Django得到一个外键 [英] Django get count on a ForeignKey
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问题描述
我需要获得属于组的所有联系人的总计数,但是从名为批量的模型中获取...
这将有助于解释
模型(未显示) / p>
class Batch(models.Model):
#FK
group = models.ForeignKey(Group,null = true,blank = True
class Group(models.Model):
name = models.CharField(max_length = 60)
class Contact(models.Model):
first_name = models.CharField(max_length = 60)
group = models.ForeignKey(Group)
所以在批量内我想做这样的事情....
$ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $
但是,由于小组的关系其他方式,我正在努力奋斗。
任何选项?
解决方案
return self.group.contact_set.count()
I need to get the total count of all contacts that belong to a group, but from within the model called batch....
This will help explain
models (not shown in full)
class Batch(models.Model):
#FK
group = models.ForeignKey(Group, null=True, blank=True)
class Group(models.Model):
name = models.CharField(max_length=60)
class Contact(models.Model):
first_name = models.CharField(max_length=60)
group = models.ForeignKey(Group)
So within batch I want to do something like this....
def get_contact_count(self):
return len(self.group.contacts)
But as group has the relationship the other way around I'm struggling.
Any options?
解决方案
return self.group.contact_set.count()
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