Question

我的网站上有一个测试对象，试图将其正确地插入数据库。这是带有嵌套产品数据的订单对象。这是前端发布JSON的示例：

{
    "phone": "123456789",
    "first_name": "name",
    "delivery_date": "2020-01-06",
    "delivery_time": 2,
    "address": "address",
    "comment": "comment",
    "payment": 0,
    "order_items": [
      {
        "quantity": 2,
        "pizza": 1
      },
      {
        "quantity": 3,
        "pizza": 2
      }
    ]
}

这是我的serializers.py

class OrderItemSerializer(serializers.ModelSerializer):
    quantity = serializers.IntegerField()
    pizza = serializers.SerializerMethodField()
    print(pizza, quantity)

    def get_pizza(self, obj):
        print(obj.pizza.id)
        return obj.pizza.id

    class Meta:
        model = OrderItem
        fields = ('quantity',
                  'pizza',)


class OrderSerializer(serializers.ModelSerializer):
    order_items = serializers.SerializerMethodField()

    """
    Calculate order_items field 
    """
    def get_order_items(self, obj):
        items = obj.orderitem_set.all()
        print(obj)
        print(items)
        return OrderItemSerializer(items, many=True).data

    class Meta:
        model = Order
        fields = ('phone',
                  'first_name',
                  'delivery_date',
                  'delivery_time',
                  'address',
                  'comment',
                  'payment',
                  'order_items',)

结果，order_items始终为空： "order_items": []

我正在使用Swagger测试和记录API。我可以直接从那里发布订单，没有错误，但是即使手动添加订单项目，它们也不会出现在服务器响应正文中。这必须表示我没有正确处理嵌套对象。

POST

{
    "phone": "123456",
    "first_name": "string",
    "delivery_date": "2000-10-21",
    "delivery_time": 2,
    "address": "string",
    "comment": "string",
    "payment": 0,
    "order_items": [
        {"pizza": 2,"quantity": 3},
        {"pizza": 1,"quantity": 4}]
}

201，响应正文：

{
  "phone": "123456",
  "first_name": "string",
  "delivery_date": "2000-10-21",
  "delivery_time": 2,
  "address": "string",
  "comment": "string",
  "payment": 0,
  "order_items": []
}

我还在上面的代码中设置了一些print行，看来OrderItemSerializer根本没有被使用。 get_order_items打印订单ID和一个空数组，而get_pizza在网站上进行订单时不打印任何内容。

Answer 1

您需要重写序列化程序的create()方法来制作writable nested serializers。

尝试这样的事情：

class OrderSerializer(serializers.ModelSerializer):
    order_items = serializers.SerializerMethodField()

    """
    Calculate order_items field 
    """
    def get_order_items(self, obj):
        items = obj.orderitem_set.all()
        print(obj)
        print(items)
        return OrderItemSerializer(items, many=True).data

    class Meta:
        model = Order
        fields = ('phone',
                  'first_name',
                  'delivery_date',
                  'delivery_time',
                  'address',
                  'comment',
                  'payment',
                  'order_items',)

    def create(self, validated_data):
        items_data = validated_data.pop('order_items')
        order = Order.objects.create(**validated_data)
        for item_data in items_data:
            OrderItem.objects.create(order=order, **item_data)
        return order

此外，您可以仅将OrderItemSerializer用作字段，而不使用SerializerMethodField。您可以使用source参数指定字段source：

order_items = serializers.OrderItemSerializer(many=True, source="orderitem_set")

Answer 2

最终我想到了这个。我必须向order_items对象添加一个Order变量，该变量没有以任何方式使用，只是浪费了DB中的空间。即使这不是很大的浪费，但在任何情况下我都不认为这是编写代码的好方法。

如果有人可以在评论或其他答案中提出更好的建议，我也会尝试一下。

from rest_framework import serializers
from .models import Order, OrderItem
import copy


class OrderItemSerializer(serializers.ModelSerializer):
    class Meta:
        model = OrderItem
        fields = ('quantity',
                  'pizza',)


class OrderSerializer(serializers.ModelSerializer):
    order_items = OrderItemSerializer(many=True)

    class Meta:
        model = Order
        fields = ('phone',
                  'first_name',
                  'delivery_date',
                  'delivery_time',
                  'address',
                  'comment',
                  'payment',
                  'order_items')

    def create(self, validated_data, **kwargs):
        for_items = copy.deepcopy(validated_data)

        # create order object
        del validated_data['order_items']
        print('VALID', validated_data)
        order = Order.objects.create(**validated_data)

        # create order items
        for item in for_items.pop('order_items'):
            order_item = dict(item.items())
            print('ITEM', order_item)
            OrderItem.objects.create(order=order, **order_item)

        return order

在DRF中序列化嵌套对象

2 个答案: