Validating uniqueness of nested instance's attribute using accepts_nested_attributes_for

Question

I'm creating a polling system. I would like all options to be made unique, but only within their respective Poll . I'm using a proc to validate that they are not blank:

class Poll < ActiveRecord::Base
  has_many :options

  accepts_nested_attributes_for :options, reject_if: proc { |attributes| attributes['option'].blank? }
end

But I'm not sure how to validate their uniqueness. I tried doing it within the Option model but it's not rejecting duplicate options created through the Poll form's f.fields_for :

class Option < ActiveRecord::Base
  belongs_to :poll

  validates_uniqueness_of :option, scope: :poll_id
end

Is it possible to do it with proc ?

Answer 1

对选项属性（例如validates_uniqueness_of :title, :other, scope: :poll_id应用唯一性验证

Answer 2

You can pass any condition to that proc. So you could do query for that column and see whether any results are returned and reject if it they are.