IntegrityError：“invoiceOwner_id”列中的空值违反非空约束

Question

在我的 django 应用程序中，每当我想添加一个使用表 paymentInvoice 的新对象时，我都会遇到困难。

我从我的 api 得到的错误看起来像这样

/api/clients/invoice/ 处的 IntegrityError “invoiceOwner_id”列中的空值违反非空约束 详细信息：失败行包含 (10, INV-0006, Lix, 2020-08-04, 1, Pending, 3000, null)。

注意：我还没有创建字段invoiceOwner_id，postgres 自动添加了它，或者更确切地说是使用它作为我的invoiceOwner 字段的表示

class Purchaser(models.Model):
    name = models.CharField(max_length=50)
    phone = models.CharField(max_length=20, unique=True)
    email = models.EmailField(max_length=255, unique=True, blank=True)
    image = models.ImageField(default='default.png', upload_to='customer_photos/%Y/%m/%d/')
    data_added = models.DateField(default=datetime.date.today)

    def __str__(self):
        return self.name


class paymentInvoice(models.Model):

    invoiceNo = models.CharField(max_length=50, unique=True, default=increment_invoice_number)
    invoiceOwner = models.ForeignKey(Purchaser, on_delete=models.CASCADE, related_name="invoice_detail")
    product = models.CharField(max_length=50, blank=True)
    date = models.DateField(default=datetime.date.today)
    quantity = models.PositiveSmallIntegerField(blank=True, default=1)
    payment_made = models.IntegerField(default=0)

    def __str__(self):
        return self.invoiceOwner.name

序列化程序文件

class paymentInvoiceSerializer(serializers.ModelSerializer):
    invoiceOwner = serializers.SerializerMethodField()

    class Meta:
        model = paymentInvoice
        fields = '__all__'

    def get_invoiceOwner(self, instance):
        return instance.invoiceOwner.name

视图文件

class paymentInvoiceListCreateView(ListCreateAPIView):

    serializer_class = paymentInvoiceSerializer
    queryset = paymentInvoice.objects.all().order_by('-date')

GET api 调用的结果。

{
    "id": 1,
    "invoiceOwner": "Martin",
    "invoiceNo": "INV-0001",
     "product": "",
    "date": "2020-08-04",
    "quantity": 1,
    "payment_made": 0
}

尝试以POST 的身份在下方传递，但出现主要错误

{
    "invoiceOwner": "Becky",
    "product": "Lix",
    "quantity": 1,
    "payment_made": 3000
}

Answer 1

您的 serializers.py 中的“invoiceOwner”是一个 SerializerMethodField，它是 readonly 这就是你得到错误的原因，你必须自己定义 create 方法

Answer 2

正如我在评论中所说：您需要在序列化程序中显式覆盖 create 方法，因为您的模型具有外键 invoiceOwner，只是为了首先将该实例创建为 Purchaser 实例。

你可以试试下面的代码：

class paymentInvoiceSerializer(serializers.ModelSerializer):
    invoiceOwner = serializers.SerializerMethodField()

    class Meta:
        model = paymentInvoice
        fields = '__all__'

    def get_invoiceOwner(self, instance):
        return instance.invoiceOwner.name

   def create(self, validated_data):
        purchaser_name = validated_data.get("invoiceOwner") 
        purchaser = Purchaser(name=purchaser_name,
            # you need to have phone, email, since these fields are unique,
            # they can't remain null
        )
        purchaser.save()
        return paymentInvoice.objects.create(invoiceOwner = purchaser, **validated_data)