educoder/lib/tasks/course_board_message_count.rake

namespace :course_board do
  desc 'transfer children message to root message board'
  task children_message_transfer: :environment do
    Board.find_each do |board|
      logger("Current transfer board id: #{board.id} ~")

      root_subquery = board.messages.where(parent_id: nil).reorder(nil).pluck(:id)
      if root_subquery.present?
        children_subquery = Message.where(parent_id: root_subquery).reorder(nil).pluck(:id)
        if children_subquery.present?
          second_children_subquery = Message.where(parent_id: children_subquery).reorder(nil).pluck(:id)

          ids = children_subquery.concat(second_children_subquery).uniq
          Message.where(id: ids).update_all(board_id: board.id)
        end
      end

      Board.reset_counters(board.id, :messages)
      logger("transfer success ~")
    end
  end

  def logger(msg)
    puts msg
  end
end