json - Django休息框架: Deserializing and get the primary key from validated_data

Question

我定义了一个嵌套模型Product，如下所示。每个 Product 可以属于多个 Productlist。

class Product(models.Model):
    product_id = models.AutoField(primary_key=True)
    product_name = models.CharField(max_length=50)

class Productlist(models.Model):
    productlist_id = models.AutoField(primary_key=True)
    productlist_name = models.CharField(max_length=50)
    product = models.ManyToManyField(Product, related_name='productlists')

对应的序列化器是:

class ProductlistSerializer(serializers.ModelSerializer):
    class Meta:
        model = Productlist
        fields = ('productlist_id', 'productlist_name',)

class ProductSerializer(serializers.ModelSerializer):
    productlists = ProductlistSerializer(many=True, required=False)

    class Meta:
        model = Product
        fields = ('product_id', 'product_name', 'product lists')

    def create(self, validated_data):
        #some codes

当我POST一个新的Product时(url(r'^api/products/$',views.ProductEnum.as_view() )，我想更新产品列表，以便将新产品添加到相应的产品列表中。我更喜欢使用的 JSON 文件是:

{
    "product_name": "product1"
    "productlist": [
        {
            "productlist_id": 1,
            "productlist_name": "list1",
        },
        {
            "productlist_id": 2,
            "productlist_name": list2"
        }
    ]
}

问题是我无法从 validated_data 获取 productlist_id。在 Django Rest Framework 中，您始终需要调用 to_internal_value() 来反序列化数据并生成 validated_data。经过一番调试，我检查了DRF的代码，并在to_internal_value()中找到了以下代码片段:

def to_internal_value(self, data):
    """
    Dict of native values <- Dict of primitive datatypes.
    """
    if not isinstance(data, dict):
        message = self.error_messages['invalid'].format(
            datatype=type(data).__name__
        )
        raise ValidationError({
            api_settings.NON_FIELD_ERRORS_KEY: [message]
        })

    ret = OrderedDict()
    errors = OrderedDict()
    fields = [
        field for field in self.fields.values()
        if (not field.read_only) or (field.default is not empty)
    ]

    for field in fields:
        validate_method = getattr(self, 'validate_' + field.field_name, None)
        primitive_value = field.get_value(data)
        try:
            validated_value = field.run_validation(primitive_value)
            if validate_method is not None:
                validated_value = validate_method(validated_value)
        except ValidationError as exc:
            errors[field.field_name] = exc.detail
        except DjangoValidationError as exc:
            errors[field.field_name] = list(exc.messages)
        except SkipField:
            pass
        else:
            set_value(ret, field.source_attrs, validated_value)

    if errors:
        raise ValidationError(errors)

    return ret

请注意，to_internal_value 的字段已忽略 IntegerField(read_only=True)，因为它无法满足以下条件:

        fields = [
            field for field in self.fields.values()
            if (not field.read_only) or (field.default is not empty)
        ]

因此 validated_data 将仅包含以下数据:

{
    "product_name": "product1"
    "productlist": [
        {
            "productlist_name": "list1",
        },
        {
            "productlist_name": list2"
        }
    ]
}

如何获取产品列表的主键？提前致谢!

Answer 1

经过一番挖掘，我发现 read_only 字段仅用于输出呈现。你可以在官方github上找到类似的问题link Django REST 框架。

因此解决方案是覆盖序列化器中的 read_only 字段，如下所示:

class ProductlistSerializer(serializers.ModelSerializer):
    productlist_id = serializers.IntegerField(read_only=False)

    class Meta:
        model = Productlist
        fields = ('productlist_id', 'productlist_name',)