如何仅向singleton_class添加验证？

Question

当我向singleton_class添加验证时，它似乎被分配给基类而且它也没有触发。

class Example
  attr_accessor :title, :some_boolean
  include ActiveModel::Validations
end


puts Example.validators  # []

with_validations = Example.new
with_validations.singleton_class.send :validates, :title, :presence => true

puts with_validations.valid?  #true

puts Example.validators.length # 1

我想发生什么：

with_validations.valid?  # false
Example.new.valid?       # true

Answer 1

您可以使用“开启”选项进行验证。

validates :title, presence: true, on: :draft

example = Example.new
example.valid? # true
example.valid?(:draft) #false