foodsoft/app/models/concerns/find_each_with_order.rb

# @see https://gist.github.com/virtualstaticvoid/8705533
module FindEachWithOrder
  extend ActiveSupport::Concern

  class_methods do
    def find_each_with_order(options = {}, &block)
      find_in_batches_with_order(options) do |records|
        records.each(&block)
      end
    end

    # NOTE: any limit() on the query is overridden with the batch size
    def find_in_batches_with_order(options = {})
      options.assert_valid_keys(:batch_size)

      relation = self

      start = 0
      batch_size = options.delete(:batch_size) || 1000

      relation = relation.limit(batch_size)
      records = relation.offset(start).to_a

      while records.any?
        records_size = records.size

        yield records

        break if records_size < batch_size

        # get the next batch
        start += batch_size
        records = relation.offset(start).to_a
      end
    end
  end
end