我正在关注railstutorial.org上的 rails 教程
我在第 2 章中,并尝试按照说明使用 rake 迁移数据库:“要继续演示应用程序,我们首先需要使用 Rake 迁移数据库(框 2.1)”:
$ rake db:migrate
这不起作用,我收到以下错误:
C:\Users\USER1\rails_project\demo_app>rake db:migrate
(in C:/Users/USER1/rails_project/demo_app)
rake aborted!
uninitialized constant Rake::DSL
C:/Ruby192/lib/ruby/1.9.1/rake.rb:2482:in `const_missing'
C:/Ruby192/lib/ruby/gems/1.9.1/gems/rake-0.9.0/lib/rake/tasklib.rb:8:in `<class:TaskLib>'
C:/Ruby192/lib/ruby/gems/1.9.1/gems/rake-0.9.0/lib/rake/tasklib.rb:6:in `<module:Rake>'
C:/Ruby192/lib/ruby/gems/1.9.1/gems/rake-0.9.0/lib/rake/tasklib.rb:3:in `<top (required)>'
C:/Ruby192/lib/ruby/gems/1.9.1/gems/rake-0.9.0/lib/rake/rdoctask.rb:20:in `require'
C:/Ruby192/lib/ruby/gems/1.9.1/gems/rake-0.9.0/lib/rake/rdoctask.rb:20:in `<top (required)>'
C:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.0.7/lib/rails/tasks/documentation.rake:1:in `require'
C:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.0.7/lib/rails/tasks/documentation.rake:1:in `<top (required)>'
C:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.0.7/lib/rails/tasks.rb:15:in `load'
C:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.0.7/lib/rails/tasks.rb:15:in `block in <top (required)>'
C:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.0.7/lib/rails/tasks.rb:6:in `each'
C:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.0.7/lib/rails/tasks.rb:6:in `<top (required)>'
C:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.0.7/lib/rails/application.rb:214:in `require'
C:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.0.7/lib/rails/application.rb:214:in `initialize_tasks'
C:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.0.7/lib/rails/application.rb:139:in `load_tasks'
C:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.0.7/lib/rails/application.rb:77:in `method_missing'
C:/Users/USER1/rails_project/demo_app/Rakefile:7:in `<top (required)>'
C:/Ruby192/lib/ruby/1.9.1/rake.rb:2373:in `load'
C:/Ruby192/lib/ruby/1.9.1/rake.rb:2373:in `raw_load_rakefile'
C:/Ruby192/lib/ruby/1.9.1/rake.rb:2007:in `block in load_rakefile'
C:/Ruby192/lib/ruby/1.9.1/rake.rb:2058:in `standard_exception_handling'
C:/Ruby192/lib/ruby/1.9.1/rake.rb:2006:in `load_rakefile'
C:/Ruby192/lib/ruby/1.9.1/rake.rb:1991:in `run'
C:/Ruby192/bin/rake:31:in `<main>'
我该如何解决这个问题?