FilePathField - Django 3.x allowed "path" as callable

[chakibBH]

Hi,

First post here, so I don't know if it's the correct channel for this kind of issue.
Sorry if it's not.

Since v 3.0 we can set the "path" attribute as a callable in a models.fields.FilePathField(),
as discussed here:
https://code.djangoproject.com/ticket/29529

and documented here:
https://docs.djangoproject.com/en/3.0/ref/models/fields/#django.db.models.FilePathField.path

The commit adding this feature can be found here:
django/django@ef082eb

DRF documentation stating this field corresponds to django.forms.fields.FilePathField()
(https://www.django-rest-framework.org/api-guide/fields/#filepathfield)
Also we can see how the Django's form field is used by DRF's serializer field:
https://github.com/encode/django-rest-framework/blob/master/rest_framework/fields.py#L1504

I have an issue in the case where path is defined as a callable in my model field,
when os.scandir(self.path) is called (as showed in https://github.com/django/django/blob/stable/3.2.x/django/forms/fields.py#L1126). I 'm facing this explicit error:
"scandir: path should be string, bytes, os.PathLike, integer or None, not function"

I tried to reach the djangoproject team and opened a ticket:
https://code.djangoproject.com/ticket/33254
To see if this behaviour is intendeded.

So my questionis: Should "path" attribute be checked before send to django.forms.fields.FilePathField() to avoid the scandir error ?

Something similar to what they have done whene they allowed "path" to be a callabel:

class FilePathField(ChoiceField):
    default_error_messages = {
        'invalid_choice': _('"{input}" is not a valid path choice.')
    }
    def __init__(self, path, match=None, recursive=False, allow_files=True,
                 allow_folders=False, required=None, **kwargs):
        # Defer to Django's FilePathField implementation to get the
        # valid set of choices.

        path = path() if callable(path) else path
        
        field = DjangoFilePathField(
            path, match=match, recursive=recursive, allow_files=allow_files,
            allow_folders=allow_folders, required=required
        )
        kwargs['choices'] = field.choices
        super().__init__(**kwargs)