在 DRF 中，我如何序列化相关模型（OneToOne）并显示数据而不是列表数据类型，而是单值实例？

Question

下面给出了代码以及当前输出和预期输出。 在 ProductPriceMapping 表中，ProductDetail 表和 PriceList 与 OneToOne 关系相关，但是当使用 related_name 参数获取价格数据时，一种产品必须有一个值，数据正在显示是 list 数据类型。

模型.py

from django.db import models

class PriceList(models.Model):
    priceCode = models.BigAutoField(primary_key= True)
    maxRetailPrice= models.FloatField(max_length=20)
    baseDiscount = models.FloatField(max_length=20, default=0)
    seasonalDiscount = models.FloatField(max_length=20, default=0)

    def __str__(self):
        return '%s'% (self.maxRetailPrice)

class ProductDetail(models.Model):
    productCode = models.BigAutoField(primary_key=True)
    productName = models.CharField(max_length=100)
    manufacturer = models.CharField(max_length=100)

    def __str__(self):
        return self.productName

class ProductPriceMapping(models.Model):
    productPriceCode= models.BigAutoField(primary_key=True)
    productCode= models.ForeignKey(ProductDetail,on_delete=models.CASCADE,related_name='price')
    priceCode= models.OneToOneField(PriceList,on_delete=models.CASCADE)

    def __str__(self):
        return '%s' % (self.priceCode)

序列化器.py

from rest_framework import serializers
from .models import CategoryDetail, EmployeeDetail, ProductCategoryMapping, ProductPriceMapping, SalaryDetail, ProductDetail, PriceList

class ProductPriceListSerializer(serializers.ModelSerializer):
    class Meta:
        model = PriceList
        fields = ('priceCode','maxRetailPrice',
                  'baseDiscount', 'seasonalDiscount')

class ProductPriceMappingSerializer(serializers.ModelSerializer):
    class Meta:
        model= ProductPriceMapping
        fields= ('productPriceCode','productCode', 'priceCode')

class ProductDetailsSerializer(serializers.ModelSerializer):
    category= serializers.StringRelatedField(many= True, read_only= True)
    price = serializers.StringRelatedField( many= True, read_only= True)
    class Meta:
        model = ProductDetail
        fields = ('productCode', 'productName', 'manufacturer','category', 'price')

API 的结果如下所示：

[
    {
        "productCode": 1,
        "productName": "NeoChef",
        "manufacturer": "LG",
        "category": [
            "1: Microwave Oven"
        ],
        "price": [
            "26000.0"  ##expected the price value not be in a list
        ]
    },
    {
        "productCode": 2,
        "productName": "The Frame",
        "manufacturer": "Samsung",
        "category": [
            "2: Television"
        ],
        "price": [
            "120000.0" ##expected the price value not be in a list
        ]
    },
    {
        "productCode": 3,
        "productName": "Galaxy S22+",
        "manufacturer": "Samsung",
        "category": [
            "3: Smart Phone"
        ],
        "price": [
            "79000.0" ##expected the price value not be in a list
        ]
    }
]

预期结果：

[
    {
        "productCode": 1,
        "productName": "NeoChef",
        "manufacturer": "LG",
        "category": [
            "1: Microwave Oven"
        ],
        "price": "26000.0"  
    }
]```

Answer 1

在您的情况下，price 字段不是一对一的相关字段，您需要将 productCode 更改为 OneToOneField 或者如果您不想更改 DB 字段，则可以实现只需使用SerializerMethodField 即可获得相同的结果。在第一种情况下，从序列化程序字段中删除 many=True 参数应该会有所帮助。在第二种情况下，SerializerMethodField 将帮助您进行自定义表示，例如：

class ProductDetailsSerializer(serializers.ModelSerializer):
    category= serializers.StringRelatedField(many=True, read_only=True)
    price = serializers.SerializerMethodField()

    class Meta:
        model = ProductDetail
        fields = ('productCode', 'productName', 'manufacturer','category', 'price')

    def get_price(self, obj):
        # If it's guaranteed that there will be only one related object, or retrieve the needed object depending on your demands
        return str(obj.price.first())

Answer 2

一种简单的方法是使用MethodField...

class ProductPriceMappingSerializer(serializers.ModelSerializer):
    priceCode = serializers.SerializerMethodField()

    class Meta:
        model= ProductPriceMapping
        fields= ('productPriceCode','productCode', 'priceCode')
    
    @staticmethod
    def get_priceCode(obj):
        return obj.priceCode.maxRetailPrice  # or any other fields that you like to show in your response

但是如果你想显示基于你的其他序列化器的所有 priceList 字段，你可以这样做：

class ProductPriceMappingSerializer(serializers.ModelSerializer):
    priceCode = ProductPriceListSerializer()

    class Meta:
        model= ProductPriceMapping
        fields= ('productPriceCode','productCode', 'priceCode')

Answer 3

谢谢各位，我是这样解决的：

模型.py

class ProductPriceMapping(models.Model):
    productPriceCode= models.BigAutoField(primary_key=True)
    productCode= models.OneToOneField(ProductDetail,on_delete=models.CASCADE,related_name='price')
    priceCode= models.ForeignKey(PriceList,on_delete=models.CASCADE)

    def __str__(self):
        return '%s' % (self.priceCode)

序列化程序.py

class ProductDetailsSerializer(serializers.ModelSerializer):
    category= serializers.StringRelatedField(many= True, read_only= True)
    price = serializers.StringRelatedField(read_only= True)
    class Meta:
        model = ProductDetail
        fields = ('productCode', 'productName', 'manufacturer','category', 'price')