CanCan：參數的錯誤數目（1代表0）

Question

我似乎無法獲得CanCan的工作。事實證明，這很令人沮喪，尤其是當我遵循規則手冊，似乎嘗試了所有在陽光下操作的技巧。

我使用的是Rails 3.1.2，Devise 2.1.2和CanCan 1.6.8。我按照RyanB here的描述設置了一個單獨的角色模型。

這是我的代碼。

1）ability.rb

class Ability 
    include CanCan::Ability 

    def initializer(user) 
    user ||= User.new # For users with no account 

    if (user.has_role?(:admin)) || (user.has_role?(:mod)) 
     can :manage, :all 

    elsif user.has_role?(:registered) 
     can :read, :all 
     can :create, :all 

     can :update, Question do |question| 
     question.try(:user) == (user || user.has_role?(:admin) || user.has_role?(:mod)) 
     end 

     can :destroy, Question do |question| 
     question.try(:user) == (user || user.has_role?(:admin) || user.has_role?(:mod)) 
     end 

    else 
     can :read, :all   
    end 
    end 
end 

2）has_role？前過濾器

before_filter :authenticate_user!, :except => :show 

load_and_authorize_resource 
skip_authorize_resource :only => :show 

授權與對所有的動作相同的錯誤慚慚結果的任何控制器在user.rb定義

def has_role?(role_sym) 
    roles.any? { |r| r.name.underscore.to_sym == role_sym } 
end 

