rails pagination headers

api_paginate.rb

module ApiPagination
  protected

  def api_paginate(collection, options = {})
    links = (headers['Link'] || "").split(',').map(&:strip)
    url   = request.original_url.sub(/\?.*$/, '')
    pages = pages_from(collection)

    pages.each do |k, v|
      new_params = request.query_parameters.merge(:page => v)
      links << %(<#{url}?#{new_params.to_param}>; rel="#{k}")
    end

    headers['Link']  = links.join(', ') unless links.empty?
    headers['Total'] = [collection.total_entries]
    headers['X-Pagination-Total-Results'] = [collection.total_entries]
  end

  def pages_from(collection)
    {}.tap do |pages|
      if collection.previous_page
        pages[:prev]  = collection.current_page - 1
      end

      if collection.next_page
        pages[:next] = collection.current_page + 1
      end
    end
  end
end