卸载 Devise gem 后遇到迁移问题答案

【问题标题】：Have trouble with migration after uninstalling Devise gem卸载 Devise gem 后遇到迁移问题
【发布时间】：2015-08-02 13:01:15
【问题描述】：

我尝试安装设计，但遇到了很多迁移问题，所以继续卸载 gem。我尝试运行 rake:db migrate、redo、reset 和 drop，即使没有 Devise，我仍然会收到此错误：

/Users/ashleighalmeida/mixi/config/initializers/devise.rb:3:in `<top (required)>': uninitialized constant Devise (NameError)
    from /Users/ashleighalmeida/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/railties-4.2.1/lib/rails/engine.rb:652:in `block in load_config_initializer'
    from /Users/ashleighalmeida/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/activesupport-4.2.1/lib/active_support/notifications.rb:166:in `instrument'
    from /Users/ashleighalmeida/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/railties-4.2.1/lib/rails/engine.rb:651:in `load_config_initializer'
    from /Users/ashleighalmeida/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/railties-4.2.1/lib/rails/engine.rb:616:in `block (2 levels) in <class:Engine>'
    from /Users/ashleighalmeida/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/railties-4.2.1/lib/rails/engine.rb:615:in `each'
    from /Users/ashleighalmeida/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/railties-4.2.1/lib/rails/engine.rb:615:in `block in <class:Engine>'
    from /Users/ashleighalmeida/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/railties-4.2.1/lib/rails/initializable.rb:30:in `instance_exec'
    from /Users/ashleighalmeida/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/railties-4.2.1/lib/rails/initializable.rb:30:in `run'
    from /Users/ashleighalmeida/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/railties-4.2.1/lib/rails/initializable.rb:55:in `block in run_initializers'
    from /Users/ashleighalmeida/.rbenv/versions/2.1.5/lib/ruby/2.1.0/tsort.rb:226:in `block in tsort_each'
    from /Users/ashleighalmeida/.rbenv/versions/2.1.5/lib/ruby/2.1.0/tsort.rb:348:in `block (2 levels) in each_strongly_connected_component'
    from /Users/ashleighalmeida/.rbenv/versions/2.1.5/lib/ruby/2.1.0/tsort.rb:418:in `block (2 levels) in each_strongly_connected_component_from'
    from /Users/ashleighalmeida/.rbenv/versions/2.1.5/lib/ruby/2.1.0/tsort.rb:427:in `each_strongly_connected_component_from'
    from /Users/ashleighalmeida/.rbenv/versions/2.1.5/lib/ruby/2.1.0/tsort.rb:417:in `block in each_strongly_connected_component_from'
    from /Users/ashleighalmeida/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/railties-4.2.1/lib/rails/initializable.rb:44:in `each'
    from /Users/ashleighalmeida/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/railties-4.2.1/lib/rails/initializable.rb:44:in `tsort_each_child'
    from /Users/ashleighalmeida/.rbenv/versions/2.1.5/lib/ruby/2.1.0/tsort.rb:411:in `call'
    from /Users/ashleighalmeida/.rbenv/versions/2.1.5/lib/ruby/2.1.0/tsort.rb:411:in `each_strongly_connected_component_from'
    from /Users/ashleighalmeida/.rbenv/versions/2.1.5/lib/ruby/2.1.0/tsort.rb:347:in `block in each_strongly_connected_component'
    from /Users/ashleighalmeida/.rbenv/versions/2.1.5/lib/ruby/2.1.0/tsort.rb:345:in `each'
    from /Users/ashleighalmeida/.rbenv/versions/2.1.5/lib/ruby/2.1.0/tsort.rb:345:in `call'
    from /Users/ashleighalmeida/.rbenv/versions/2.1.5/lib/ruby/2.1.0/tsort.rb:345:in `each_strongly_connected_component'
    from /Users/ashleighalmeida/.rbenv/versions/2.1.5/lib/ruby/2.1.0/tsort.rb:224:in `tsort_each'
    from /Users/ashleighalmeida/.rbenv/versions/2.1.5/lib/ruby/2.1.0/tsort.rb:205:in `tsort_each'
    from /Users/ashleighalmeida/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/railties-4.2.1/lib/rails/initializable.rb:54:in `run_initializers'
    from /Users/ashleighalmeida/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/railties-4.2.1/lib/rails/application.rb:352:in `initialize!'
    from /Users/ashleighalmeida/mixi/config/environment.rb:5:in `<top (required)>'
    from /Users/ashleighalmeida/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/spring-1.3.6/lib/spring/application.rb:92:in `preload'
    from /Users/ashleighalmeida/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/spring-1.3.6/lib/spring/application.rb:143:in `serve'
    from /Users/ashleighalmeida/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/spring-1.3.6/lib/spring/application.rb:131:in `block in run'
    from /Users/ashleighalmeida/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/spring-1.3.6/lib/spring/application.rb:125:in `loop'
    from /Users/ashleighalmeida/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/spring-1.3.6/lib/spring/application.rb:125:in `run'
    from /Users/ashleighalmeida/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/spring-1.3.6/lib/spring/application/boot.rb:18:in `<top (required)>'
    from /Users/ashleighalmeida/.rbenv/versions/2.1.5/lib/ruby/site_ruby/2.1.0/rubygems/core_ext/kernel_require.rb:54:in `require'
    from /Users/ashleighalmeida/.rbenv/versions/2.1.5/lib/ruby/site_ruby/2.1.0/rubygems/core_ext/kernel_require.rb:54:in `require'
    from -e:1:in `<main>'

如何从迁移中完全删除 Devise？谢谢！

【问题讨论】：

标签： ruby-on-rails ruby devise

【解决方案1】：

您好像忘记删除 Devise 初始化程序，它位于此处：

config/initializers/devise.rb

【讨论】：

嘿，谢谢，我去手动删除它，尝试 rake:db:migrate 并得到相同的错误，但使用未定义的方法 `devise_for' #<:routing::mapper:0x007fc97efbdcc8> ( NoMethodError) 在顶部 :(
@icecreamrabbit 现在转到您的config/routes.rb 并删除设计路线:) 会有一个字符串，类似于devise_for :users
现在我得到：SQLite3::SQLException：重复列名：电子邮件：ALTER TABLE "users" ADD "email" varchar DEFAULT '' NOT NULL/Users/ashleighalmeida/mixi/db/migrate/20150802125451_add_devise_to_users .rb:5:in block in up' /Users/ashleighalmeida/mixi/db/migrate/20150802125451_add_devise_to_users.rb:3:in up' -e:1:in <main>' ActiveRecord::StatementInvalid: SQLite3::SQLException: duplicate column name: email: ALTER TABLE "users" ADD "email" varchar DEFAULT '' NOT NULL /Users/ashleighalmeida/mixi/db/migrate/20150802125451_add_devise_to_uup' + 更多列表 ;( 谢谢你
@icecreamrabbit 不知道该说什么，错误说明了一切，您想将现有列添加到表中。如果这是您的游乐场，请尝试重建您的数据库，follow these instructions。