Clear stats cache after adding/removing PB votes

app/models/budget/ballot/line.rb

@@ -16,6 +16,8 @@ class Line < ApplicationRecord
       scope :by_investment, ->(investment_id) { where(investment_id: investment_id) }
 
       before_validation :set_denormalized_ids
+      after_create :clear_stats_cache
+      after_destroy :clear_stats_cache
 
       def check_enough_resources
         ballot.lock!
@@ -43,6 +45,10 @@ def set_denormalized_ids
           self.group_id   ||= investment&.group_id
           self.budget_id  ||= investment&.budget_id
         end
+
+        def clear_stats_cache
+          Budget::Stats.new(budget).clear_cache
+        end
     end
   end
 end

app/models/budget/stats.rb

@@ -92,6 +92,14 @@ def headings
     groups
   end
 
+  def clear_cache
+    cache_keys = Rails.cache.instance_variable_get("@data")&.keys || []
+    budget_cache_keys = cache_keys.select { |cache_key| cache_key.starts_with?("budgets_stats/#{budget.id}/") }
+    budget_cache_keys.each do |key|
+      Rails.cache.delete(key)
+    end
+  end
+
   private
 
     def phase_methods

spec/system/admin/stats_spec.rb

@@ -147,6 +147,26 @@
         expect(page).to have_content "VOTES\n3"
         expect(page).to have_content "PARTICIPANTS\n2"
       end
+
+      scenario "Clear cache after new votes", :with_cache do
+        create(:user, ballot_lines: [investment])
+
+        visit admin_stats_path
+        click_link "Participatory Budgets"
+        within("#budget_#{budget.id}") do
+          click_link "Final voting"
+        end
+
+        expect(page).to have_content "VOTES\n1"
+        expect(page).to have_content "PARTICIPANTS\n1"
+
+        create(:user, ballot_lines: [investment])
+
+        refresh
+
+        expect(page).to have_content "VOTES\n2"
+        expect(page).to have_content "PARTICIPANTS\n2"
+      end
     end
   end