I have a has_one association which is used for extending an entity,
class User < ActiveRecord::Base
class UserEx < …
#country, city, street…
The UserEx entity is optional (there are users without extended info).
My problem is: if u is a User object which has no user_ex extension,
activerecord always tries to fetch the UserEx object whenever I
write u.user_ex (it thinks user_ex isn’t yet loaded). I also want to
include the user_ex association when I load some users. What is
the simplest way to do this?