57 lines
2.4 KiB
Ruby
57 lines
2.4 KiB
Ruby
# frozen_string_literal: true
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module Gitlab
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module Graphql
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module Pagination
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module Keyset
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# This class handles the last(N) ActiveRecord call even if a special ORDER BY configuration is present.
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# For the last(N) call, ActiveRecord calls reverse_order, however for some cases it raises
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# ActiveRecord::IrreversibleOrderError error.
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class LastItems
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# rubocop: disable CodeReuse/ActiveRecord
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def self.take_items(scope, count)
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if custom_order = lookup_custom_reverse_order(scope.order_values)
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items = scope.reorder(*custom_order).first(count) # returns a single record when count is nil
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items.is_a?(Array) ? items.reverse : items
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else
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scope.last(count)
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end
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end
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# rubocop: enable CodeReuse/ActiveRecord
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# Detect special ordering and provide the reversed order
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def self.lookup_custom_reverse_order(order_values)
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if ordering_by_merged_at_and_mr_id_desc?(order_values)
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[
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Gitlab::Database.nulls_first_order('merge_request_metrics.merged_at', 'ASC'), # reversing the order
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MergeRequest.arel_table[:id].asc
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]
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elsif ordering_by_merged_at_and_mr_id_asc?(order_values)
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[
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Gitlab::Database.nulls_first_order('merge_request_metrics.merged_at', 'DESC'),
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MergeRequest.arel_table[:id].asc
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]
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end
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end
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def self.ordering_by_merged_at_and_mr_id_desc?(order_values)
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order_values.size == 2 &&
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order_values.first.to_s == Gitlab::Database.nulls_last_order('merge_request_metrics.merged_at', 'DESC') &&
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order_values.last.is_a?(Arel::Nodes::Descending) &&
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order_values.last.to_sql == MergeRequest.arel_table[:id].desc.to_sql
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end
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def self.ordering_by_merged_at_and_mr_id_asc?(order_values)
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order_values.size == 2 &&
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order_values.first.to_s == Gitlab::Database.nulls_last_order('merge_request_metrics.merged_at', 'ASC') &&
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order_values.last.is_a?(Arel::Nodes::Descending) &&
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order_values.last.to_sql == MergeRequest.arel_table[:id].desc.to_sql
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end
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private_class_method :ordering_by_merged_at_and_mr_id_desc?
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private_class_method :ordering_by_merged_at_and_mr_id_asc?
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end
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end
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end
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end
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end
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