[web2py] if user going logged out

[pk]

hi

one question:
def user():
    if request.args(0) == 'logout':
        query
    return dict(form=auth())
what is if i need there the auth.user.id???

this is my query:
db(db.nao.userid==auth.user.id).update(db.nao.ipadress="")

is this possible? if not how can i do this?

peter