Django Rest框架序列化器不打印嵌套关系

Question

我已经建立了Order和OrderLine两个模型之间的关系。我已经按照DRF文档为它们创建了序列化器，但是当打印serializer.data时，嵌套的对象没有显示。

这些是我的模型:

class Order(models.Model):
id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
session_id = models.CharField(max_length=256)  
class OrderLine(models.Model):
order_id = models.ForeignKey(Order, on_delete=models.DO_NOTHING)
product_id = models.ForeignKey(Product, on_delete=models.DO_NOTHING)
price = models.DecimalField(decimal_places=2, max_digits=20)
quantity = models.IntegerField()
total = models.DecimalField(decimal_places=2, max_digits=20)

created_at = models.DateField(auto_now_add=True)
updated_at = models.DateField(auto_now=True)

这些是序列化器:

from rest_framework import serializers
from .models import Order, OrderLine

class OrderLineSerializer(serializers.ModelSerializer):
"""
OrderLine serializer
"""
class Meta:
model = OrderLine
fields = ['product_id', 'price', 'quantity', 'total']


class OrderSerializer(serializers.ModelSerializer):
"""
Order serializer
"""
items = OrderLineSerializer(many=True, read_only=True)
class Meta:
model = Order
fields = ['session_id', 'subtotal', 'total', 'items']
read_only_fields = ['id']

，这是视图:

class OrderAPIViewSet(viewsets.ViewSet):
def create(self, request):
order = Order.objects.create(session_id=request.data['session_id'])
for item in request.data['items']:
product = Product.objects.get(pk=item['product_id'])
total = Decimal(item['price'] * item['quantity']) 
OrderLine.objects.create(
order_id=order,
product_id=product,
price=Decimal(item['price']),
quantity=item['quantity'],
total=total
)
serializer = OrderSerializer(instance=order)
print("HERE")
print(serializer.data)
return Response(status=status.HTTP_200_OK)

从我的REST客户端，我张贴以下对象:

{
"session_id":uuid,
"items": [
{
"product_id": product.id,
"price": 5.80,
"quantity": 2,
}
]

}

但是当视图中的print语句被执行时，打印的内容是:

{
"session_id":"4def7bdb-dedb-46aa-9c70-1d9e4f522149",
"subtotal":"0.00",
"total":"0.00"
}

注意items子资源没有被包含。

我错过了什么?

Answer 1

因为您将read_only=True参数传递给OrderLineSerializer。当序列化器的内置方法to_internal_value()运行时，清除字段列表中不包含的数据。查看更多详细信息:read_only