module API module Helpers module Pagination def paginate(relation) relation = add_default_order(relation) relation.page(params[:page]).per(params[:per_page]).tap do |data| add_pagination_headers(data) end end private def add_pagination_headers(paginated_data) header 'X-Total', paginated_data.total_count.to_s header 'X-Total-Pages', total_pages(paginated_data).to_s header 'X-Per-Page', paginated_data.limit_value.to_s header 'X-Page', paginated_data.current_page.to_s header 'X-Next-Page', paginated_data.next_page.to_s header 'X-Prev-Page', paginated_data.prev_page.to_s header 'Link', pagination_links(paginated_data) end def pagination_links(paginated_data) request_url = request.url.split('?').first request_params = params.clone request_params[:per_page] = paginated_data.limit_value links = [] request_params[:page] = paginated_data.prev_page links << %(<#{request_url}?#{request_params.to_query}>; rel="prev") if request_params[:page] request_params[:page] = paginated_data.next_page links << %(<#{request_url}?#{request_params.to_query}>; rel="next") if request_params[:page] request_params[:page] = 1 links << %(<#{request_url}?#{request_params.to_query}>; rel="first") request_params[:page] = total_pages(paginated_data) links << %(<#{request_url}?#{request_params.to_query}>; rel="last") links.join(', ') end def total_pages(paginated_data) # Ensure there is in total at least 1 page [paginated_data.total_pages, 1].max end def add_default_order(relation) if relation.is_a?(ActiveRecord::Relation) && relation.order_values.empty? relation = relation.order(:id) end relation end end end end