我正在尝试在 Heroku 上获取我的应用程序，但是当我运行 heroku rake db:migrate 时，出现以下错误。似乎 event_calendar gem 导致了问题，但问题是，我已经卸载了它。在 gemfile 或 gemfile.lock 中没有对它的引用，它也没有出现在 gem 列表中。尝试 gem list -d event_calendar 只返回* LOCAL GEMS *，据我所知，与 event_calendar 关联的所有文件都已删除。为什么 Heroku 似乎仍然有问题？
rake aborted!
undefined method `id' for class `EventCalendar::Event'
/app/.bundle/gems/ruby/1.9.1/gems/event_calendar-0.0.2/lib/event_calendar/event.
rb:7:in `undef_method'
/app/.bundle/gems/ruby/1.9.1/gems/event_calendar-0.0.2/lib/event_calendar/event.
rb:7:in `<class:Event>'
/app/.bundle/gems/ruby/1.9.1/gems/event_calendar-0.0.2/lib/event_calendar/event.
rb:5:in `<class:EventCalendar>'
/app/.bundle/gems/ruby/1.9.1/gems/event_calendar-0.0.2/lib/event_calendar/event.
rb:1:in `<top (required)>'
/app/.bundle/gems/ruby/1.9.1/gems/activesupport-3.0.9/lib/active_support/depende
ncies.rb:239:in `require'
/app/.bundle/gems/ruby/1.9.1/gems/activesupport-3.0.9/lib/active_support/depende
ncies.rb:239:in `block in require'
/app/.bundle/gems/ruby/1.9.1/gems/activesupport-3.0.9/lib/active_support/depende
ncies.rb:225:in `block in load_dependency'
/app/.bundle/gems/ruby/1.9.1/gems/activesupport-3.0.9/lib/active_support/depende
ncies.rb:596:in `new_constants_in'
/app/.bundle/gems/ruby/1.9.1/gems/activesupport-3.0.9/lib/active_support/depende
ncies.rb:225:in `load_dependency'
/app/.bundle/gems/ruby/1.9.1/gems/activesupport-3.0.9/lib/active_support/depende
ncies.rb:239:in `require'
/app/.bundle/gems/ruby/1.9.1/gems/event_calendar-0.0.2/lib/event_calendar.rb:4:i
n `<top (required)>'
/usr/ruby1.9.2/lib/ruby/gems/1.9.1/gems/bundler-1.0.7/lib/bundler/runtime.rb:64:
in `require'
/usr/ruby1.9.2/lib/ruby/gems/1.9.1/gems/bundler-1.0.7/lib/bundler/runtime.rb:64:
in `block (2 levels) in require'
/usr/ruby1.9.2/lib/ruby/gems/1.9.1/gems/bundler-1.0.7/lib/bundler/runtime.rb:62:
in `each'
/usr/ruby1.9.2/lib/ruby/gems/1.9.1/gems/bundler-1.0.7/lib/bundler/runtime.rb:62:
in `block in require'
/usr/ruby1.9.2/lib/ruby/gems/1.9.1/gems/bundler-1.0.7/lib/bundler/runtime.rb:51:
in `each'
/usr/ruby1.9.2/lib/ruby/gems/1.9.1/gems/bundler-1.0.7/lib/bundler/runtime.rb:51:
in `require'
/usr/ruby1.9.2/lib/ruby/gems/1.9.1/gems/bundler-1.0.7/lib/bundler.rb:112:in `require'
/app/config/application.rb:7:in `<top (required)>'
<internal:lib/rubygems/custom_require>:29:in `require'
<internal:lib/rubygems/custom_require>:29:in `require'
/app/Rakefile:4:in `<top (required)>'
/usr/ruby1.9.2/lib/ruby/1.9.1/rake.rb:2373:in `load'
/usr/ruby1.9.2/lib/ruby/1.9.1/rake.rb:2373:in `raw_load_rakefile'
/usr/ruby1.9.2/lib/ruby/1.9.1/rake.rb:2007:in `block in load_rakefile'
/usr/ruby1.9.2/lib/ruby/1.9.1/rake.rb:2058:in `standard_exception_handling'
/usr/ruby1.9.2/lib/ruby/1.9.1/rake.rb:2006:in `load_rakefile'
/usr/ruby1.9.2/lib/ruby/1.9.1/rake.rb:1991:in `run'
/usr/ruby1.9.2/bin/rake:31:in `<main>'