3）控制器。

編輯：堆棧跟蹤

cancan (1.6.8) lib/cancan/controller_additions.rb:352:in `initialize' 
cancan (1.6.8) lib/cancan/controller_additions.rb:352:in `new' 
cancan (1.6.8) lib/cancan/controller_additions.rb:352:in `current_ability' 
cancan (1.6.8) lib/cancan/controller_resource.rb:207:in `current_ability' 
cancan (1.6.8) lib/cancan/controller_resource.rb:77:in `load_collection?' 
cancan (1.6.8) lib/cancan/controller_resource.rb:33:in `load_resource' 
cancan (1.6.8) lib/cancan/controller_resource.rb:25:in `load_and_authorize_resource' 
cancan (1.6.8) lib/cancan/controller_resource.rb:10:in `block in add_before_filter' 
activesupport (3.2.1) lib/active_support/callbacks.rb:429:in `_run__458654864__process_action__156152648__callbacks' 
activesupport (3.2.1) lib/active_support/callbacks.rb:405:in `__run_callback' 
activesupport (3.2.1) lib/active_support/callbacks.rb:385:in `_run_process_action_callbacks' 
activesupport (3.2.1) lib/active_support/callbacks.rb:81:in `run_callbacks' 
actionpack (3.2.1) lib/abstract_controller/callbacks.rb:17:in `process_action' 
actionpack (3.2.1) lib/action_controller/metal/rescue.rb:29:in `process_action' 
actionpack (3.2.1) lib/action_controller/metal/instrumentation.rb:30:in `block in process_action' 
activesupport (3.2.1) lib/active_support/notifications.rb:123:in `block in instrument' 
activesupport (3.2.1) lib/active_support/notifications/instrumenter.rb:20:in `instrument' 
activesupport (3.2.1) lib/active_support/notifications.rb:123:in `instrument' 
actionpack (3.2.1) lib/action_controller/metal/instrumentation.rb:29:in `process_action' 
actionpack (3.2.1) lib/action_controller/metal/params_wrapper.rb:205:in `process_action' 
activerecord (3.2.1) lib/active_record/railties/controller_runtime.rb:18:in `process_action' 
actionpack (3.2.1) lib/abstract_controller/base.rb:121:in `process' 
actionpack (3.2.1) lib/abstract_controller/rendering.rb:45:in `process' 
actionpack (3.2.1) lib/action_controller/metal.rb:203:in `dispatch' 
actionpack (3.2.1) lib/action_controller/metal/rack_delegation.rb:14:in `dispatch' 
actionpack (3.2.1) lib/action_controller/metal.rb:246:in `block in action' 
actionpack (3.2.1) lib/action_dispatch/routing/route_set.rb:66:in `call' 
actionpack (3.2.1) lib/action_dispatch/routing/route_set.rb:66:in `dispatch' 
actionpack (3.2.1) lib/action_dispatch/routing/route_set.rb:30:in `call' 
journey (1.0.4) lib/journey/router.rb:68:in `block in call' 
journey (1.0.4) lib/journey/router.rb:56:in `each' 
journey (1.0.4) lib/journey/router.rb:56:in `call' 
actionpack (3.2.1) lib/action_dispatch/routing/route_set.rb:589:in `call' 
warden (1.2.1) lib/warden/manager.rb:35:in `block in call' 
warden (1.2.1) lib/warden/manager.rb:34:in `catch' 
warden (1.2.1) lib/warden/manager.rb:34:in `call' 
actionpack (3.2.1) lib/action_dispatch/middleware/best_standards_support.rb:17:in `call' 
rack (1.4.1) lib/rack/etag.rb:23:in `call' 
rack (1.4.1) lib/rack/conditionalget.rb:25:in `call' 
actionpack (3.2.1) lib/action_dispatch/middleware/head.rb:14:in `call' 
actionpack (3.2.1) lib/action_dispatch/middleware/params_parser.rb:21:in `call' 
actionpack (3.2.1) lib/action_dispatch/middleware/flash.rb:242:in `call' 
rack (1.4.1) lib/rack/session/abstract/id.rb:205:in `context' 
rack (1.4.1) lib/rack/session/abstract/id.rb:200:in `call' 
actionpack (3.2.1) lib/action_dispatch/middleware/cookies.rb:338:in `call' 
activerecord (3.2.1) lib/active_record/query_cache.rb:64:in `call' 
activerecord (3.2.1) lib/active_record/connection_adapters/abstract/connection_pool.rb:443:in `call' 
actionpack (3.2.1) lib/action_dispatch/middleware/callbacks.rb:28:in `block in call' 
activesupport (3.2.1) lib/active_support/callbacks.rb:405:in `_run__446710069__call__461654473__callbacks' 
activesupport (3.2.1) lib/active_support/callbacks.rb:405:in `__run_callback' 
activesupport (3.2.1) lib/active_support/callbacks.rb:385:in `_run_call_callbacks' 
activesupport (3.2.1) lib/active_support/callbacks.rb:81:in `run_callbacks' 
actionpack (3.2.1) lib/action_dispatch/middleware/callbacks.rb:27:in `call' 
actionpack (3.2.1) lib/action_dispatch/middleware/reloader.rb:65:in `call' 
actionpack (3.2.1) lib/action_dispatch/middleware/remote_ip.rb:31:in `call' 
actionpack (3.2.1) lib/action_dispatch/middleware/debug_exceptions.rb:16:in `call' 
actionpack (3.2.1) lib/action_dispatch/middleware/show_exceptions.rb:56:in `call' 
railties (3.2.1) lib/rails/rack/logger.rb:26:in `call_app' 
railties (3.2.1) lib/rails/rack/logger.rb:16:in `call' 
actionpack (3.2.1) lib/action_dispatch/middleware/request_id.rb:22:in `call' 
rack (1.4.1) lib/rack/methodoverride.rb:21:in `call' 
rack (1.4.1) lib/rack/runtime.rb:17:in `call' 
activesupport (3.2.1) lib/active_support/cache/strategy/local_cache.rb:72:in `call' 
rack (1.4.1) lib/rack/lock.rb:15:in `call' 
actionpack (3.2.1) lib/action_dispatch/middleware/static.rb:53:in `call' 
railties (3.2.1) lib/rails/engine.rb:479:in `call' 
railties (3.2.1) lib/rails/application.rb:220:in `call' 
rack (1.4.1) lib/rack/content_length.rb:14:in `call' 
railties (3.2.1) lib/rails/rack/log_tailer.rb:14:in `call' 
rack (1.4.1) lib/rack/handler/webrick.rb:59:in `service' 
/home/administrator/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/webrick/httpserver.rb:138:in `service' 
/home/administrator/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/webrick/httpserver.rb:94:in `run' 
/home/administrator/.rvm/rubies/ruby-1 

.9.3-p125/lib/ruby/1.9.1/webrick/server.rb:191:in `block in start_thread' 

Answer 1

好，看來，我沒有跟着規則書的所有規則。雖然我看不出這可能是一個問題。爲了得到這個工作，我刪除了我手動創建的文件ability.rb文件，並使用rails g cancan:ability命令在同一目錄中生成相同的文件，並使用相同的代碼。現在它像一個魅力。