新课导语的回复错误

app/models/old_message_detail.rb

@@ -0,0 +1,2 @@
+class OldMessageDetail < ApplicationRecord
+end

db/migrate/20190823063747_modify_contents_for_old_message_details.rb

@@ -0,0 +1,13 @@
+class ModifyContentsForOldMessageDetails < ActiveRecord::Migration[5.2]
+  def change
+    messages = Message.where(subject: "新课导语").where.not(parent_id: 0).where("created_on < '2019-08-23 02:00:00'")
+    messages.find_each do |m|
+      m.update_column(:is_md, true)
+      message_detail = m.message_detail
+      if message_detail
+        content = OldMessageDetail.find_by(message_detail.id)&.content
+        message_detail.update_column(:content, content)
+      end
+    end
+  end
+end

spec/models/old_message_detail_spec.rb

@@ -0,0 +1,5 @@
+require 'rails_helper'
+
+RSpec.describe OldMessageDetail, type: :model do
+  pending "add some examples to (or delete) #{__FILE__}"
+end