The value obtained by
django request.session.session_key is
if not request.session.session_key: request.session.create() session_id = request.session.session_key
SessionStore.create() is used to create a new session (
session_key=None that is not loaded from the session store).
save() is used to save the existing session (that is, the session loaded from the session store).
save() for a new session may also be effective, but the possibility of session_key conflicting with an existing session is very small.
save() and loops until the
session_key is generated unused.