题序迁移

db/migrate/20190605021834_migration_exercise_bank_question_number.rb

@@ -0,0 +1,22 @@
+class MigrationExerciseBankQuestionNumber < ActiveRecord::Migration
+  def up
+    Exercise.includes(:exercise_questions).find_each do |exercise|
+      if exercise.exercise_questions.pluck(:question_number).max != exercise.exercise_questions.size
+        exercise.exercise_questions.each_with_index do |question, j|
+          question.update_column('question_number', j + 1)
+        end
+      end
+    end
+
+    ExerciseBank.includes(:exercise_bank_questions).find_each do |exercise|
+      if exercise.exercise_bank_questions.pluck(:question_number).max != exercise.exercise_bank_questions.size
+        exercise.exercise_bank_questions.each_with_index do |question, j|
+          question.update_column('question_number', j + 1)
+        end
+      end
+    end
+  end
+
+  def down
+  end
+end