diff options
Diffstat (limited to 'lib/gitlab/graphql/pagination/keyset/last_items.rb')
| -rw-r--r-- | lib/gitlab/graphql/pagination/keyset/last_items.rb | 57 |
1 files changed, 57 insertions, 0 deletions
diff --git a/lib/gitlab/graphql/pagination/keyset/last_items.rb b/lib/gitlab/graphql/pagination/keyset/last_items.rb new file mode 100644 index 00000000000..45bf15236c1 --- /dev/null +++ b/lib/gitlab/graphql/pagination/keyset/last_items.rb @@ -0,0 +1,57 @@ +# frozen_string_literal: true + +module Gitlab + module Graphql + module Pagination + module Keyset + # This class handles the last(N) ActiveRecord call even if a special ORDER BY configuration is present. + # For the last(N) call, ActiveRecord calls reverse_order, however for some cases it raises + # ActiveRecord::IrreversibleOrderError error. + class LastItems + # rubocop: disable CodeReuse/ActiveRecord + def self.take_items(scope, count) + if custom_order = lookup_custom_reverse_order(scope.order_values) + items = scope.reorder(*custom_order).first(count) # returns a single record when count is nil + items.is_a?(Array) ? items.reverse : items + else + scope.last(count) + end + end + # rubocop: enable CodeReuse/ActiveRecord + + # Detect special ordering and provide the reversed order + def self.lookup_custom_reverse_order(order_values) + if ordering_by_merged_at_and_mr_id_desc?(order_values) + [ + Gitlab::Database.nulls_first_order('merge_request_metrics.merged_at', 'ASC'), # reversing the order + MergeRequest.arel_table[:id].asc + ] + elsif ordering_by_merged_at_and_mr_id_asc?(order_values) + [ + Gitlab::Database.nulls_first_order('merge_request_metrics.merged_at', 'DESC'), + MergeRequest.arel_table[:id].asc + ] + end + end + + def self.ordering_by_merged_at_and_mr_id_desc?(order_values) + order_values.size == 2 && + order_values.first.to_s == Gitlab::Database.nulls_last_order('merge_request_metrics.merged_at', 'DESC') && + order_values.last.is_a?(Arel::Nodes::Descending) && + order_values.last.to_sql == MergeRequest.arel_table[:id].desc.to_sql + end + + def self.ordering_by_merged_at_and_mr_id_asc?(order_values) + order_values.size == 2 && + order_values.first.to_s == Gitlab::Database.nulls_last_order('merge_request_metrics.merged_at', 'ASC') && + order_values.last.is_a?(Arel::Nodes::Descending) && + order_values.last.to_sql == MergeRequest.arel_table[:id].desc.to_sql + end + + private_class_method :ordering_by_merged_at_and_mr_id_desc? + private_class_method :ordering_by_merged_at_and_mr_id_asc? + end + end + end + end +end |