search for: pair_id

I have a time tracking app where (pseudo-code) Client has_many Task has_many TimeRecord TimeRecord start_at, :datetime end_at, :datetime What I''m trying to do (and I have done using find_by_sql in the past) is get a sum of the timespan given by ended_at - begun_at for each client. Is it naive to imagine that AR''s calculations will span relations to provide a grouped

...this: create_table :stereos, :force => true do |t| t.column :type, :string # common attributes t.column :photo_name, :string t.column :created_at, :datetime t.column :updated_at, :datetime t.column :order_id, :integer # attributes for type=Photo t.column :date_taken, :datetime t.column :pair_id, :integer # attributes for type=Preview t.column :authorized_by_id, :integer t.column :photo1_id, :integer t.column :photo2_id, :integer # attributes for type=Final t.column :photo1_id, :integer t.column :photo2_id, :integer end Now for the hierarchy of model objects: class Stereo < Active...