有没有办法在before_destroy钩子中检查哪个对象(类)被称为destroy?
在下面的例子中,当一个病人被摧毁时,他们的约会也是如此(这就是我想要的);但是,如果有任何与该医生相关的预约,我不想让医生被销毁.
再次,有没有办法在before_destory回调中进行这样的检查?如果没有,是否还有其他方法可以根据通话的“方向”(即根据谁打电话)完成“破坏检查”?
class Physician < ActiveRecord::Base has_many :appointments,dependent: :destroy has_many :patients,through: :appointments end class Patient < ActiveRecord::Base has_many :appointments,dependent: :destroy has_many :physicians,through: :appointments end class Appointment < ActiveRecord::Base belongs_to :patient belongs_to :physician before_destroy :ensure_not_referenced_by_anything_important private def ensure_not_referenced_by_anything_important unless patients.empty? errors.add(:base,'This physician cannot be deleted because appointments exist.') false end end end
解决方法
说啊:
class Physician < ActiveRecord::Base has_many :appointments,dependent: :restrict_with_exception has_many :patients,through: :appointments end
请注意dependent :: restrict_with_exception.这将导致Active Record拒绝销毁任何具有相关约会记录的医生记录.
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