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[英](pymysql.err.IntegrityError) (1451, 'Cannot delete or update a parent row: a foreign key constraint fails…') in Flask
[英]IntegrityError: (1451, 'Cannot delete or update a parent row: a foreign key constraint fails (..))
使用 schedule_files 刪除用戶時,我得到了這個:
IntegrityError在/管理/認證/用戶/ 166 /刪除/(1451, '不能刪除或更新父行,外鍵約束失敗(
vacation
。vacations_schedulefile
,約束vacations_schedulefile_user_id_e85fa52f_fk_auth_user_id
外鍵(user_id
)參考auth_user
(id
))')
我的模型是:
class ScheduleFile(models.Model):
user = models.ForeignKey(User, on_delete=models.CASCADE)
added = models.DateTimeField(default=django.utils.timezone.now)
def __str__(self):
return '[User ID: {}] {}'.format(str(self.user.id), self.user.username)
並且
class VacationEvent(models.Model):
user = models.ForeignKey(User, on_delete=models.CASCADE)
schedule_type = models.CharField(choices=SCHEDULE_TYPES, default=STRICT_TIME, max_length=3)
exclude_fba_from_chatzos = models.BooleanField(default=False)
schedule_file = models.ForeignKey(ScheduleFile, on_delete=models.CASCADE, null=True)
status = models.CharField(verbose_name="status event", choices=EVENT_STATUSES, max_length=3, default=CREATED)
而 User(AbstractUser) 我決定創建 pre_delete 信號並刪除調度模型的相關對象:
@receiver(pre_delete, dispatch_uid='User')
def user_del(sender, instance, **kwargs):
i = instance
events = VacationEvent.objects.filter(user_id=166)
schedule = prefetch_related_objects(events, 'schedule_file__user')
schedule.delete()
# instance.user.schedulefile_set.clear()
# qs = VacationEvent.objects.filter(user_id=166).prefetch_related_('schedule_file')
# qs.delete()
# b = ScheduleFile.objects.filter(user_id=166)
# e = VacationEvent.objects.filter(user_id=166)
# e.schedule_file.remove(b)
但它返回 'NoneType' 對象沒有屬性 'delete'。 我怎樣才能做對? 謝謝你的幫助。
您不能刪除 ScheduleFile,因為 VacationEvent 需要它的主鍵,因此您必須在 ScheduleFile 模型之前刪除 VacationEvent 記錄,這可以通過信號或覆蓋 ScheduleFile 模型上的刪除功能以多種方式完成
例子:
def delete(self, using=None):
if self.schedule_file:
self.schedule_file.delete()
super(ScheduleFile, self).delete(using)
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