Railscasts＃241 NoMethodError未定義方法`[]'爲零：NilClass

SessionsController＃create中有一個NoMethodError。 Twitter認證頁面出現，但回調URL不起作用。在twitter認證後，該頁面不會呈現給網站。以下是不同文件中的代碼。Railscasts＃241 NoMethodError未定義方法`[]'爲零：NilClass

在routes.rb中

Blog::Application.routes.draw do 
    root :to => "posts#index" 

    match "/auth/:provider/callback" => "sessions#create" 
    match "/signout" => "sessions#destroy", :as => :signout 

    resources :posts 
end

在sessions_controller.rb

class SessionsController < ApplicationController 
    def create 
    auth = request.env["omniauth.auth"] 
    user = User.find_by_provider_and_uid(auth["provider"], auth["uid"]) || User.create_with_omniauth(auth) 
    session[:user_id] = user.id 
    redirect_to root_url, :notice => "Signed in!" 
    end 

    def destroy 
    session[:user_id] = nil 
    redirect_to root_url, :notice => "Signed out!" 
    end 
end

在user.rb

class User < ActiveRecord::Base 
    def self.create_with_omniauth(auth) 
    create! do |user| 
     user.provider = auth["provider"] 
     user.uid = auth["uid"] 
     user.name = auth["user_info"]["name"] 
    end 
    end 
end

完全跟蹤：

app/models/user.rb:6:in `block in create_with_omniauth' 
activerecord (3.2.0) lib/active_record/validations.rb:40:in `create!' 
app/models/user.rb:3:in `create_with_omniauth' 
app/controllers/sessions_controller.rb:4:in `create' 
actionpack (3.2.0) lib/action_controller/metal/implicit_render.rb:4:in `send_action' 
actionpack (3.2.0) lib/abstract_controller/base.rb:167:in `process_action' 
actionpack (3.2.0) lib/action_controller/metal/rendering.rb:10:in `process_action' 
actionpack (3.2.0) lib/abstract_controller/callbacks.rb:18:in `block in process_action' 
activesupport (3.2.0) lib/active_support/callbacks.rb:414:in `_run__168269495__process_action__8122527__callbacks' 
activesupport (3.2.0) lib/active_support/callbacks.rb:405:in `__run_callback' 
activesupport (3.2.0) lib/active_support/callbacks.rb:385:in `_run_process_action_callbacks' 
activesupport (3.2.0) lib/active_support/callbacks.rb:81:in `run_callbacks' 
actionpack (3.2.0) lib/abstract_controller/callbacks.rb:17:in `process_action' 
actionpack (3.2.0) lib/action_controller/metal/rescue.rb:29:in `process_action' 
actionpack (3.2.0) lib/action_controller/metal/instrumentation.rb:30:in `block in process_action' 
activesupport (3.2.0) lib/active_support/notifications.rb:123:in `block in instrument' 
activesupport (3.2.0) lib/active_support/notifications/instrumenter.rb:20:in `instrument' 
activesupport (3.2.0) lib/active_support/notifications.rb:123:in `instrument' 
actionpack (3.2.0) lib/action_controller/metal/instrumentation.rb:29:in `process_action' 
actionpack (3.2.0) lib/action_controller/metal/params_wrapper.rb:205:in `process_action' 
activerecord (3.2.0) lib/active_record/railties/controller_runtime.rb:18:in `process_action' 
actionpack (3.2.0) lib/abstract_controller/base.rb:121:in `process' 
actionpack (3.2.0) lib/abstract_controller/rendering.rb:45:in `process' 
actionpack (3.2.0) lib/action_controller/metal.rb:203:in `dispatch' 
actionpack (3.2.0) lib/action_controller/metal/rack_delegation.rb:14:in `dispatch' 
actionpack (3.2.0) lib/action_controller/metal.rb:246:in `block in action' 
actionpack (3.2.0) lib/action_dispatch/routing/route_set.rb:66:in `call' 
actionpack (3.2.0) lib/action_dispatch/routing/route_set.rb:66:in `dispatch' 
actionpack (3.2.0) 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 (3.2.0) lib/action_dispatch/routing/route_set.rb:570:in `call' 
omniauth (1.1.4) lib/omniauth/strategy.rb:401:in `call_app!' 
omniauth (1.1.4) lib/omniauth/strategy.rb:363:in `callback_phase' 
omniauth-oauth (1.0.1) lib/omniauth/strategies/oauth.rb:58:in `callback_phase' 
omniauth (1.1.4) lib/omniauth/strategy.rb:226:in `callback_call' 
omniauth (1.1.4) lib/omniauth/strategy.rb:182:in `call!' 
omniauth (1.1.4) lib/omniauth/strategy.rb:164:in `call' 
omniauth (1.1.4) lib/omniauth/builder.rb:49:in `call' 
actionpack (3.2.0) lib/action_dispatch/middleware/best_standards_support.rb:17:in `call' 
rack (1.4.5) lib/rack/etag.rb:23:in `call' 
rack (1.4.5) lib/rack/conditionalget.rb:25:in `call' 
actionpack (3.2.0) lib/action_dispatch/middleware/head.rb:14:in `call' 
actionpack (3.2.0) lib/action_dispatch/middleware/params_parser.rb:21:in `call' 
actionpack (3.2.0) lib/action_dispatch/middleware/flash.rb:242:in `call' 
rack (1.4.5) lib/rack/session/abstract/id.rb:210:in `context' 
rack (1.4.5) lib/rack/session/abstract/id.rb:205:in `call' 
actionpack (3.2.0) lib/action_dispatch/middleware/cookies.rb:338:in `call' 
activerecord (3.2.0) lib/active_record/query_cache.rb:64:in `call' 
activerecord (3.2.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:443:in `call' 
actionpack (3.2.0) lib/action_dispatch/middleware/callbacks.rb:28:in `block in call' 
activesupport (3.2.0) lib/active_support/callbacks.rb:405:in `_run__208198798__call__80088063__callbacks' 
activesupport (3.2.0) lib/active_support/callbacks.rb:405:in `__run_callback' 
activesupport (3.2.0) lib/active_support/callbacks.rb:385:in `_run_call_callbacks' 
activesupport (3.2.0) lib/active_support/callbacks.rb:81:in `run_callbacks' 
actionpack (3.2.0) lib/action_dispatch/middleware/callbacks.rb:27:in `call' 
actionpack (3.2.0) lib/action_dispatch/middleware/reloader.rb:65:in `call' 
actionpack (3.2.0) lib/action_dispatch/middleware/remote_ip.rb:31:in `call' 
actionpack (3.2.0) lib/action_dispatch/middleware/debug_exceptions.rb:16:in `call' 
actionpack (3.2.0) lib/action_dispatch/middleware/show_exceptions.rb:56:in `call' 
railties (3.2.0) lib/rails/rack/logger.rb:26:in `call_app' 
railties (3.2.0) lib/rails/rack/logger.rb:16:in `call' 
actionpack (3.2.0) lib/action_dispatch/middleware/request_id.rb:22:in `call' 
rack (1.4.5) lib/rack/methodoverride.rb:21:in `call' 
rack (1.4.5) lib/rack/runtime.rb:17:in `call' 
activesupport (3.2.0) lib/active_support/cache/strategy/local_cache.rb:72:in `call' 
rack (1.4.5) lib/rack/lock.rb:15:in `call' 
actionpack (3.2.0) lib/action_dispatch/middleware/static.rb:53:in `call' 
railties (3.2.0) lib/rails/engine.rb:479:in `call' 
railties (3.2.0) lib/rails/application.rb:220:in `call' 
rack (1.4.5) lib/rack/content_length.rb:14:in `call' 
railties (3.2.0) lib/rails/rack/log_tailer.rb:14:in `call' 
rack (1.4.5) lib/rack/handler/webrick.rb:59:in `service' 
/home/sakshi/.rvm/rubies/ruby-2.0.0-p195/lib/ruby/2.0.0/webrick/httpserver.rb:138:in `service' 
/home/sakshi/.rvm/rubies/ruby-2.0.0-p195/lib/ruby/2.0.0/webrick/httpserver.rb:94:in `run' 
/home/sakshi/.rvm/rubies/ruby-2.0.0-p195/lib/ruby/2.0.0/webrick/server.rb:295:in `block in start_thread'

