Filechooser on mac: using path, crashes python

MacOS 10.14.6

using the path parameter causes python to crash (not just the app). Using the use_extensions with path causes an uncaught exception.

Test case:

from pathlib import Path

from kivy.app import App
from kivy.lang.builder import Builder
from plyer import filechooser

kv = '''
BoxLayout:
    orientation: 'vertical'
    Button:
        text: 'Test: Open, filters=["*.pdf"]; this will crash python'
        on_release: app.ft.open(filters=['*.pdf'])
    Button:
        text: 'Test: Open, filters=["*.pdf"] use_extensions=True; throws exception '
        on_release: app.ft.open(filters=['*.pdf'], use_extensions=True)
    Button:
        text: 'Test: Open, filters=[] this will work as expected'
        on_release: app.ft.open()
    Label:
        text: 'plyer.filechooser.open_file() with a filter will crash on mac'
'''


class FileTest:
    def __init__(self):
        self.file_name = ''

    def open(self, **kwargs):
        filechooser.open_file(title='Open Patch File',
                              on_selection=self._open_selection, **kwargs)

    def _open_selection(self, selection):
        try:
            self.file_name = Path(selection[0]).name
        except (ValueError, IndexError):  # The user did not select a file
            print('open canceled')
        else:
            print(f'open file: {self.file_name}')


class PlyerFilechooserTestApp(App):
    ft = FileTest()

    def build(self):
        return Builder.load_string(kv)


if __name__ == '__main__':
    PlyerFilechooserTestApp().run()

[Mulugruntz]

Found the issue! I’ll do a PR.

[Mulugruntz]

The thing was that objc_arr was expecting positional arguments. https://github.com/kivy/pyobjus/blob/3f6314152ea850bff8a218fb3dbc4df22431a4f2/pyobjus/pyobjus_types.pxi#L371

And the list was given as an argument. In Objective-C, there’s this thing where when you initialize with a list, the last element must have nil. And objc_arr is adding a None at the end of the positional arguments.

So, instead of having ('jpg', 'JPG', None), it had (['jpg', 'JPG'], None). The setAllowedFileTypes() method was expecting to work on strings and received a list. Crash.