70 lines
2.5 KiB
Ruby
70 lines
2.5 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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class QueryBuilder
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def initialize(arel_table, order_list, decoded_cursor, before_or_after)
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@arel_table, @order_list, @decoded_cursor, @before_or_after = arel_table, order_list, decoded_cursor, before_or_after
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if order_list.empty?
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raise ArgumentError.new('No ordering scopes have been supplied')
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end
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end
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# Based on whether the main field we're ordering on is NULL in the
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# cursor, we can more easily target our query condition.
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# We assume that the last ordering field is unique, meaning
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# it will not contain NULLs.
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# We currently only support two ordering fields.
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#
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# Example of the conditions for
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# relation: Issue.order(relative_position: :asc).order(id: :asc)
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# after cursor: relative_position: 1500, id: 500
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#
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# when cursor[relative_position] is not NULL
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#
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# ("issues"."relative_position" > 1500)
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# OR (
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# "issues"."relative_position" = 1500
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# AND
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# "issues"."id" > 500
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# )
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# OR ("issues"."relative_position" IS NULL)
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#
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# when cursor[relative_position] is NULL
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#
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# "issues"."relative_position" IS NULL
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# AND
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# "issues"."id" > 500
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#
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def conditions
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attr_values = order_list.map do |field|
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name = field.try(:attribute_name) || field
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decoded_cursor[name]
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end
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if order_list.count == 1 && attr_values.first.nil?
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raise Gitlab::Graphql::Errors::ArgumentError.new('Before/after cursor invalid: `nil` was provided as only sortable value')
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end
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if order_list.count == 1 || attr_values.first.present?
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Keyset::Conditions::NotNullCondition.new(arel_table, order_list, attr_values, operators, before_or_after).build
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else
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Keyset::Conditions::NullCondition.new(arel_table, order_list, attr_values, operators, before_or_after).build
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end
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end
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private
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attr_reader :arel_table, :order_list, :decoded_cursor, :before_or_after
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def operators
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order_list.map { |field| field.operator_for(before_or_after) }
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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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end
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