Rails 变量第一次加载，然后为零！

Question

我收到以下错误：

ActionView::TemplateError (You have a nil object when you didn't expect it!
You might have expected an instance of Array.
The error occurred while evaluating nil.include?) on line #24 of app/views/index/index.html.erb:
21: <% @achievements.each do |achievement| %>
22:     <%= achievement.name %>
23:     <%= achievement.level %>
24:     by <%= achievement.user.username %><br/>
25: <% end %>

奇怪的是，第一次加载索引页时没有任何问题。当我刷新时，我收到上面的错误。

控制器看起来像这样：

class IndexController < ApplicationController
    def index
        @achievements = Achievement.find(:all)
    end
end

与缓存有关吗？或者它使用了太多内存？如果是这样，我可以用其他方式加载用户名吗？我很困惑！

Answer 1

尝试通过在查找中添加“:include => :user”来急切加载用户：

class IndexController < ApplicationController
    def index
        @achievements = Achievement.find(:all, :include => :user)
    end
end