Ruby/Rails:访问实例变量数组中.each中的变量，导致Ruby解释器崩溃

Question

我写了一个mixin(基于我在博客上读到的东西)，似乎导致了一个问题

这是一个项目的链接:http://www.filehosting.org/file/details/263759/onlinescheduler.zip(或给我发电子邮件:[e-mail]，我会通过电子邮件发送)，我已经剥离了尽可能多的，因为它仍然会导致问题。要查看的关键文件有:

/lib/user_role.rb (near line 11)
/app/views/customers/index.html.erb (near line 16)
/app/controllers/customers_controller.rb (near line 47)

我将在这里布局重要的内容:

/lib/user_role.rb:

module UserRole
    def self.included(base)
      base.has_one :user, :as => :user_role, :autosave => true
      base.validate :user_must_be_valid
      base.alias_method_chain :user, :autobuild
      base.extend ClassMethods
      base.define_user_accessors
    end
    def user_with_autobuild
      user_without_autobuild || build_user
    end
    def method_missing(meth, *args, &blk)
      user.send(meth, *args, &blk)
    rescue NoMethodError
      super
    end
    module ClassMethods
      def define_user_accessors
        all_attributes = User.content_columns.map(&:name) + ["password", "password_confirmation"]
        ignored_attributes = ["created_at", "updated_at", "user_role_type"]
        attributes_to_delegate = all_attributes - ignored_attributes
        attributes_to_delegate.each do |attrib|
          class_eval <<-RUBY
            def #{attrib}
              user.#{attrib}
            end
            def #{attrib}=(value)
              self.user.#{attrib} = value
            end
            def #{attrib}?
              self.user.#{attrib}?
            end
          RUBY
        end
      end
    end
  protected
    def user_must_be_valid
      Logger.new(STDOUT).info('calling user_must_be_valid')
      unless user.valid?
        user.errors.each do |attr, message|
          errors.add(attr, message)
        end
      end
    end
  end

app/views/customers/index.html.erb:

...
<% @customers.each do |customer| %>
  <tr>
    <td><%= customer.account_id %></td>
...

访问customer会导致问题。我可以对@customers做任何事但是一旦我尝试访问customer....甚至@customers[0]....，我就会遇到问题。

生成

步骤

1)解压缩文件后，进入终端的根目录，执行以下命令:

bundle install
bundle exec rake db:drop
bundle exec rake db:migrate
rails s

2)打开浏览器到localhost:3000/customers，点击New Customer

3)按如下方式填写表格:

Account: 3
First Name: First
Last Name: Last
Email: [e-mail]
Password: 1234
Password confirmation: 1234

4)点击Create Customer按钮。

你应该重定向到localhost:3000/customers/1

当前行为

web服务器崩溃，因为你得到以下消息:

~/.rvm/rubies/ruby-1.9.2-p290/lib/libruby.so.1.9(+0x17b356) [0x7fef4a97e356]
~/.rvm/rubies/ruby-1.9.2-p290/lib/libruby.so.1.9(+0x1713ee) [0x7fef4a9743ee]
~/.rvm/rubies/ruby-1.9.2-p290/lib/libruby.so.1.9(+0x177243) [0x7fef4a97a243]
~/.rvm/rubies/ruby-1.9.2-p290/lib/libruby.so.1.9(rb_vm_invoke_proc+0x9f) [0x7fef4a97b08f]
~/.rvm/rubies/ruby-1.9.2-p290/lib/libruby.so.1.9(+0x17b644) [0x7fef4a97e644]
~/.rvm/rubies/ruby-1.9.2-p290/lib/libruby.so.1.9(+0x1713ee) [0x7fef4a9743ee]
~/.rvm/rubies/ruby-1.9.2-p290/lib/libruby.so.1.9(+0x177243) [0x7fef4a97a243]
~/.rvm/rubies/ruby-1.9.2-p290/lib/libruby.so.1.9(+0x1784f4) [0x7fef4a97b4f4]
~/.rvm/rubies/ruby-1.9.2-p290/lib/libruby.so.1.9(+0x178cb5) [0x7fef4a97bcb5]
~/.rvm/rubies/ruby-1.9.2-p290/lib/libruby.so.1.9(+0x17b50d) [0x7fef4a97e50d]
~/.rvm/rubies/ruby-1.9.2-p290/lib/libruby.so.1.9(+0x1713ee) [0x7fef4a9743ee]
[NOTE]
You may have encountered a bug in the Ruby interpreter or extension libraries.
Bug reports are welcome.
For details: http://www.ruby-lang.org/bugreport.html

重新运行web服务器并转到localhost:3000/customers有时会给你一个不同的错误。一个分段错误，它抱怨/lib/user_role.rb:11

Ruby 1.9.2-p290
Rails 3.0.9
RVM 1.8.1
Ubuntu 11.04

编辑

注意事项:如果你尝试在主机上运行相同的代码，它似乎没问题。例子:

(After entering rails c)
@customers = Customer.all
@customers.each do |customer|
  p customer.account_id
end
# this doesn't cause an error or crash.
@customer[0].first_name
=> "First"

Answer 1

如果删除:

def method_missing(meth, *args, &blk)
  customer.send(meth, *args, &blk)
rescue NoMethodError
  super
end

和

def method_missing(meth, *args, &blk)
  user.send(meth, *args, &blk)
rescue NoMethodError
  super
end

从lib目录中的x_role文件中取出

，它应该可以正常工作。另外，请查看控制器的继承资源和窗体的简单表单。