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.
