Ruby on rails 4 升级到Rails 4时出错（未打开读取）

我尝试将一个应用程序从3.2升级到rails 4。我认为所有的gems冲突现在都已经解决了，尽管后来我知道可能会再次发生

当我尝试“捆绑exec rails s”并在浏览器中打开应用程序时，会出现以下错误：

IOError（未打开读取）

有人能帮忙吗？非常感谢你

以下是我使用的gem列表：

gem 'rails', '4.0.1'

gem 'sass-rails',   '~> 4.0.0'
gem 'coffee-rails', '~> 4.0.0'
gem 'uglifier', '>= 1.3.0'

gem 'jquery-rails'

gem 'jbuilder', '~> 1.2'
# add these gems to help with the transition:
gem 'protected_attributes'
gem 'rails-observers'
gem 'actionpack-page_caching'
gem 'actionpack-action_caching'
gem "activerecord-session_store"

以下是console的日志消息：

Started GET "/" for 127.0.0.1 at 2013-11-06 20:16:27 +1100
Processing by HomeController#index as HTML
  PCategory Load (0.5ms)  SELECT "p_categories".* FROM "p_categories"
  Rendered home/index.html.erb within layouts/application (4.1ms)
Completed 500 Internal Server Error in 15ms

IOError (not opened for reading):
  activesupport (4.0.1) lib/active_support/json/encoding.rb:256:in `each'
  activesupport (4.0.1) lib/active_support/json/encoding.rb:256:in `to_a'
  activesupport (4.0.1) lib/active_support/json/encoding.rb:256:in `as_json'
  activesupport (4.0.1) lib/active_support/json/encoding.rb:58:in `block in as_json'
  activesupport (4.0.1) lib/active_support/json/encoding.rb:81:in 'check_for_circular_references'
  activesupport (4.0.1) lib/active_support/json/encoding.rb:57:in `as_json'
  activesupport (4.0.1) lib/active_support/json/encoding.rb:296:in `block in as_json'
  activesupport (4.0.1) lib/active_support/json/encoding.rb:296:in `each'
  activesupport (4.0.1) lib/active_support/json/encoding.rb:296:in `map'
  activesupport (4.0.1) lib/active_support/json/encoding.rb:296:in `as_json'
  activesupport (4.0.1) lib/active_support/json/encoding.rb:58:in `block in as_json'
  activesupport (4.0.1) lib/active_support/json/encoding.rb:81:in g`check_for_circular_references'
  activesupport (4.0.1) lib/active_support/json/encoding.rb:57:in `as_json'
  activesupport (4.0.1) lib/active_support/json/encoding.rb:296:in `block in as_json'
  activesupport (4.0.1) lib/active_support/json/encoding.rb:296:in `each'
  activesupport (4.0.1) lib/active_support/json/encoding.rb:296:in `map'
  activesupport (4.0.1) lib/active_support/json/encoding.rb:296:in `as_json'
  activesupport (4.0.1) lib/active_support/json/encoding.rb:50:in `block in encode'
  activesupport (4.0.1) lib/active_support/json/encoding.rb:81:in `check_for_circular_references'
  activesupport (4.0.1) lib/active_support/json/encoding.rb:49:in `encode'
  activesupport (4.0.1) lib/active_support/json/encoding.rb:306:in `block in encode_json'
  activesupport (4.0.1) lib/active_support/json/encoding.rb:306:in `each'
  activesupport (4.0.1) lib/active_support/json/encoding.rb:306:in `map'

---

我最近也经历过这个问题。经过几天的反复试验，我最终注释了一组开发组gem（幸运猜测），然后逐个重新启用每个gem，用每个新启用的gem重建我的gem集。罪魁祸首原来是gem及其依赖项（它做了一些JSONP工作）

因此，我建议如下：

清空您的gem集（

rvm gemeset Empty

如果您使用的是rvm）

将Gemfile.lock文件重命名为Gemfile.lock.OLD（这可能不是必需的，但仅列出以防万一）

在您的Gemfile中，注释掉您怀疑处理请求或执行JSON工作的任何gem

运行

bundle install

以在没有注释掉gem的情况下重建gem集

重新启动服务器。如果仍然收到IOError，请重复步骤1-5。否则，继续执行步骤6

联合国评论你评论掉的宝石之一

运行

bundle install

安装gem及其依赖项

重新启动服务器。如果没有遇到IOR错误，请重复步骤6-8。否则，您上次启用的gem就是原因

---

事实证明，创业板冲突是我遇到的类似问题的罪魁祸首。我修复了一个使用Rails的间接相关问题中的代码问题。请看下面，我希望这对你有帮助

#fix for JSON gem/activesupport bug. More info: http://stackoverflow.com/questions/683989/how-do-you-deal-with-the-conflict-between-activesupportjson-and-the-json-gem
if defined?(ActiveSupport::JSON)
  [Object, Array, FalseClass, Float, Hash, Integer, NilClass, String, TrueClass].each do |klass|
    klass.class_eval do
      def to_json(*args)
        super(args)
      end
      def as_json(*args)
        super(args)
      end
    end
  end
end

---

我在ActiveModel序列化程序中体验到了这一点。我将ActiveModel序列化程序从0.8.1升级到了0.9，之后运行良好。

问题出在哪个gem上？恐怕这是很久以前的事了