Rails - Apr 2006 - Finding items that aren''t associated

Thanks to some advice from the list earlier, I now have a Permission 
model that links User and Thing (using has_many and :through).

I can easily get the list of current users by doing the following:

@thing = Thing.find(params[:id])
@current_users = @thing.users

But in my view, I want to construct a select of those users that
haven''t
had permissions added, so they can be added.  I''ve tried some pretty 
stupid stuff like subtracting @thing.users from User.find :all, but this 
doesn''t seem to work.

What is the easiest way of picking out all users that aren''t currently 
associated with the given thing?  Then, I''ll create a multi-select and 
try to work out how to iterate through all the selected ones and add 
their permissions.

Thanks.

-- 
Posted via http://www.ruby-forum.com/.