NoMethodError - 정의되지 않은 메소드 'id'for nil : NilClass :

Question

부모/자식 관계가있는 테이블에 숫자가 있습니다. 'parent_id'라는 열이 있는데, 부모 열의 'id'열과 일치시키는 데 사용하고 있습니다. 문제는 내가 NoMethodError 얻고있다 - 정의되지 않은 메서드`ID를 '전무을 위해 : NilClass : 직접 확인하려고 할 때'그것은 두 번째 줄에 잡힐

number = Number.find_by_twilio_sid(params[:sid]) 
forward = Number.find_by_parent_id(number.id) 
erb "#{forward.name}" 

PARENT_ID '

app.rb 내가 찾은 번호에서 이드에게 전화하면.

NoMethodError - undefined method `id' for nil:NilClass: 
/Users/chadsakonchick/Projects/cloud-phone/lib/voice.rb:52:in `block in <top (required)>' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:1603:in `call' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:1603:in `block in compile!' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:966:in `[]' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:966:in `block (3 levels) in route!' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:985:in `route_eval' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:966:in `block (2 levels) in route!' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:1006:in `block in process_route' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:1004:in `catch' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:1004:in `process_route' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:964:in `block in route!' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:963:in `each' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:963:in `route!' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:1076:in `block in dispatch!' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:1058:in `block in invoke' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:1058:in `catch' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:1058:in `invoke' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:1073:in `dispatch!' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:898:in `block in call!' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:1058:in `block in invoke' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:1058:in `catch' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:1058:in `invoke' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:898:in `call!' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:886:in `call' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/rack-protection-1.5.3/lib/rack/protection/xss_header.rb:18:in `call' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/rack-protection-1.5.3/lib/rack/protection/base.rb:49:in `call' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/rack-protection-1.5.3/lib/rack/protection/base.rb:49:in `call' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/rack-protection-1.5.3/lib/rack/protection/path_traversal.rb:16:in `call' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/rack-protection-1.5.3/lib/rack/protection/json_csrf.rb:18:in `call' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/rack-protection-1.5.3/lib/rack/protection/base.rb:49:in `call' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/rack-protection-1.5.3/lib/rack/protection/base.rb:49:in `call' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/rack-protection-1.5.3/lib/rack/protection/frame_options.rb:31:in `call' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/rack-1.6.0.beta/lib/rack/session/abstract/id.rb:225:in `context' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/rack-1.6.0.beta/lib/rack/session/abstract/id.rb:220:in `call' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/rack-1.6.0.beta/lib/rack/logger.rb:15:in `call' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/rack-1.6.0.beta/lib/rack/commonlogger.rb:33:in `call' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:217:in `call' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:210:in `call' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/rack-1.6.0.beta/lib/rack/head.rb:13:in `call' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/rack-1.6.0.beta/lib/rack/methodoverride.rb:22:in `call' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/show_exceptions.rb:21:in `call' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:180:in `call' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:2014:in `call' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:1478:in `block in call' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:1788:in `synchronize' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:1478:in `call' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/rack-1.6.0.beta/lib/rack/handler/webrick.rb:89:in `service' 
/Users/chadsakonchick/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/webrick/httpserver.rb:138:in `service' 
/Users/chadsakonchick/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/webrick/httpserver.rb:94:in `run' 
/Users/chadsakonchick/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/webrick/server.rb:295:in `block in start_thread' 
[2014-11-12 22:44:14] ERROR NoMethodError: undefined method `join' for #<String:0x007fd013edcc28> 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/show_exceptions.rb:37:in `rescue in call' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/show_exceptions.rb:21:in `call' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:180:in `call' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:2014:in `call' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:1478:in `block in call' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:1788:in `synchronize' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/sinatra-1.4.5/lib/sinatra/base.rb:1478:in `call' 
/Users/chadsakonchick/.rvm/gems/ruby-2.1.2/gems/rack-1.6.0.beta/lib/rack/handler/webrick.rb:89:in `service' 
/Users/chadsakonchick/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/webrick/httpserver.rb:138:in `service' 
/Users/chadsakonchick/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/webrick/httpserver.rb:94:in `run' 
/Users/chadsakonchick/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/webrick/server.rb:295:in `block in start_thread' 
localhost - - [12/Nov/2014:22:44:14 CST] "GET /forward/A9R0cadcba83424fdead5602dzQbb83e61 HTTP/1.1" 500 347 
- -> /forward/A9R0cadcba83424fdead5602dzQbb83e61 

Answer 1

이 지정한 twilio_sid하면 Number 테이블에 항목이 없음을 의미 다음은 터미널 반응이다.

하나는 :

number = Number.find_by_twilio_sid(params[:sid]) 
forward_name = Number.find_by_parent_id(number.try(:id)).try(:name) 
erb "#{forward_name}"