Question

我在部署的Rails 2.3.5应用程序中遇到以下错误：

NoMethodError（未定义方法“to_sym”对于nil:NilClass）：

我的本地测试应用程序安装使用的是Sqlite，没有出现错误，但是我的部署应用程序运行Mysql时出现了错误。两者之间唯一的区别是我的本地机器上运行Ruby 1.8.7，而部署服务器上运行1.8.6。

I ve 包括以下代码:User.rb和错误标识。我是继申报性授权和假装授权铁路预报之后设立的。

编辑：这是application_controller的代码，我在其中使用before_filter设置current_user：

class ApplicationController < ActionController::Base
  helper :all
  helper_method :current_user_session, :current_user 
  before_filter :set_current_user

  protected 

  def set_current_user
    Authorization.current_user = current_user
  end

  def current_user_session  
    return @current_user_session if defined?(@current_user_session)  
    @current_user_session = UserSession.find  
  end  

  def current_user  
    @current_user = current_user_session && current_user_session.record  
  end
end

把这个翻译成中文：--

用户b:

class User < ActiveRecord::Base
  acts_as_authentic 

  has_many :products
  has_many :transactions

  ROLES = %w[admin dmstaff staff faculty]

  def role_symbols
    [role.to_sym]
  end  

end

错误日志：

NoMethodError（未定义方法“to_sym”对于nil:NilClass）：
  app/models/user.rb:10:in `role_symbols 
  /usr/lib/ruby/gems/1.8/gems/declarative_authorization 0.4/lib/declarative_authorization/authorization.rb:242:in `roles_for 
  /usr/lib/ruby/gems/1.8/gems/declarative_authorization-0.4/lib/declarative_authorization/authorization.rb:296:in  `user_roles_privleges_from_options 
  /usr/lib/ruby/gems/1.8/gems/declarative_authorization-0.4/lib/declarative_authorization/authorization.rb:161:in `permit! 
  /usr/lib/ruby/gems/1.8/gems/declarative_authorization-0.4/lib/declarative_authorization/in_controller.rb:580:in `permit! 
  /usr/lib/ruby/gems/1.8/gems/declarative_authorization-0.4/lib/declarative_authorization/in_controller.rb:109:in `filter_access_filter 
  /usr/lib/ruby/gems/1.8/gems/declarative_authorization-0.4/lib/declarative_authorization/in_controller.rb:109:in `each 
  /usr/lib/ruby/gems/1.8/gems/declarative_authorization-0.4/lib/declarative_authorization/in_controller.rb:109:in `all? 
  /usr/lib/ruby/gems/1.8/gems/declarative_authorization-0.4/lib/declarative_authorization/in_controller.rb:109:in `filter_access_filter 
  passenger (2.2.5) lib/phusion_passenger/rack/request_handler.rb:95:in `process_request 
  passenger (2.2.5) lib/phusion_passenger/abstract_request_handler.rb:207:in `main_loop 
  passenger (2.2.5) lib/phusion_passenger/railz/application_spawner.rb:378:in `start_request_handler 
  passenger (2.2.5) lib/phusion_passenger/railz/application_spawner.rb:336:in `handle_spawn_application 
  passenger (2.2.5) lib/phusion_passenger/utils.rb:183:in `safe_fork 
  passenger (2.2.5) lib/phusion_passenger/railz/application_spawner.rb:334:in `handle_spawn_application 
  passenger (2.2.5) lib/phusion_passenger/abstract_server.rb:352:in `__send__ 
  passenger (2.2.5) lib/phusion_passenger/abstract_server.rb:352:in `main_loop 
  passenger (2.2.5) lib/phusion_passenger/abstract_server.rb:196:in `start_synchronously 
  passenger (2.2.5) lib/phusion_passenger/abstract_server.rb:163:in `start 
  passenger (2.2.5) lib/phusion_passenger/railz/application_spawner.rb:213:in `start 
  passenger (2.2.5) lib/phusion_passenger/spawn_manager.rb:262:in `spawn_rails_application 
  passenger (2.2.5) lib/phusion_passenger/abstract_server_collection.rb:126:in `lookup_or_add 
  passenger (2.2.5) lib/phusion_passenger/spawn_manager.rb:256:in `spawn_rails_application 
  passenger (2.2.5) lib/phusion_passenger/abstract_server_collection.rb:80:in `synchronize 
  passenger (2.2.5) lib/phusion_passenger/abstract_server_collection.rb:79:in `synchronize 
  passenger (2.2.5) lib/phusion_passenger/spawn_manager.rb:255:in `spawn_rails_application 
  passenger (2.2.5) lib/phusion_passenger/spawn_manager.rb:154:in `spawn_application 
  passenger (2.2.5) lib/phusion_passenger/spawn_manager.rb:287:in `handle_spawn_application 
  passenger (2.2.5) lib/phusion_passenger/abstract_server.rb:352:in `__send__ 
  passenger (2.2.5) lib/phusion_passenger/abstract_server.rb:352:in `main_loop 
  passenger (2.2.5) lib/phusion_passenger/abstract_server.rb:196:in `start_synchronously 

Rendering /var/data/app/current/public/500.html (500 Internal Server Error)

Answer 1

  def role_symbols
    [role.to_sym]
  end

role 是 Nil。你有定义 role 吗？

Answer 2

在某个时刻，你的代码期望一个类型为User的对象，但现在却是nil。你是否有做过类似的事情？

@user = User.find_by_login("Mary")
@user.role_symbols

在哪裡，“Mary”是不存在的用戶登錄？發布任何您調用role_symbols方法的地方，我們可以提供更多幫助。

编辑：看一下这个方法#roles_for（链接），没有深入研究这个插件，我想说的是，在您的代码执行这一点上，#current_user没有设置。

Answer 3

表格上没有设置角色属性。您必须使用救援代码，并检查为什么会发生这种情况。

在调用 role.to_sym 之前，测试 role 值是否已设置。

友情链接