fix

app/decorators/tiding_decorator.rb

@@ -30,6 +30,7 @@ module TidingDecorator
   end
 
   def strip_html(text, len = 0, suffix = "...")
+    text = text.to_s
     str = ""
     if !text.nil? && text.length > 0
       str = text.gsub(/<\/?.*?>/, '').strip

app/models/apply_add_school.rb

@@ -9,6 +9,7 @@ class ApplyAddSchool < ApplicationRecord
   private
 
   def send_notify
-    tidings.create!(user_id: 1, status: 0, trigger_user_id: user_id, belong_container: school, tiding_type: 'Apply')
+    Tiding.create!(user_id: 1, status: 0, container_id: id, container_type: 'ApplyAddSchools',
+                   trigger_user_id: user_id, belong_container: school, tiding_type: 'Apply')
   end
 end

db/migrate/20190802105008_tranfer_tiding_data.rb

@@ -0,0 +1,5 @@
+class TranferTidingData < ActiveRecord::Migration[5.2]
+  def change
+    Tiding.where(container_type: 'ApplyAddSchool').update_all(container_type: 'ApplyAddSchools')
+  end
+end