Refactor CycleAnalytics base stage class and model

app/models/cycle_analytics.rb

@@ -31,7 +31,7 @@ class CycleAnalytics
   end
 
   def [](stage_name)
-    Gitlab::CycleAnalytics::Stage[stage_name].new(project: @project, options: @options)
+    Gitlab::CycleAnalytics::Stage[stage_name].new(projects: [@project], options: @options)
   end
 
   private

app/serializers/analytics_stage_entity.rb

@@ -6,7 +6,13 @@ class AnalyticsStageEntity < Grape::Entity
   expose :legend
   expose :description
 
-  expose :median, as: :value do |stage|
-    stage.median && !stage.median.zero? ? distance_of_time_in_words(stage.median) : nil
+  expose :medians, as: :values do |stage|
+    medians = stage.medians
+
+    unless medians.blank?
+      medians.each do |id, median|
+        medians[id] = distance_of_time_in_words(median)
+      end
+    end
   end
 end

lib/gitlab/cycle_analytics/base_query.rb

@@ -14,7 +14,7 @@ module Gitlab
       def stage_query
         query = mr_closing_issues_table.join(issue_table).on(issue_table[:id].eq(mr_closing_issues_table[:issue_id]))
           .join(issue_metrics_table).on(issue_table[:id].eq(issue_metrics_table[:issue_id]))
-          .where(issue_table[:project_id].in(project_ids)) # rubocop:disable Gitlab/ModuleWithInstanceVariables
+          .where(issue_table[:project_id].in(Arel.sql(@projects.select(:id).to_sql))) # rubocop:disable Gitlab/ModuleWithInstanceVariables
           .where(issue_table[:created_at].gteq(@options[:from])) # rubocop:disable Gitlab/ModuleWithInstanceVariables
 
         # Load merge_requests
@@ -26,10 +26,6 @@ module Gitlab
 
         query
       end
-
-      def project_ids
-        @projects.map(&:id)
-      end
     end
   end
 end