創建對象
before_validation
after_validation
before_save
around_save
before_create
around_create
after_create
after_save
after_commit/after_rollback更新對象
before_validation
after_validation
before_save
around_save
before_update
around_update
after_update
after_save
after_commit/after_rollback刪除對象
before_destroy
around_destroy
after_destroy
after_commit/after_rollback