perf: reduce number of queries by requesting grouped_responses once instead of for each measure

app/models/measure.rb

@@ -163,21 +163,13 @@ class Measure < ActiveRecord::Base
   def collect_survey_item_average(survey_items:, school:, academic_year:)
     @collect_survey_item_average ||= Hash.new do |memo, (survey_items, school, academic_year)|
       averages = survey_items.map do |survey_item|
-        grouped_responses(school:, academic_year:)[survey_item.id]
+        SurveyItemResponse.grouped_responses(school:, academic_year:)[survey_item.id]
       end.remove_blanks
       memo[[survey_items, school, academic_year]] = averages.average || 0
     end
     @collect_survey_item_average[[survey_items, school, academic_year]]
   end
 
-  def grouped_responses(school:, academic_year:)
-    @grouped_responses ||= Hash.new do |memo, (school, academic_year)|
-      memo[[school, academic_year]] =
-        SurveyItemResponse.where(school:, academic_year:).group(:survey_item_id).average(:likert_score)
-    end
-    @grouped_responses[[school, academic_year]]
-  end
-
   def sufficient_student_data?(school:, academic_year:)
     return false unless includes_student_survey_items?
 
@@ -227,7 +219,8 @@ class Measure < ActiveRecord::Base
 
   def admin_data_averages(school:, academic_year:)
     @admin_data_averages ||= Hash.new do |memo, (school, academic_year)|
-      memo[[school, academic_year]] = AdminDataValue.where(school:, academic_year:, admin_data_item: admin_data_items).pluck(:likert_score)
+      memo[[school, academic_year]] =
+        AdminDataValue.where(school:, academic_year:, admin_data_item: admin_data_items).pluck(:likert_score)
     end
     @admin_data_averages[[school, academic_year]]
   end

app/models/survey_item_response.rb

@@ -16,7 +16,7 @@ class SurveyItemResponse < ActiveRecord::Base
   has_one :measure, through: :survey_item
 
   scope :exclude_boston, lambda {
-    includes(school: :district).where.not("district.name": "Boston")
+                           includes(school: :district).where.not("district.name": "Boston")
                          }
 
   scope :averages_for_grade, lambda { |survey_items, school, academic_year, grade|
@@ -49,4 +49,12 @@ class SurveyItemResponse < ActiveRecord::Base
       school:, academic_year:, grade: school.grades(academic_year:)
     ).where("student_races.race_id": race.id).group(:survey_item_id).having("count(*) >= 10").average(:likert_score)
   }
+
+  def self.grouped_responses(school:, academic_year:)
+    @grouped_responses ||= Hash.new do |memo, (school, academic_year)|
+      memo[[school, academic_year]] =
+        SurveyItemResponse.where(school:, academic_year:).group(:survey_item_id).average(:likert_score)
+    end
+    @grouped_responses[[school, academic_year]]
+  end
 end