NoMethodError：nil的未定义方法“chomp”：NilClass [关闭]答案

【问题标题】：NoMethodError: undefined method `chomp' for nil:NilClass [closed]NoMethodError：nil的未定义方法“chomp”：NilClass [关闭]
【发布时间】：2014-10-02 02:17:32
【问题描述】：

日志

/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"

我在异常（Airbrake）中收到此错误。无法知道此错误来自何处，因此无法修复。

可能是这个错误来自 pdfkit，但是当我在本地测试时它工作正常，并且在服务器上工作正常但每天我都会收到这个错误。

【问题讨论】：

标签： ruby-on-rails ruby-on-rails-3 pdfkit

【解决方案1】：

Ruby 的美妙之处在于它以源代码形式分发。很容易找到line 22 of configuration.rb：

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

所以，which wkhtmltopdf 返回nil。你需要确保它没有。考虑安装wkhtmltopdf，不管它是什么。 gem 中的说明明确指出这是必需的安装步骤：https://github.com/pdfkit/pdfkit

【讨论】：