我有一个验证,看起来像这样：
class Book < ActiveRecord::Base
belongs_to :author
validates :name,uniqueness: { scope: :author_id }
end
解决方法
是的,有一个
Proc和：除非在验证器上.
class Book < ActiveRecord::Base
belongs_to :author
validates :name,uniqueness: { scope: :author_id },unless: Proc.new { |b| b.author_id.blank? }
end
推荐阅读：http://guides.rubyonrails.org/active_record_validations.html#using-a-proc-with-if-and-unless