Question

how can I write a NOT IN in named scope syntax? For example, User :has_many Photos, how can I define:

User.has_no_photo

and returns all users who are not in the Photo model? thanks!

Answer 1

named_scope :has_no_photos, :conditions => [ 
  "id NOT IN ?", 
  Photo.all(:select => "distinct user_id").map(&:user_id).map(&:to_i)
]

I assume you have a standard “Photo.belongs_to :user” association, and integer keys