修复讨论区at错误

app/controllers/boards_controller.rb

@@ -80,8 +80,10 @@ class BoardsController < ApplicationController
         end
       end
 
-      @project.boards.messages.each do |m|
-        User.current.at_messages.unviewed('Message', m.id).each {|x| x.viewed!}
+      @project.boards.each do |board|
+        board.messages.each do |m|
+          User.current.at_messages.unviewed('Message', m.id).each {|x| x.viewed!}
+        end
       end
 
     elsif @course