Fix N+1 query on signup bucket/requested_bucket in UserConProfileDrop

app/liquid_drops/user_con_profile_drop.rb

@@ -51,6 +51,7 @@ class UserConProfileDrop < Liquid::Drop
 
   # @api
   def initialize(user_con_profile)
+    super()
     @user_con_profile = user_con_profile
   end
 
@@ -65,7 +66,17 @@ def signups
     user_con_profile
       .signups
       .where.not(state: "withdrawn")
-      .includes(event: :event_category, run: { rooms: nil, event: { team_members: :user_con_profile } })
+      .includes(
+        :bucket,
+        :requested_bucket,
+        event: :event_category,
+        run: {
+          rooms: nil,
+          event: {
+            team_members: :user_con_profile
+          }
+        }
+      )
       .to_a
   end
 

test/liquid_drops/user_con_profile_drop_test.rb

@@ -63,5 +63,30 @@
       signups = user_con_profile_drop.signups
       withdrawn_signups.each { |signup| assert_not_includes signups, signup }
     end
+
+    it "does not issue a bucket query per signup" do
+      queries =
+        count_queries(/registration_policy_buckets/) do
+          user_con_profile_drop.signups.each do |signup|
+            signup.bucket
+            signup.requested_bucket
+          end
+        end
+      assert_operator queries, :<=, 2, "expected a constant number of bucket queries regardless of signup count"
+    end
+  end
+
+  private
+
+  def count_queries(pattern)
+    count = 0
+    subscriber =
+      ActiveSupport::Notifications.subscribe("sql.active_record") do |*, payload|
+        count += 1 if pattern.match?(payload[:sql])
+      end
+    yield
+    count
+  ensure
+    ActiveSupport::Notifications.unsubscribe(subscriber) if subscriber
   end
 end