迁移公式

db/migrate/20191226092304_modify_task_pass_2_for_challenges.rb

@@ -0,0 +1,8 @@
+class ModifyTaskPass2ForChallenges < ActiveRecord::Migration[5.2]
+  def change
+    challenges = Challenge.where("task_pass like '%frac%'")
+    challenges.find_each do |c|
+      c.update_column(:task_pass, c.task_pass.gsub('\f\frac', '\frac'))
+    end
+  end
+end