Question

这里的第一篇帖子对任何小说都道歉。我正在通过关于C9的Lynda.com Ruby on Rails 5 Essential培训工作，并且遇到了一个问题，试图迁移回到＆＃39; VERSION：0＆＃39;有这个错误消息：

导轨中止了！不知道如何建立任务＆＃39; VERSION：0＆＃39; （见--tasks） /usr/local/rvm/gems/ruby-2.3.1/gems/railties-5.1.2/lib/rails/commands/rake/rake_command.rb:21:in block in perform' /usr/local/rvm/gems/ruby-2.3.1/gems/railties-5.1.2/lib/rails/commands/rake/rake_command.rb:18:in表演＆＃39; /usr/local/rvm/gems/ruby-2.3.1/gems/railties-5.1.2/lib/rails/command.rb:46:in invoke' /usr/local/rvm/gems/ruby-2.3.1/gems/railties-5.1.2/lib/rails/commands.rb:16:in＆＃39; / home / ubuntu / workspace / bin / rails：9：require' /home/ubuntu/workspace/bin/rails:9:in＆＃39; /usr/local/rvm/gems/ruby-2.3.1/gems/spring-2.0.2/lib/spring/client/rails.rb:28:in load' /usr/local/rvm/gems/ruby-2.3.1/gems/spring-2.0.2/lib/spring/client/rails.rb:28:in来电＆＃39; /usr/local/rvm/gems/ruby-2.3.1/gems/spring-2.0.2/lib/spring/client/command.rb:7:in call' /usr/local/rvm/gems/ruby-2.3.1/gems/spring-2.0.2/lib/spring/client.rb:30:in run＆＃39; /usr/local/rvm/gems/ruby-2.3.1/gems/spring-2.0.2/bin/spring:49:in <top (required)>' /usr/local/rvm/gems/ruby-2.3.1/gems/spring-2.0.2/lib/spring/binstub.rb:31:in load＆＃39; /usr/local/rvm/gems/ruby-2.3.1/gems/spring-2.0.2/lib/spring/binstub.rb:31:in <top (required)>' /home/ubuntu/workspace/bin/spring:15:in要求＆＃39; / home / ubuntu / workspace / bin / spring：15：<top (required)>' bin/rails:3:in加载＆＃39; bin / rails：3：在`＆＃39;

非常感谢任何帮助或建议

Answer 1

在Rails中进行迁移时，您可以执行以下操作：

rake db:migrate，它会将您的新迁移迁移到database并将其添加到scheme.rb。

您还可以执行rake db:rollback，回滚上次迁移。

对于回滚，您还可以执行rake db:rollback STEP=n，这将回滚n次迁移，其中n是您要回滚的最近迁移次数。

如果您要回滚版本的迁移，则应将迁移版本应用为：rake db:migrate VERSION=0 （如@sjudge在评论中所述）

您也可以rake db:migrate:redo。

还有其他一些迁移，例如：

rake db:migrate:redo STEP=n
rake db:migrate:up VERSION=20080906120000
rake db:migrate:down VERSION=20080906120000

rails无法迁移：＆＃34;不知道如何构建任务VERSION：0＆＃34;

1 个答案: