如何使用update函数在嵌套序列化器Django中添加或删除对象

Question

我有2个模型-模块和房间。一个模块可以有零个或多个房间，一个房间可以添加到多个模块中。因此，它们之间存在简单的多对多关系。

在使用put请求更新模块字段时，我不想更新其中的任何房间，我只想在模块中添加/删除房间。这是我的文件-

模块/models.py -

class Module(models.Model):
module_id = models.AutoField(primary_key=True)
title = models.CharField(max_length=100)
desc = models.TextField()
rooms = models.ManyToManyField(Rooms)

房间/models.py -

class Rooms(models.Model):
room_id = models.AutoField(primary_key=True)
title = models.CharField(max_length=100)
desc = models.TextField()
level = models.CharField(max_length=100)
is_deleted = models.BooleanField(default=False)

模块/serializers.py -

class ModuleSerializer(serializers.ModelSerializer):
rooms = RoomSerializer(read_only=True, many=True)
class Meta:
model = Module
fields = "__all__"
def create(self, validated_data):
rooms_data = validated_data.pop('rooms')
module = Module.objects.create(**validated_data)
for data in rooms_data:
room, created = Rooms.objects.get_or_create(**data)
module.rooms.add(room)
return module

房间/serialier.py -

class RoomSerializerWrite(serializers.ModelSerializer):
room_id = serializers.IntegerField()
class Meta:
model = Rooms
fields = "__all__"

模块/views.py -

class add_module(APIView):
def post(self, request, format=None):
module_serializer = ModuleSerializer(data=request.data)
if module_serializer.is_valid():
module_serializer.save()
return Response(module_serializer.data['module_id'], status = status.HTTP_201_CREATED)
return Response(module_serializer.errors, status = status.HTTP_400_BAD_REQUEST)

POST请求正文，用于在POSTMAN中更新一个模块-

{
"module_id": 2,
"rooms": [
{
"room_id": 2,
"title": "4",
"desc": "22",
"level": "2",
}
],
"title": "4",
"desc": "22",
}

有人能帮我在模块/序列化器的更新功能?

Answer 1

我所理解的是你不想用你的帖子来更新你的模块的房间，实际上你想要替换它们。所以只要从m2m关系中清除每个房间并从请求中添加新房间即可。类似的;

def update(self, instance, validated_data):
# get new rooms
rooms_data = validated_data.get('rooms')

# clear m2m relationship
instance.rooms_set.clear()

# I assume your rooms_data is a list that contains dicts with room fields
for room_data in rooms_data:
# get room instance
room, created = Rooms.objects.get_or_create(**room_data)

# Add it to m2m relationship
instance.rooms.add(room)
instance.save()
return instance

因此，如果您不发送现有的房间到您的序列化器，它将在实例上从m2m关系中删除。