如何判断是哪个 gem 导致 Rails 无法启动？

Question

我在尝试启动我的 Rails 2.3.8 项目时遇到此错误：

nil:NilClass (NoMethodError) 的未定义方法 `map'

我以前卖过一堆 gem，这是一个草率的项目，在 environment.rb 中没有相应的 config.gem 行。

我怎样才能恢复这个项目以便它可以启动？我在供应商中拥有所有这些宝石。我想过只是删除它们，启动项目，然后等待失败重新添加最新版本的 gems。这可行吗？

堆栈跟踪没有帮助：

/opt/ruby-enterprise-1.8.7-2010.02/lib/ruby/site_ruby/1.8/rubygems.rb:223:in `activate': undefined method `map' for nil:NilClass (NoMethodError)
from /opt/ruby-enterprise-1.8.7-2010.02/lib/ruby/site_ruby/1.8/rubygems.rb:249:in `activate'
from /opt/ruby-enterprise-1.8.7-2010.02/lib/ruby/site_ruby/1.8/rubygems.rb:248:in `each'
from /opt/ruby-enterprise-1.8.7-2010.02/lib/ruby/site_ruby/1.8/rubygems.rb:248:in `activate'
from /opt/ruby-enterprise-1.8.7-2010.02/lib/ruby/site_ruby/1.8/rubygems.rb:249:in `activate'
from /opt/ruby-enterprise-1.8.7-2010.02/lib/ruby/site_ruby/1.8/rubygems.rb:248:in `each'
from /opt/ruby-enterprise-1.8.7-2010.02/lib/ruby/site_ruby/1.8/rubygems.rb:248:in `activate'
from /opt/ruby-enterprise-1.8.7-2010.02/lib/ruby/site_ruby/1.8/rubygems.rb:1082:in `gem'
from ./script/../config/../vendor/rails/railties/lib/rails/gem_dependency.rb:73:in `add_load_paths'
from ./script/../config/../vendor/rails/railties/lib/initializer.rb:301:in `add_gem_load_paths'
from ./script/../config/../vendor/rails/railties/lib/initializer.rb:301:in `each'
from ./script/../config/../vendor/rails/railties/lib/initializer.rb:301:in `add_gem_load_paths'
from ./script/../config/../vendor/rails/railties/lib/initializer.rb:132:in `process'
from ./script/../config/../vendor/rails/railties/lib/initializer.rb:113:in `send'
from ./script/../config/../vendor/rails/railties/lib/initializer.rb:113:in `run'
from /Library/Illumaware/code/evokat25/config/environment.rb:19
from /opt/ruby-enterprise-1.8.7-2010.02/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require'
from /opt/ruby-enterprise-1.8.7-2010.02/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:in `require'
from /Library/Illumaware/code/evokat25/vendor/rails/activesupport/lib/active_support/dependencies.rb:156:in `require'
from /Library/Illumaware/code/evokat25/vendor/rails/activesupport/lib/active_support/dependencies.rb:521:in `new_constants_in'
from /Library/Illumaware/code/evokat25/vendor/rails/activesupport/lib/active_support/dependencies.rb:156:in `require'
from /Library/Illumaware/code/evokat25/vendor/rails/railties/lib/commands/server.rb:84
from /opt/ruby-enterprise-1.8.7-2010.02/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require'
from /opt/ruby-enterprise-1.8.7-2010.02/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:in `require'
from script/server:3

Answer 1

完整的堆栈跟踪应包含引发此异常的源文件和行号。

Stacktrace 可以在命令提示符中，当您启动 rails 项目时，或者在网页上。

Answer 2

我通过对 environment.rb 文件中的 config.gem 行的试错编辑找到了罪魁祸首。