop application that needs to store user data. On Windows, this is usually in %USERPROFILE%\Application Data\AppName\, on OSX it's usually ~/Library/Application Support/AppName/, and on other *nixes it's usually ~/.appname/.

There exists a function in the standard library, os.path.expanduser that will get me a user's home directory, but I know that on Windows, at least, "Application Data" is localized into the user's language. That might be true for OSX as well.

What is the correct way to get this location?

UPDATE: Some further research indicates that the correct way to get this on OSX is by using the function NSSearchPathDirectory, but that's Cocoa, so it means calling the PyObjC bridge...

Answer 1

Well, I hate to have been the one to answer my own question, but no one else seems to know. I'm leaving the answer for posterity.

APPNAME = "MyApp"
import sys
from os import path, environ
if sys.platform == 'darwin':
    from AppKit import NSSearchPathForDirectoriesInDomains
    # http://developer.apple.com/DOCUMENTATION/Cocoa/Reference/Foundation/Miscellaneous/Foundation_Functions/Reference/reference.html#//apple_ref/c/func/NSSearchPathForDirectoriesInDomains
    # NSApplicationSupportDirectory = 14
    # NSUserDomainMask = 1
    # True for expanding the tilde into a fully qualified path
    appdata = path.join(NSSearchPathForDirectoriesInDomains(14, 1, True)[0], APPNAME)
elif sys.platform == 'win32':
    appdata = path.join(environ['APPDATA'], APPNAME)
else:
    appdata = path.expanduser(path.join("~", "." + APPNAME))

Answer 2

There's a small module available that does exactly that:

https://pypi.org/project/appdirs/

Answer 3

You can try to use QSettings from Qt. You can obtain the path to your MyCompany/MyApp.ini file this way:

from PySide.QtCore import QSettings, QCoreApplication

QSettings.setDefaultFormat(QSettings.IniFormat)
QCoreApplication.setOrganizationName("MyCompany")
QCoreApplication.setApplicationName("MyApp")
settings = QSettings()
print(settings.fileName())

Alternatively, without changing any global state:

QSettings(
    QSettings.IniFormat, QSettings.UserScope,
    "MyCompany", "MyApp"
).fileName()

On Win7 you get something like:

C:\Users\MyUser\AppData\Roaming\MyCompany\MyApp.ini

On Linux (may vary):

/home/myuser/.config/MyCompany/MyApp.ini

I don't know the possible results for OSX (but I'd like to).

QSettings functionallity seem to be nice until you want to use registerFormat, which is not available in PySide, so there is no easy way to use YAML or JSON writers for settings.

Answer 4

Well, for Windows APPDATA (environmental variable) points to a user's "Application Data" folder. Not sure about OSX, though.

The correct way, in my opinion, is to do it on a per-platform basis.