Rails: three most recent comments with unique users
- by Dennis Collective
what would I put in the named scope :by_unique_users so that I can do Comment.recent.by_unique_users.limit(3), and only get one comment per user?
class User
has_many :comments
end
class Comment
belongs_to :user
named_scope :recent, :order => 'comments.created_at DESC'
named_scope :limit, lambda { |limit| {:limit => limit}}
named_scope :by_unique_users
end
on sqlite named_scope :by_unique_user, :group = "user_id" works,
but makes it freak out on postgres, which is deployed on production
PGError: ERROR: column "comments.id" must appear in the GROUP BY clause or be used in an aggregate function
