为什么我会收到“Unknown validator：’MessageValidator’”？

我收到这个错误

未知validation器：’MessageValidator’

我不知道为什么我会这样做。
我的代码出了什么问题？

validates :title, :presence => true, :uniqueness => true, :length => { :maximum => 100 }, :message => "Must be input and has to be less than 100 characters, and unique." 

Answer 1

尝试：

 validates :title, :presence => {:message => "Title can't be blank." }, :uniqueness => {:message => "Title already exists."}, :length => { :maximum => 100, :message => "Must be less than 100 characters"} 

Answer 2

我假设您希望消息在长度validation失败时出现。 您应该在该哈希中包含消息，如：

 validates :title, :presence => true, :uniqueness => true, :length => { :maximum => 100, :message => "Must be less than 100 characters"}