How to get the default application mapped to a file extention in windows using Python

Question

I would like to query Windows using a file extension as a parameter (e.g. ".jpg") and be returned the path of whatever app windows has configured as the default application for this file type.

Ideally the solution would look something like this:

from stackoverflow import get_default_windows_app

default_app = get_default_windows_app(".jpg")

print(default_app)
"c:\path\to\default\application\application.exe"

I have been investigating the winreg builtin library which holds the registry infomation for windows but I'm having trouble understanding its structure and the documentation is quite complex.

I'm running Windows 10 and Python 3.6.

Does anyone have any ideas to help?

Answer 1

The registry isn't a simple well-structured database. The Windows shell executor has some pretty complex logic to it. But for the simple cases, this should do the trick:

import shlex
import winreg

def get_default_windows_app(suffix):
    class_root = winreg.QueryValue(winreg.HKEY_CLASSES_ROOT, suffix)
    with winreg.OpenKey(winreg.HKEY_CLASSES_ROOT, r'{}\shell\open\command'.format(class_root)) as key:
        command = winreg.QueryValueEx(key, '')[0]
        return shlex.split(command)[0]

>>> get_default_windows_app('.pptx')
'C:\\Program Files\\Microsoft Office 15\\Root\\Office15\\POWERPNT.EXE'

Though some error handling should definitely be added too.