python - DRF 3 - 使用表创建多对多更新/创建序列化程序

Question

我正在尝试在 DRF 3 中创建一个引用应用程序来演示可以创建/更新模型的嵌套序列化程序。在尝试创建嵌套模型时，下面的示例代码用“*create() argument after ** must be a mapping, not list*”轰炸。我也不清楚我将如何处理 .update()，因为在某些情况下我只想建立额外的关系(人)。

示例模型:

from django.db import models
class Person(models.Model):
    name = models.CharField(max_length=128)
class Group(models.Model):
    name = models.CharField(max_length=128)
    persons = models.ManyToManyField(Person, through='Membership')
class Membership(models.Model):
    person = models.ForeignKey(Person)
    group = models.ForeignKey(Group)

以及序列化器和 View 集:

from rest_framework.serializers import ModelSerializer
from rest_framework.viewsets import ModelViewSet
from app.models import Group, Person
class PersonSerializer(ModelSerializer):
    class Meta:
        model = Person
class GroupSerializer(ModelSerializer):
    persons = PersonSerializer(many=True)
    def create(self, validated_data):
        persons = validated_data.pop('persons')
        group = Group.objects.create(**validated_data)
        if persons: # Bombs without this check
            Person.objects.create(group=group, **persons)  # Errors here
        return group
    class Meta:
        model = Group

class PersonModelViewSet(ModelViewSet):
    serializer_class = PersonSerializer
    queryset = Person.objects.all()

class GroupModelViewSet(ModelViewSet):
    serializer_class = GroupSerializer
    queryset = Group.objects.all()

我正在尝试发布一些 JSON，插入一个包含两个(相关)人员的组:

{
   "persons": [
      { "name" : "name 1" },
      { "name" : "name 2" }
   ],
   "name": "group name 1"
}

Answer 1

我不知道是否有更简单的方法，但我设法让它工作的唯一方法是在组序列化程序中引用“直通”模型“成员资格”，并为 .create() 和编写自定义代码。更新()。这似乎只是设置 M2M FK 的大量工作。如果有人知道更好的方法，我很乐意听到。

class GroupMembershipSerializer(ModelSerializer):
    class Meta:
        model = Membership
        fields = ('person',)

class GroupCreateSerializer(ModelSerializer):
     memberships = GroupMembershipSerializer(many=True, required=False)

    def create(self, validated_data):
        person_data = validated_data.pop('memberships')
        group = Group.objects.create(**validated_data)
        for person in person_data:
            d=dict(person)
            Membership.objects.create(group=group, person=d['person'])
        return group

    def update(self, instance, validated_data):
        person_data = validated_data.pop('memberships')
        for item in validated_data:
            if Group._meta.get_field(item):
                setattr(instance, item, validated_data[item])
        Membership.objects.filter(group=instance).delete()
        for person in person_data:
            d=dict(person)
            Membership.objects.create(group=instance, person=d['person'])
        instance.save()
        return instance

    class Meta:
        model = Group

class GroupCreateModelViewSet(ModelViewSet):
    serializer_class = GroupCreateSerializer
    queryset = Group.objects.all()

因此您可以使用相关人员创建一个新组:

 { 
     "name" : "Group 1", 
     "memberships" : [ 
         { "person" : 1 },
         { "person" : 2 }
     ]
 }