code: def get_upload_path(instance, filename):
      
      if not instance.name:
          instance.name = filename  # set original filename
      date = timezone.now().date()
      filename = '{name}.{ext}'.format(name=uuid4().hex,
                                       ext=filename.split('.')[-1])
  
      return os.path.join('post_office_attachments', str(date.year),
                          str(date.month), str(date.day), filename)
docs: Overriding to store the original filename