我在 django 中有一个信号回调:
@receiver(post_save, sender=MediumCategory)
def update_category_descendants(sender, **kwargs):
def children_for(category):
return MediumCategory.objects.filter(parent=category)
def do_update_descendants(category):
children = children_for(category)
descendants = list() + list(children)
for descendants_part in [do_update_descendants(child) for child in children]:
descendants += descendants_part
category.descendants.clear()
for descendant in descendants:
if category and not (descendant in category.descendants.all()):
category.descendants.add(descendant)
category.save()
return list(descendants)
# call it for update
do_update_descendants(None)
...但是在信号处理程序的主体中,我.save()
在同一模型上使用MediumCategory
。这会导致再次发送信号。我怎样才能禁用它?
完美的解决方案将是一个with
包含一些“魔法”的声明。
更新: 如果有人感兴趣,这是我的最终解决方案:
class MediumCategory(models.Model):
name = models.CharField(max_length=100)
slug = models.SlugField(blank=True)
parent = models.ForeignKey('self', blank=True, null=True)
parameters = models.ManyToManyField(AdvertisementDescriptonParameter, blank=True)
count_mediums = models.PositiveIntegerField(default=0)
count_ads = models.PositiveIntegerField(default=0)
descendants = models.ManyToManyField('self', blank=True, null=True)
def save(self, *args, **kwargs):
self.slug = slugify(self.name)
super(MediumCategory, self).save(*args, **kwargs)
def __unicode__(self):
return unicode(self.name)
(...)
@receiver(post_save, sender=MediumCategory)
def update_category_descendants(sender=None, **kwargs):
def children_for(category):
return MediumCategory.objects.filter(parent=category)
def do_update_descendants(category):
children = children_for(category)
descendants = list() + list(children)
for descendants_part in [do_update_descendants(child) for child in children]:
descendants += descendants_part
if category:
category.descendants.clear()
for descendant in descendants:
category.descendants.add(descendant)
return list(descendants)
# call it for update
do_update_descendants(None)