diff options
Diffstat (limited to 'lib/gitlab/pagination')
| -rw-r--r-- | lib/gitlab/pagination/keyset/header_builder.rb | 1 | ||||
| -rw-r--r-- | lib/gitlab/pagination/keyset/paginator.rb | 176 | ||||
| -rw-r--r-- | lib/gitlab/pagination/keyset/simple_order_builder.rb | 2 |
3 files changed, 178 insertions, 1 deletions
diff --git a/lib/gitlab/pagination/keyset/header_builder.rb b/lib/gitlab/pagination/keyset/header_builder.rb index 69c468207f6..888d93d5fe3 100644 --- a/lib/gitlab/pagination/keyset/header_builder.rb +++ b/lib/gitlab/pagination/keyset/header_builder.rb @@ -13,7 +13,6 @@ module Gitlab def add_next_page_header(query_params) link = next_page_link(page_href(query_params)) - header('Links', link) header('Link', link) end diff --git a/lib/gitlab/pagination/keyset/paginator.rb b/lib/gitlab/pagination/keyset/paginator.rb new file mode 100644 index 00000000000..2ec4472fcd6 --- /dev/null +++ b/lib/gitlab/pagination/keyset/paginator.rb @@ -0,0 +1,176 @@ +# frozen_string_literal: true + +module Gitlab + module Pagination + module Keyset + class Paginator + include Enumerable + + module Base64CursorConverter + def self.dump(cursor_attributes) + Base64.urlsafe_encode64(Gitlab::Json.dump(cursor_attributes)) + end + + def self.parse(cursor) + Gitlab::Json.parse(Base64.urlsafe_decode64(cursor)).with_indifferent_access + end + end + + FORWARD_DIRECTION = 'n' + BACKWARD_DIRECTION = 'p' + + UnsupportedScopeOrder = Class.new(StandardError) + + # scope - ActiveRecord::Relation object with order by clause + # cursor - Encoded cursor attributes as String. Empty value will requests the first page. + # per_page - Number of items per page. + # cursor_converter - Object that serializes and de-serializes the cursor attributes. Implements dump and parse methods. + # direction_key - Symbol that will be the hash key of the direction within the cursor. (default: _kd => keyset direction) + def initialize(scope:, cursor: nil, per_page: 20, cursor_converter: Base64CursorConverter, direction_key: :_kd) + @keyset_scope = build_scope(scope) + @order = Gitlab::Pagination::Keyset::Order.extract_keyset_order_object(@keyset_scope) + @per_page = per_page + @cursor_converter = cursor_converter + @direction_key = direction_key + @has_another_page = false + @at_last_page = false + @at_first_page = false + @cursor_attributes = decode_cursor_attributes(cursor) + + set_pagination_helper_flags! + end + + # rubocop: disable CodeReuse/ActiveRecord + def records + @records ||= begin + items = if paginate_backward? + reversed_order + .apply_cursor_conditions(keyset_scope, cursor_attributes) + .reorder(reversed_order) + .limit(per_page_plus_one) + .to_a + else + order + .apply_cursor_conditions(keyset_scope, cursor_attributes) + .limit(per_page_plus_one) + .to_a + end + + @has_another_page = items.size == per_page_plus_one + items.pop if @has_another_page + items.reverse! if paginate_backward? + items + end + end + # rubocop: enable CodeReuse/ActiveRecord + + # This and has_previous_page? methods are direction aware. In case we paginate backwards, + # has_next_page? will mean that we have a previous page. + def has_next_page? + records + + if at_last_page? + false + elsif paginate_forward? + @has_another_page + elsif paginate_backward? + true + end + end + + def has_previous_page? + records + + if at_first_page? + false + elsif paginate_backward? + @has_another_page + elsif paginate_forward? + true + end + end + + def cursor_for_next_page + if has_next_page? + data = order.cursor_attributes_for_node(records.last) + data[direction_key] = FORWARD_DIRECTION + cursor_converter.dump(data) + else + nil + end + end + + def cursor_for_previous_page + if has_previous_page? + data = order.cursor_attributes_for_node(records.first) + data[direction_key] = BACKWARD_DIRECTION + cursor_converter.dump(data) + end + end + + def cursor_for_first_page + cursor_converter.dump({ direction_key => FORWARD_DIRECTION }) + end + + def cursor_for_last_page + cursor_converter.dump({ direction_key => BACKWARD_DIRECTION }) + end + + delegate :each, :empty?, :any?, to: :records + + private + + attr_reader :keyset_scope, :order, :per_page, :cursor_converter, :direction_key, :cursor_attributes + + delegate :reversed_order, to: :order + + def at_last_page? + @at_last_page + end + + def at_first_page? + @at_first_page + end + + def per_page_plus_one + per_page + 1 + end + + def decode_cursor_attributes(cursor) + cursor.blank? ? {} : cursor_converter.parse(cursor) + end + + def set_pagination_helper_flags! + @direction = cursor_attributes.delete(direction_key.to_s) + + if cursor_attributes.blank? && @direction.blank? + @at_first_page = true + @direction = FORWARD_DIRECTION + elsif cursor_attributes.blank? + if paginate_forward? + @at_first_page = true + else + @at_last_page = true + end + end + end + + def paginate_backward? + @direction == BACKWARD_DIRECTION + end + + def paginate_forward? + @direction == FORWARD_DIRECTION + end + + def build_scope(scope) + keyset_aware_scope, success = Gitlab::Pagination::Keyset::SimpleOrderBuilder.build(scope) + + raise(UnsupportedScopeOrder, 'The order on the scope does not support keyset pagination') unless success + + keyset_aware_scope + end + end + end + end +end diff --git a/lib/gitlab/pagination/keyset/simple_order_builder.rb b/lib/gitlab/pagination/keyset/simple_order_builder.rb index 5ac5737c3be..76d6bbadaa4 100644 --- a/lib/gitlab/pagination/keyset/simple_order_builder.rb +++ b/lib/gitlab/pagination/keyset/simple_order_builder.rb @@ -26,6 +26,8 @@ module Gitlab def build order = if order_values.empty? primary_key_descending_order + elsif Gitlab::Pagination::Keyset::Order.keyset_aware?(scope) + Gitlab::Pagination::Keyset::Order.extract_keyset_order_object(scope) elsif ordered_by_primary_key? primary_key_order elsif ordered_by_other_column? |