If I set every user's session[:user_id] = user.id (model object.id)
saved it in activerecord table sessions, how would I extract
session[:user_id] from the sessions table, so I can display who's
with difficulty - the database just contains a Marshal.dump
representation of the data, so you can't query for it.
You'd probably be better off just updating the users table with a
'last_seen_at' timestamp. Or add a user_id column to the sessions
table (access it via session.model if i recall correctly).