解决冲突

app/models/hack_code.rb

@@ -1,3 +1,4 @@
 class HackCode < ApplicationRecord
   # 编程题代码相关
+  belongs_to :hack
 end

db/migrate/20200223021427_sync_subjectds_mobile.rb

@@ -1,7 +1,7 @@
 class SyncSubjectdsMobile < ActiveRecord::Migration[5.2]
   def change
     SubDisciplineContainer.where(container_type: "Subject").find_each do |sc|
-      Subject.find(sc.container_id).update_column('show_mobile', true)
+      Subject.find(sc.container_id).update_column("show_mobile", true)
     end
   end
 end