脚手架后无法迁移数据库。2.2节Ruby on Rails教程Michael Hartl

Question

我正在阅读Hartl ruby on rails教程（第2.2节），而在迁移数据库时遇到了麻烦。一切似乎都正常，然后我运行rails generate scaffold User name:string email:string 之后，我尝试运行包exec rake db：migrate并收到以下错误消息：

$ bundle exec rake db:migrate

                                                                                 == 20141125234257 CreateUsers: migrating ======================================

-- create_table(:users)

   -> 0.0079s

== 20141125234257 CreateUsers: migrated (0.0080s) =============================

rake aborted!

StandardError: An error has occurred, this and all later migrations canceled:

wrong number of arguments (1 for 0)/usr/local/rvm/gems/ruby-2.1.4@rails4/gems/activerecord-4.2.0.beta4/lib/active_record/connection_adapters/abstract_adapter.rb:271:in `initialize'

/usr/local/rvm/gems/ruby-2.1.4@rails4/gems/activerecord-4.2.0.beta4/lib/active_record/connection_adapters/abstract_adapter.rb:271:in `new'

/usr/local/rvm/gems/ruby-2.1.4@rails4/gems/activerecord-4.2.0.beta4/lib/active_record/connection_adapters/abstract_adapter.rb:271:in `substitute_at'

/usr/local/rvm/gems/ruby-2.1.4@rails4/gems/activerecord-4.2.0.beta4/lib/active_record/relation.rb:97:in `block in substitute_values'

/usr/local/rvm/gems/ruby-2.1.4@rails4/gems/activerecord-4.2.0.beta4/lib/active_record/relation.rb:96:in `each'

/usr/local/rvm/gems/ruby-2.1.4@rails4/gems/activerecord-4.2.0.beta4/lib/active_record/relation.rb:96:in `each_with_index'

/usr/local/rvm/gems/ruby-2.1.4@rails4/gems/activerecord-4.2.0.beta4/lib/active_record/relation.rb:96:in `substitute_values'

/usr/local/rvm/gems/ruby-2.1.4@rails4/gems/activerecord-4.2.0.beta4/lib/active_record/relation.rb:56:in `insert'

/usr/local/rvm/gems/ruby-2.1.4@rails4/gems/activerecord-4.2.0.beta4/lib/active_record/persistence.rb:521:in `_create_record'

/usr/local/rvm/gems/ruby-2.1.4@rails4/gems/activerecord-4.2.0.beta4/lib/active_record/counter_cache.rb:139:in `_create_record'

Tasks: TOP => db:migrate

(See full trace by running task with --trace)

我尝试返回到较早的提交，然后再次运行所有内容，但收到相同的错误消息。我是否还应该添加其他文件来帮助解决此问题？

Answer 1

以上更改gemfile的解决方案。 gem 'arel', '6.0.0.beta2'我收到以下错误消息。You have requested:arel = 6.0.0.beta2The bundle currently has arel locked at 6.0.0.Try running `bundle update arel`后bundle update arel    有效

Answer 2

我已经解决了rake db:reset之后rake db:migrate工作了。