ruby on rails 3 - default scope with condition -

i using rails 3.2.13 , ruby 1.9.3. having 3 models :- email user

i have 2 roles users => publisher or subscriber

i want know how can in rails if want have emails subscribers , publishers. such as, write email.find(####).publishers email.find(####).subscribers

without having different table subs , pubs. also, have has many through relationship between email , user.

also, want achieve default scope email.publishers.approved? should visible users others should hidden.

the way have field 'role' in emailuser model.

and in email model add following 2 methods:

def publishers   self.users.where(:email_users=>{:role=>'publishers'}) end  def subscribers   self.users.where(:email_users=>{:role=>'subscribers'}) end