嵌套属性reject_if模型有四个以上的子项

Question

我有以下情况：

class Question < ActiveRecord::Base
  has_many :answers, :dependent => :destroy
  accepts_nested_attributes_for :answers, :allow_destroy => true, :reject_if => ""

end

class Answer < ActiveRecord::Base
  belongs_to :question
end

如果一个问题的答案超过4个，我怎能拒绝创作？

Answer 1

我希望它适合你。

class Question < ActiveRecord::Base
  has_many :answers, :dependent => :destroy
  accepts_nested_attributes_for :answers, :reject_if => -> {|q| q['answers'].count > 4}, :allow_destroy => true
end

class Answer < ActiveRecord::Base
 belongs_to :question
end