ruby-on-rails - 未定义的方法 "each_pair"运行数据库迁移时出错

Question

这里是错误:

迁移代码:

class Test < ActiveRecord::Migration
  def change
    create_table :test do |t|
    end
  end
end

作为旁注，如果我删除“Create_table”调用，它不会失败。

在运行 rake db:migrate 时，我收到此错误消息:

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

undefined method `each_pair' for []:Array/Users/m/Apps/stream-web/db/migrate/20150329070040_test.rb:3:in `change'
NoMethodError: undefined method `each_pair' for []:Array
/Users/m/Apps/stream-web/db/migrate/20150329070040_test.rb:3:in `change'

如何解决这个问题？我正在使用“pg”gem，我的适配器是 postgresql。

完整跟踪错误:

undefined method `each_pair' for []:Array/Users/mingyeowng/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/activerecord-4.2.1/lib/active_record/connection_adapters/abstract/schema_statements.rb:216:in `create_table'
/Users/mingyeowng/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/schema_plus-1.8.5/lib/schema_plus/active_record/connection_adapters/schema_statements.rb:39:in `create_table_with_schema_plus'
/Users/mingyeowng/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/activerecord-4.2.1/lib/active_record/migration.rb:662:in `block in method_missing'
/Users/mingyeowng/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/activerecord-4.2.1/lib/active_record/migration.rb:632:in `block in say_with_time'
/Users/mingyeowng/.rbenv/versions/2.1.5/lib/ruby/2.1.0/benchmark.rb:279:in `measure'
/Users/mingyeowng/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/activerecord-4.2.1/lib/active_record/migration.rb:632:in `say_with_time'
/Users/mingyeowng/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/activerecord-4.2.1/lib/active_record/migration.rb:652:in `method_missing'
/Users/mingyeowng/Apps/stream-web/db/migrate/20150329070040_test.rb:3:in `change'

Answer 1

这取决于您正在使用的 schema_plus gem:rails 4.2.1 更改了它正在覆盖的方法的签名。

有一个fix在主分支上，但是这个 won't be backported到 1.x 系列的 gem，它不支持 rails 4.2 之后的版本。但是，您可以使用当前的 2.0.0 预发布版本。