translate postrgreSQL query to ActiveRecord-CodePudding

i would like to translate this query to an active record statement to get things done in a more rails way although it could be executed as it is with ActiveRecord::Base.connection.execute

have been struggling to achieve it, any help on this will be much appreciated!

"select distinct on (papers.id) boxes.created_at, boxes.id from papers left join boxes on paper.id = boxes.id order by paper.id, boxes.created_at DESC;"

CodePudding user response：

distinct on is not supported with a dedicated method in ActiveRecord, therefore you have to be more verbose:

Box
  .select('select distinct on (papers.id) boxes.created_at, boxes.id')
  .joins(:paper)
  .order('paper.id, boxes.created_at DESC')

Box and joins(:paper) of course only works when you have your ActiveRecord models and associations properly set up.