Django 休息框架 |可写多重嵌套关系

Question

我有一些模型，它们相互嵌套。我想为 2 个序列化程序进行批量创建，它们都与其他模型有关系。我查看了DRF 上的文档，但无法在我的代码中实现它。

我这样发送我的 json 数据：

{
  'status':true,
  'products':[
              {
               'painting':{'amount':10}, 
               'product':{'id':12, }
              },
              {
               'painting':{'amount':10}, 
               'product':{'id':12, }
              }
             ],
   'customer':{ 'name':'Adnan',
                'address':{'country':'Turkey'}
              },
    'total':111

}

#models.py

class Address():
    ...
class Customer():
    address = models.ForeignKey(Address, ...)
class Painting():
    ...
class Product():
    ...
class Selling():
    customer = models.ForeignKey(Customer, ...)
    products = models.ManyToManyField(Product, through='SellingProduct')
class SellingProduct():
    selling = models.ForeignKey(Selling, ...)
    product = models.ForeignKey(Product, ...)
    painting = models.ForeignKey(Painting, ...)

这是我的serializers.py

class AddressSerializer():
    ...
class CustomerSerializer():
    address = AddressSerializer()
    ...
class PaintingSerializer():
    ...
class ProductSerializer():
    ...
class SellingProductSerializer():
    painting = PaintingSerializer()
    product = ProductSerializer()

class SellingSerializer():
    customer = CustomerSerializer()
    products = SellingProductSerializer(many=True)
    ...
    def create(self, validated_data):
        ...

如果我这样写：

class SellingSerializer():
    ...
    def create(self, validated_data):
        customer_data = validated_data.pop('customer')
        products_data = validated_data.pop('products')
        selling = Selling.objects.create(**validated_data) #i didn't pass customer here
        for product_data in products_data:
            SellingProducts.objects.create(selling=selling, **product_data)
        return selling

我收到此错误：

django.db.utils.IntegrityError: (1048, "Column 'customer_id' cannot be null")

如果我这样写：

class SellingSerializer():
    ...
    def create(self, validated_data):        
        selling = Selling.objects.create(**validated_data) #i didn't pass customer here        
        return selling

我收到此错误：

ValueError: Cannot assign "OrderedDict...
..Selling.customer must be a "Customer" instance

• 如果数据类型是 OrderedDict，我不知道如何提取或访问数据。我该怎么做呢？

我想为 Selling 和 SellingProduct、Painting 创建一条记录，我不想在每个请求中创建 Customer、Address、Product 记录，我将使用存在（在前端选择的）数据。

提前感谢大家的帮助！

Answer 1

如果您进行一些修改，您的第一种方法应该会奏效。您的销售模型依赖于客户，因此您首先需要创建一个客户。然后，您的 SellingProduct 模型依赖于产品和绘画，因此您首先需要创建一个产品和绘画，然后使用这些实例创建一个 SellingProduct，如下所示：

class SellingSerializer():
    ...
    def create(self, validated_data):
        customer_data = validated_data.pop('customer')
        selling_products_data = validated_data.pop('products')

        customer = Customer.objects.create(**customer_data)
        selling = Selling.objects.create(customer=customer, **validated_data)

        for selling_product_data in selling_products_data :
            product_data = selling_product_data.pop('product')
            product = Product.objects.create(**product_data)

            painting_data = selling_product_data.pop('painting')
            painting = Painting.objects.create(**painting_data)

            SellingProducts.objects.create(selling=selling, product=product, painting=painting)

        return selling

当然，这种方法会为每个请求创建一个新的客户、产品和绘画。这真的是你想要的吗？如果您不想为每个请求创建新的 Product 和 Painting 实例，而是使用对现有实例的引用，您可以将它们定义为 SellingSerializer 和 SellingProductSerializer 中的 PrimaryKeyRelatedField 字段。然后，您可以将您的创建功能更改为：

def create(self, validated_data):
    customer = validated_data.pop('customer')
    selling_products_data = validated_data.pop('products')

    selling = Selling.objects.create(customer=customer, **validated_data)

    for selling_product_data in selling_products_data :
        SellingProducts.objects.create(selling=selling, **selling_product_data )

    return selling

Answer 2

您需要先使用CustomerSerializer 创建客户对象和数据库行，然后才能创建带有外键的Selling 对象。您正在尝试不传递任何内容或正在传递 JSON（在您的错误消息中变成 OrderedDict）。

class SellingSerializer():
    ...
    def create(self, validated_data):
        customer_data = validated_data.pop('customer')
        products_data = validated_data.pop('products')
        customer = CustomerSerializer.save(**customer_data)
        selling = Selling.objects.create(customer=customer, **validated_data)
        for product_data in products_data:
            SellingProducts.objects.create(selling=selling, **product_data)
        return selling

也许在这个问题上重新阅读documentation。

Answer 3

1. SellingSerializer 与 CustomerSerializerh、ProductSerializer 相关

2. 在创建 Selling 对象之前，我们可以验证每个序列化器并创建

3. 更新验证数据

4. 多对多进程

您不会只是创建客户对象产品对象。必须验证数据并且可以使用 CustomerSerializer 和 ProductSerializer。在创建它们之前，使用 CustomerSerializer 和 ProductSerializer 序列化您的数据，然后是有效的创建对象，否则会引发异常。

class SellingSerializer():
    ...

    def create(self, validated_data):
        # First Let's handle Customer data
        customer_data = validated_data.pop('customer')
        customer_serializer = CustomerSerializer(data=customer_data)
        customer_serializer.is_valid(raise_exception=True)
        customer = customer_serializer.save()
        validated_data.update({'customer':customer})  ## update our validated data with customer instance

        # Create Selling object
        selling = Selling.objects.create(**validated_data)  # will receive customer instance as well

        # Handle Products related Data
        products_data = validated_data.pop('products')
        for product_data in products_data:
            product_serializer = ProductSerializer(data=product_data)
            product_serializer.is_valid(raise_exception=True)
            product = product_serializer.save()
            SellingProducts.objects.create(selling=selling, product=product)

        return selling