先对课程下的班级归档，再删除该课程，此时就不能再恢复班级了

app/controllers/syllabuses_controller.rb

@@ -57,6 +57,13 @@ class SyllabusesController < ApplicationController
   end
 
   def delete_syllabus
+    if @syllabus.courses.empty?
+      @status = 1
+    elsif @syllabus.courses.not_deleted.empty?
+      @status = 2
+    else
+      @status = 3
+    end
     respond_to do |format|
       format.js
     end

app/views/syllabuses/_delete_syllabus.html.erb

@@ -6,15 +6,17 @@
   </div>
 
   <div style='text-align:center;font-family: "微软雅黑","宋体"' class="mt20 f14">
-    <% if @syllabus.courses.not_deleted.empty? %>
+    <% if @status == 1 %>
       确认删除该课程吗？
+    <% elsif @status == 2 %>
+      该课程下存在归档班级，不能删除。
     <% else %>
       该课程下已经存在班级，不能删除。
     <% end %>
   </div>
 
   <div style='width:164px; margin:0 auto; margin-top: 15px; text-align:center; font-family: "微软雅黑","宋体"'>
-    <% if @syllabus.courses.not_deleted.empty? %>
+    <% if @status == 1 %>
         <a href='javascript:void(0);' class='sy_btn_grey fl mr5' style="margin-left: 25px;" onclick='hideModal()'>取消</a>
         <%=link_to '确认', syllabus_path(@syllabus), :class => 'sy_btn_blue fl', :method => 'delete'%>
     <% else %>