@House.find(:first).users - [current_user]
in your controller somewhere.
I would put it in the models if i was to use a method like this
class User < AR::Base
house.users - [self]
the problem with this aproach is that you cant do anything with the
rooomates apart from seeing them. you have no User.roomates <<
user.new or any of the Ar methods.
So... I would put it into the association, having house as a join
table between Users and Users... something on the lines (and note i
say on the lines because you would probably have to change the
associations you have to accomplish this.) of:
has_many :roomates, :through => :house, :class_name => 'User'