[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 删除用户时,我得到了这个:
IntegrityError在/管理/认证/用户/ 166 /删除/(1451, '不能删除或更新父行,外键约束失败(
vacation
。vacations_schedulefile
,约束vacations_schedulefile_user_id_e85fa52f_fk_auth_user_id
外键(user_id
)参考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)
并且
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) 我决定创建 pre_delete 信号并删除调度模型的相关对象:
@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' 对象没有属性 'delete'。 我怎样才能做对? 谢谢你的帮助。
您不能删除 ScheduleFile,因为 VacationEvent 需要它的主键,因此您必须在 ScheduleFile 模型之前删除 VacationEvent 记录,这可以通过信号或覆盖 ScheduleFile 模型上的删除功能以多种方式完成
例子:
def delete(self, using=None):
if self.schedule_file:
self.schedule_file.delete()
super(ScheduleFile, self).delete(using)
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