修复当课程ID不存在时加入课程按钮报404而不会给出提示的BUG

app/controllers/courses_controller.rb

@@ -21,7 +21,7 @@ class CoursesController < ApplicationController
   before_filter :toggleCourse, only: [:finishcourse, :restartcourse]
 
   before_filter :require_login, :only => [:join, :unjoin]
-  before_filter :allow_join, :only => [:join]
+  #before_filter :allow_join, :only => [:join]
 
   def join
     if User.current.logged?
@@ -29,7 +29,7 @@ class CoursesController < ApplicationController
       if course
         @state = 4
       else
-        unless User.current.member_of_course? course
+        unless (allow_join && User.current.member_of_course?(course))
           if params[:course_password] == course.password
             members = []
             members << Member.new(:role_ids => [10], :user_id => User.current.id)