Fix problem with sorting in GraphQL by case expression

ee/app/models/ee/vulnerability.rb

@@ -103,8 +103,8 @@ module EE
       scope :order_title_desc, -> { reorder(title: :desc, id: :desc) }
       scope :order_created_at_asc, -> { reorder(created_at: :asc, id: :desc) }
       scope :order_created_at_desc, -> { reorder(created_at: :desc, id: :desc) }
-      scope :order_report_type_asc, -> { reorder(report_type_order.asc, id: :desc) }
-      scope :order_report_type_desc, -> { reorder(report_type_order.desc, id: :desc) }
+      scope :order_report_type_asc, -> { select(*arel.projections, report_type_order.as('case_order_value')).reorder(report_type_order.asc, id: :desc) }
+      scope :order_report_type_desc, -> { select(*arel.projections, report_type_order.as('case_order_value')).reorder(report_type_order.desc, id: :desc) }
       scope :order_id_desc, -> { reorder(id: :desc) }
 
       scope :with_limit, -> (maximum) { limit(maximum) }

lib/gitlab/graphql/pagination/keyset/order_info.rb

@@ -95,7 +95,7 @@ module Gitlab
             elsif ordering_by_similarity?(order_value)
               ['similarity', order_value.direction, order_value.expr]
             elsif ordering_by_case?(order_value)
-              [order_value.expr.case.name.to_s, order_value.direction, order_value.expr]
+              ['case_order_value', order_value.direction, order_value.expr]
             else
               [order_value.expr.name, order_value.direction, nil]
             end

spec/lib/gitlab/graphql/pagination/keyset/order_info_spec.rb

@@ -69,7 +69,7 @@ RSpec.describe Gitlab::Graphql::Pagination::Keyset::OrderInfo do
 
       it 'assigns the right attribute name, named function, and direction' do
         expect(order_list.count).to eq 1
-        expect(order_list.first.attribute_name).to eq 'pending_delete'
+        expect(order_list.first.attribute_name).to eq 'case_order_value'
         expect(order_list.first.named_function).to be_kind_of(Arel::Nodes::Case)
         expect(order_list.first.sort_direction).to eq :asc
       end