get_user_id_by_session_key.py

import importlib

from django.conf import settings
from django.contrib.auth import SESSION_KEY


def get_id_by_session_key(session_key):
    """
    Returns user identifier by session_key
    """
    session_store_module = importlib.import_module(settings.SESSION_ENGINE)
    store = session_store_module.SessionStore(session_key=session_key)
    return User._meta.pk.to_python(store[SESSION_KEY])