我在使用外键访问相关模型中的字段时遇到了问题。
我有两个模型,Person和Party,如下所示:
class Person(models.Model):
title = models.CharField(max_length = 4, blank=True, null=True)
first = models.CharField(max_length = 30, blank=True, null=True)
last = models.CharField(max_length = 30, blank=True, null=True)
party = models.ForeignKey(Party, related_name = 'parties', on_delete=models.CASCADE, blank=True, null=True)
def __str__(self):
return self.id
class Party(models.Model):
party_name = models.CharField(max_length = 50)
party_code = models.CharField(max_length = 5)
def __str__(self):
return self.party_name
我在试着统计一下每个派对的人数。我希望结果看起来像这样:
[{
"party_name": "Democrat",
"total_members": 93
},
{
"party_name": "Republican",
"total_members": 32
},
{
"party_name": "Non-Partisan",
"total_members": 34
}]
我的序列化程序如下:
class CountPartiesSerializer(serializers.ModelSerializer):
total_members = serializers.IntegerField()
class Meta:
model = Person
fields = ('id', 'party', 'total_members')
我的观点如下:
class CountPartiesViewSet(DefaultsMixin, viewsets.ModelViewSet):
queryset = Person.objects.values('party__party_name').annotate(total_members = Count('id'))
serializer_class = CountPartiesSerializer
但这会导致以下结果:
[{
"party": null,
"total_members": 34
},
{
"party": null,
"total_members": 93
},
{
"party": null,
"total_members": 32
}]
我尝试了一百万种不同的方法,我知道我错过了一些东西,但我不知道如何让它工作。任何建议都将不胜感激!
发布于 2018-09-04 01:54:03
你序列化了错误的东西。您的序列化程序应该基于Party,然后您可以添加成员计数。
编辑
class PartySerializer(serializers.ModelSerializer):
total_members = serializers.IntegerField()
class Meta:
model = Party
fields = ('name', 'total_members')
class PartyViewSet(DefaultsMixin, viewsets.ModelViewSet):
queryset = Party.objects.values('name').annotate(total_members=Count('parties'))
serializer_class = PartySerializer
当然,您确实存在party和person之间的关系:这是您的外键的反向关系。请注意,您为那里的人员选择的名称很容易混淆;它应该是'people',或者只是将其保留为默认值,即‘related_name _related_name’。
https://stackoverflow.com/questions/52154090
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