Why are imports not visible?

Question

Django

There are a bunch of applications.
In one of the applications in models.py:

# -*- coding: utf-8 -*-
import os
from django.conf import settings

.....
#Имеется вот такой класс для загрузки изображения

#BaseModel - абстракт (описывает только привязку к юзеру)
class Image(BaseModel): 
    def file_uploads_to(instance, filename):
        #from django.conf import settings
        #import os
        file_name = '/'.join(['dir', instance.user.id, 'image', filename])
        file_folder = os.path.join(settings.MEDIA_ROOT, 'dir/%s/image/' % instance.user.id,)
        if not os.path.exists(file_folder):
            os.makedirs(file_folder)
        return file_name

    text = models.TextField('_(Info)', max_length=1000, blank=False, null=True, default='')
    image = models.ImageField('_(Image)', upload_to=file_uploads_to, blank=True)

    class Meta:
                     .....

Until you forcefully import settings and os in the file_uploads_to method, it says that they are NoneType.
In other models of other applications, everything works as expected. What could be causing this behaviour?
The models are all similar in structure, there are no decors and overrides anywhere. Simple.

Answer 1

from django.conf.settings import MEDIA_ROOT


......
        file_name = os.path.join('dir', instance.user.id, 'image', filename)
        file_folder = os.path.join(MEDIA_ROOT, 'dir', instance.user.id, 'image')