enable_module表被还原问题，原因课程新建失败时，@course对象未保存故其id为null，却做了删除操作级联删除enable_module表时sql语句就成了DELETE FROM `enabled_modules` WHERE `enabled_modules`.`course_id` IS NULL 而这刚好对应了所有项目数据。解决办法：去掉删除课程语句，未保存成功时不需删除

app/controllers/courses_controller.rb

@@ -269,7 +269,7 @@ class CoursesController < ApplicationController
           format.api { render :action => 'show', :status => :created, :location => url_for(:controller => 'courses', :action => 'show', :id => @course.id) }
         end
       else
-        @course.destroy
+        #@course.destroy
         respond_to do |format|
           format.html { render :action => 'new', :layout => 'base' } #Added by young
           format.api { render_validation_errors(@course) }