dirty commit: can't get references to work correctly between any tables

app/models/dashboard/scale.rb

@@ -0,0 +1,44 @@
+module Dashboard
+  class Scale < ApplicationRecord
+    belongs_to :dashboard_measure
+    has_many :dashboard_survey_items
+    has_many :dashboard_survey_item_responses, through: :dashboard_survey_items
+    has_many :dashboard_admin_data_items
+
+    def score(school:, academic_year:)
+      @score ||= Hash.new do |memo, (school, academic_year)|
+        memo[[school, academic_year]] = begin
+          items = []
+          items << collect_survey_item_average(student_survey_items, school, academic_year)
+          items << collect_survey_item_average(teacher_survey_items, school, academic_year)
+
+          items.remove_blanks.average
+        end
+      end
+      @score[[school, academic_year]]
+    end
+
+    scope :teacher_scales, lambda {
+      where("scale_id LIKE 't-%'")
+    }
+    scope :student_scales, lambda {
+      where("scale_id LIKE 's-%'")
+    }
+
+    private
+
+    def collect_survey_item_average(survey_items, school, academic_year)
+      survey_items.map do |survey_item|
+        survey_item.score(school:, academic_year:)
+      end.remove_blanks.average
+    end
+
+    def teacher_survey_items
+      survey_items.teacher_survey_items
+    end
+
+    def student_survey_items
+      survey_items.student_survey_items
+    end
+  end
+end