我在heroku上有一个使用mongoid和delayed_job的应用程序，我已经将ruby版本从1.9.2更改为1.9.3我收到错误
undefined method `match' for nil:NilClass
当我尝试将对象保存到mongoid数据库时，我的mongoid.yaml文件看起来像
production:
sessions:
default:
uri: <%= ENV['MONGOHQ_URL'] %>
options:
skip_version_check: true
safe: true
跟踪就在这里
NoMethodError: undefined method `match' for nil:NilClass
from /app/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.13/lib/mongoid/sessions/mongo_uri.rb:49:in `initialize'
from /app/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.13/lib/mongoid/sessions/factory.rb:103:in `new'
from /app/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.13/lib/mongoid/sessions/factory.rb:103:in `parse'
from /app/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.13/lib/mongoid/sessions/factory.rb:62:in `create_session'
from /app/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.13/lib/mongoid/sessions/factory.rb:43:in `default'
from /app/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.13/lib/mongoid/sessions.rb:109:in `default'
from /app/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.13/lib/mongoid/sessions.rb:378:in `__session__'
from /app/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.13/lib/mongoid/sessions.rb:213:in `mongo_session'
from /app/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.13/lib/mongoid/sessions.rb:157:in `collection'
from /app/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.13/lib/mongoid/sessions.rb:25:in `collection'
from /app/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.13/lib/mongoid/persistence/operations.rb:27:in `collection'
from /app/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.13/lib/mongoid/persistence/operations/insert.rb:27:in `block in persist'
from /app/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.13/lib/mongoid/persistence/insertion.rb:25:in `block (2 levels) in prepare'
from /app/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.6/lib/active_support/callbacks.rb:403:in `_run__4034630009416245289__create__685777988298500290__callbacks'
from /app/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.6/lib/active_support/callbacks.rb:405:in `__run_callback'
from /app/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.6/lib/active_support/callbacks.rb:385:in `_run_create_callbacks'
... 2 levels...
from /app/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.13/lib/mongoid/persistence/insertion.rb:24:in `block in prepare'
from /app/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.6/lib/active_support/callbacks.rb:403:in `_run__4034630009416245289__save__685777988298500290__callbacks'
from /app/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.6/lib/active_support/callbacks.rb:405:in `__run_callback'
from /app/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.6/lib/active_support/callbacks.rb:385:in `_run_save_callbacks'
from /app/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.6/lib/active_support/callbacks.rb:81:in `run_callbacks'
from /app/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.13/lib/mongoid/callbacks.rb:114:in `run_callbacks'
from /app/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.13/lib/mongoid/persistence/insertion.rb:23:in `prepare'
from /app/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.13/lib/mongoid/persistence/operations/insert.rb:26:in `persist'
from /app/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.13/lib/mongoid/persistence.rb:50:in `insert'
from /app/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.13/lib/mongoid/persistence.rb:79:in `save'
from (irb):2
from /app/vendor/bundle/ruby/1.9.1/gems/railties-3.2.6/lib/rails/commands/console.rb:47:in `start'
from /app/vendor/bundle/ruby/1.9.1/gems/railties-3.2.6/lib/rails/commands/console.rb:8:in `start'
from /app/vendor/bundle/ruby/1.9.1/gems/railties-3.2.6/lib/rails/commands.rb:41:in `<top (required)>'
from script/rails:6:in `require'
任何人都可以帮助我吗？提前谢谢
答案 0 :(得分：1)
发生错误是因为此方法https://github.com/mongoid/mongoid/blob/v3.0.13/lib/mongoid/sessions/mongo_uri.rb#L49的输入参数为nil。
进一步查看调用堆栈以找出此字符串的来源（请参阅https://github.com/mongoid/mongoid/blob/v3.0.13/lib/mongoid/sessions/factory.rb#L103），看起来您的uri配置参数为零。 uri密钥存在但为空，因此您可以通过运行MONGOHQ_URL来检查heroku config配置参数。这应该由MongoHQ插件设置。
堆栈跟踪中的Ruby 1.9.1路径无需担心。见Why Do Heroku Stack Traces indicate Ruby 1.9.1 is in use?