控制檯：

NoMethodError (undefined method `[]' for nil:NilClass): 
    app/models/user.rb:6:in `block in create_with_omniauth' 
    app/models/user.rb:3:in `create_with_omniauth' 
    app/controllers/sessions_controller.rb:4:in `create'

來源

2014-01-10 Sakshi Jain

請提供堆棧跟蹤 –

請務必使用帶有您的應用程序正在運行的IP地址和端口的應用程序url –

如果您遇到此錯誤，？ –

做出改變這一行：

user.name = auth["info"]["name"]

和它的作品。

來源

2014-01-11 13:37:41

在app/models/user.rb 6行：

user.name = auth["user_info"]["name"]

的auth散列不具有針對「USER_INFO」鍵的值，所以它返回nil;那麼你試圖在nil上調用[]方法，這會引發異常。

嘗試在塊加入p auth驗證auth哈希內容：

class User < ActiveRecord::Base 
    def self.create_with_omniauth(auth) 
    create! do |user| 
     puts "DEBUG " + "=" * 50 
     p auth 
     user.provider = auth["provider"] 
     user.uid = auth["uid"] 
     user.name = auth["user_info"]["name"] 
    end 
    end 
end

來源

2014-01-10 15:35:40

我已經更新了答案，您應該能夠在日誌中看到它 –

我遇到了同樣的錯誤。 –

是的，它應該是，但是'auth'哈希的內容是什麼？ –

Railscasts＃241 NoMethodError未定義方法`[]'爲零：NilClass

回答

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