helper to iterate all by pagination using kaminari

each_by_page.rb

# Probably should investigate how to chain this with scopes
# Also assumes mongoid with a default _id field, and the order_by method

class MyModel
  def self.each_by_page(options = {})
    per = options[:per] || 25
    order_by = options[:order_by] || [:_id, 1]
    i = 1
    until (current_page = self.order_by(order_by).page(i).per(per)).empty?
      current_page.each do |obj|
        yield obj
      end
      i = i + 1
    end
  end
end

usage.rb

MyModel.each_by_page(per: 1000) do |obj|
  # ...
end