为什么我不能得到rake db：迁移到ruby.railstutorial.org工作
我决定通过这个教程。 在我创建一个新的应用程序并添加新user:string email:string然后在app目录中执行rake db:migrate之后，我得到了这个输出：
rake aborted! undefined method `task' for # /usr/local/rvm/gems/ruby-1.9.2-p180@rails3tutorial/gems/railties-3.0.7/lib/rails/application.rb:215:in `initialize_tasks' /usr/local/rvm/gems/ruby-1.9.2-p180@rails3tutorial/gems/railties-3.0.7/lib/rails/application.rb:139:in `load_tasks' /usr/local/rvm/gems/ruby-1.9.2-p180@rails3tutorial/gems/railties-3.0.7/lib/rails/application.rb:77:in `method_missing' /Users/zigloo99/rails_projects/demo_app/Rakefile:7:in `' /usr/local/rvm/gems/ruby-1.9.2-p180@global/gems/rake-0.9.0/lib/rake/rake_module.rb:25:in `load' /usr/local/rvm/gems/ruby-1.9.2-p180@global/gems/rake-0.9.0/lib/rake/rake_module.rb:25:in `load_rakefile' /usr/local/rvm/gems/ruby-1.9.2-p180@global/gems/rake-0.9.0/lib/rake/application.rb:495:in `raw_load_rakefile' /usr/local/rvm/gems/ruby-1.9.2-p180@global/gems/rake-0.9.0/lib/rake/application.rb:78:in `block in load_rakefile' /usr/local/rvm/gems/ruby-1.9.2-p180@global/gems/rake-0.9.0/lib/rake/application.rb:129:in `standard_exception_handling' /usr/local/rvm/gems/ruby-1.9.2-p180@global/gems/rake-0.9.0/lib/rake/application.rb:77:in `load_rakefile' /usr/local/rvm/gems/ruby-1.9.2-p180@global/gems/rake-0.9.0/lib/rake/application.rb:61:in `block in run' /usr/local/rvm/gems/ruby-1.9.2-p180@global/gems/rake-0.9.0/lib/rake/application.rb:129:in `standard_exception_handling' /usr/local/rvm/gems/ruby-1.9.2-p180@global/gems/rake-0.9.0/lib/rake/application.rb:59:in `run' /usr/local/rvm/gems/ruby-1.9.2-p180@global/gems/rake-0.9.0/bin/rake:31:in `' /usr/local/rvm/gems/ruby-1.9.2-p180@global/bin/rake:19:in `load' /usr/local/rvm/gems/ruby-1.9.2-p180@global/bin/rake:19:in `'
我正在使用RVM太ruby 1.9.2和rails 3.0.7，如教程中所示。 有什么想法吗？
另一种解决方案是在启动新的rails项目之前在Gemfile中要求rake 0.8.7。
# Gemfile gem 'rake', '0.8.7', :require => 'rake'
然后运行bundle install
这是因为最新版本的Rake（0.9.0）在Rails 3.0应用程序上被打破，我们目前正在等待一个可靠的修复。
现在，解决此错误的方法是在应用程序的Rakefile的Rakefile行上方添加此行：
::Application.send :include, ::Rake::DSL if defined?(::Rake::DSL)