mysql - Ruby on Rails has_one 模型不提供 ID 列

Question

我有一个旧版 Rails(版本 1.2.3)应用程序，它在许多服务器上运行没有问题(更不用说我的本地环境)。不过，部署到最新的服务器后，我现在收到 ActiveRecord::StatementInvalid: Mysql::Error: #23000Column 'video_id' can not be null 错误。

以下是简化的模型/关系:

class Video < ActiveRecord::Base
    has_one(:user, :dependent => :destroy)
end

class User < ActiveRecord::Base
    belongs_to(:video)
end

下面是失败关系的 Rails 控制台记录:

>> video = Video.create(:title => 'New Video')
=> #<Video:0xb6d5e31c>...
>> video.id
=> 5
>> video.user = User.create(:name => 'Tester')
ActiveRecord::StatementInvalid: Mysql::Error: #23000Column 'video_id' cannot be null: INSERT INTO users (`name`, `video_id`) VALUES('Tester', NULL)
    from /usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/connection_adapters/abstract_adapter.rb:128:in `log'
    from /usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/connection_adapters/mysql_adapter.rb:243:in `execute'
    from /usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/connection_adapters/mysql_adapter.rb:253:in `insert'
    from /usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/base.rb:1811:in `create_without_callbacks'
    from /usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/callbacks.rb:254:in `create_without_timestamps'
    from /usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/timestamp.rb:39:in `create'
    from /usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/base.rb:1789:in `create_or_update_without_callbacks'
    from /usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/callbacks.rb:242:in `create_or_update'
    from /usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/base.rb:1545:in `save_without_validation'
    from /usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/validations.rb:752:in `save_without_transactions'
    from /usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/transactions.rb:129:in `save'
    from /usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/connection_adapters/abstract/database_statements.rb:59:in `transaction'
    from /usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/transactions.rb:95:in `transaction'
    from /usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/transactions.rb:121:in `transaction'
    from /usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/transactions.rb:129:in `save'
    from /usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/base.rb:451:in `create'
    from (irb):3
    from :0

还有其他人遇到过 ActiveRecord 在明确知道 ID 的情况下却没有发送 ID 的情况吗？

Answer 1

正确的语法是

video.user.create(:name => 'Tester')

如您所见，它会尝试根据 ruby​​ 的评估顺序创建用户，然后将其分配给 video.user。