Question

我有以下模型。

class Sale(models.Model):
    # a sale can be made by a directSale or an Access
    directSale = models.ForeignKey('selling.DirectSale', null=True, blank=True)

    access = models.ForeignKey('access.Access', null=True, blank=True)

    product = models.ForeignKey(CustomProduct)

    price_table = models.ForeignKey('products.CustomPriceTable',   related_name='sales', null=True)

    quantity = models.PositiveIntegerField(
        'quantidade', null=False, blank=False, default=0,
    )

    discount = models.PositiveSmallIntegerField(
        'desconto', null=False, blank=False, default=0,
    )

    original_price = models.DecimalField(
    'preço original', null=False, blank=False, max_digits=10, decimal_places=2, default=0,
    )

    discount_price = models.DecimalField(
    'preço com desconto', null=False, blank=False, max_digits=10, decimal_places=2, default=0,
    )

    total = models.DecimalField(
    'Valor total', null=False, blank=False, default=0, max_digits=10, decimal_places=2
    )

    created_at = models.DateTimeField(
        'Criada em', auto_now_add=True
    )

要序列化上面的模型，我有以下序列化程序

class SaleSerializer(serializers.ModelSerializer):
    product_pv = serializers.ReadOnlyField(source='product.pv')
    product_name = serializers.ReadOnlyField(source='product.name')
    product_id = serializers.ReadOnlyField(source='product.id')
    direct_sale_date = serializers.ReadOnlyField(source='directSale.date')
    client = serializers.ReadOnlyField(source='directSale.client.name')

    def __init__(self, direct_sale, *args, **kwargs):
        self.direct_sale = direct_sale
        super(SaleSerializer, self).__init__(*args, **kwargs)

    def create(self, validated_data):
        sale = Sale(**validated_data)
        sale.directSale = self.direct_sale
        price_table = sale.directSale.account.preferences_dict['table_sale']
        sale.price_table = sale.product.price_tables.get(name=price_table)
        sale.total = sale.calculate_value()
        sale.save()
        return sale

    class Meta:
        model = Sale
        fields = (
            'id',
            'access',
            'directSale',
            'discount',
            'discount_price',
            'original_price',
            'price_table',
            'product',
            'quantity',
            'total',
            'direct_sale_date',
            'product_pv',
            'product_name',
            'product_id',
            'client',
            'created_at'
        )

为什么以下代码在字段值中返回None？

from selling.api.serializers import SaleSerializer
from selling.models import Sale

sale = Sale.objects.all()[0]
sale.quantity
1
serializer = SaleSerializer(sale)

serializer.data
ReturnDict([('access', None), ('directSale', None), ('discount', None), ('discount_price', None), ('original_price', None), ('price_table', None), ('product', None), ('quantity', None), ('total', None)])

如上所示，quantity属性的值等于1.但是在'serializer.data'中，quantity属性的值为None。

谢谢！

Answer 1

在您的SaleSerializer中，您的第一个参数为direct_sale，并且您将实例作为direct_sale的参数传递。

您应该像

一样调用它

serializer = SaleSerializer(True, sale)

或

serializer = SaleSerializer(True, instance=sale)

DRF 3.0返回无值的序列化数据。

1 个答案: