Question

鉴于此：

class User < ActiveRecord::Base
  has_many :photos
  MAX_PHOTOS = 5
  validate :quantity_of_photos

  def quantity_of_photos
    ???
  end
end

而且：

@user.photos.size  # => 5

我需要这个失败：

@user.photos << Photo.create(valid_photo_attributes)

我该如何进行验证？

Answer 1

将照片数量方法移动到照片模型：

class Photo < ActiveRecord::Base

   belongs_to :user
   validates :quantity_of_photos

    def quantity_of_photos
      if new_record? && user.photos.size >= User::MAX_PHOTOS
        errors.add_to_base "You cannot have more than #{MAX_PHOTOS} photos."
      end
    end

end

ActiveRecord实例的有效性取决于它的错误数组中是否存在错误。

验证关联对象的数量

1 个答案: