500 error with upload_to function

[lorddaedra]

Please, check my code. Did I make some mistake? File had been uploaded to directory named functools.partial(<function upload_to_with_prefix at 0x3e529513bca0>, 'mymod ... And, of course, I can't save document later, 500 error.

Python 3.9 Django 3.2

def upload_to_with_prefix(instance, filename, prefix: str) -> str:
    filename_parts = filename.split('.')
    extension = '.' + filename_parts[-1] if len(filename_parts) > 1 else ''
    return ''.join([prefix, str(uuid.uuid4().int), extension.lower()])

class MyModel(models.Model):
    video = AsyncFileField("video", upload_to=partial(upload_to_with_prefix, prefix='mymodel_video/'))

[lorddaedra]