NoMethodError：未定義的方法`格格」的零：NilClass

Question

日誌

/gems/pdfkit-0.6.2/lib/pdfkit/configuration.rb:22 in "wkhtmltopdf" 
/gems/pdfkit-0.6.2/lib/pdfkit/pdfkit.rb:32 in "initialize" 
/gems/pdfkit-0.6.2/lib/pdfkit/middleware.rb:22 in "new" 
/gems/pdfkit-0.6.2/lib/pdfkit/middleware.rb:22 in "call" 
/gems/warden-1.2.3/lib/warden/manager.rb:35 in "block in call" 
/gems/warden-1.2.3/lib/warden/manager.rb:34 in "catch" 
/gems/warden-1.2.3/lib/warden/manager.rb:34 in "call" 
/gems/actionpack-3.2.17/lib/action_dispatch/middleware/best_standards_support.rb:17 in "call" 
/gems/rack-1.4.5/lib/rack/etag.rb:23 in "call" 
/gems/rack-1.4.5/lib/rack/conditionalget.rb:25 in "call" 
/gems/actionpack-3.2.17/lib/action_dispatch/middleware/head.rb:14 in "call" 
/gems/actionpack-3.2.17/lib/action_dispatch/middleware/params_parser.rb:21 in "call" 
/gems/actionpack-3.2.17/lib/action_dispatch/middleware/flash.rb:242 in "call" 
/gems/rack-1.4.5/lib/rack/session/abstract/id.rb:210 in "context" 
/gems/rack-1.4.5/lib/rack/session/abstract/id.rb:205 in "call" 

我得到的異常處理此錯誤（減速板）。無法知道這個錯誤來自哪裏，因此無法修復。

可能是這個錯誤來自pdfkit，但是當我在我的本地測試時，它工作正常，也在服務器上工作正常，但我每天都會收到此錯誤。

Answer 1

關於Ruby的奇妙之處在於它是在源代碼中分發的。這是很容易跟蹤line 22 of configuration.rb：

@wkhtmltopdf ||= (defined?(Bundler::GemfileError) && File.exists?('Gemfile') ? `bundle exec which wkhtmltopdf` : `which wkhtmltopdf`).chomp 

所以，which wkhtmltopdf回報nil。你需要確保它沒有。考慮安裝wkhtmltopdf，無論如何。寶石中的說明明確指出這是所需的安裝步驟：https://github.com/pdfkit/pdfkit