郑州网站建设哪家公司好,做网站交接什么时需要交接,中国采购网招标公告,做推广哪个网站最好DRF的ModelSerializer序列化器与Django的Model模型紧密映射#xff0c;本文将通过简单的示例介绍几种处理关联关系的方法。
1. 创建模型和初始数据
创建模型
from django.db import modelsclass Product(models.Model):product_name models.CharField(max_length255)quant…DRF的ModelSerializer序列化器与Django的Model模型紧密映射本文将通过简单的示例介绍几种处理关联关系的方法。
1. 创建模型和初始数据
创建模型
from django.db import modelsclass Product(models.Model):product_name models.CharField(max_length255)quantity models.IntegerField()class Component(models.Model):product models.ForeignKey(Product, on_deletemodels.CASCADE, related_namecomponents)component_name models.CharField(max_length255)code models.CharField(max_length255)quantity models.IntegerField()class Meta:ordering [product]def __str__(self):return f{self.code}-{self.component_name}创建数据 from api.models import Product, Componentp1 Product.objects.create(product_name盖子, quantity30)Component.objects.create(productp1, component_name纤维板, codeXYB, quantity5)Component.objects.create(productp1, component_name螺丝, codeLS, quantity10)Component.objects.create(productp1, component_name密封条, codeMFT, quantity20)2. 字符串关系字段
使用StringRelatedField
from rest_framework import serializers
from .models import Productclass ProductSerializer(serializers.ModelSerializer):components serializers.StringRelatedField(manyTrue)class Meta:model Productfields [product_name, quantity, components]执行查询和序列化 from api.models import Productp1 Product.objects.prefetch_related(components).get(pk1)from api.serializers import ProductSerializerps ProductSerializer(p1)ps.data
# {product_name: 盖子, quantity: 30, components: [XYB-纤维板, LS-螺丝, MFT-密封条]}效果如下:
{product_name: 盖子, quantity: 30, components: [XYB-纤维板, LS-螺丝, MFT-密封条]
}注意观察获取查询集的代码:Product.objects.prefetch_related(components).get(pk1)不难发现我们使用了prefetch_related来获取查询集如果一次查询大量的Product不使用prefetch_related将会导致严重的性能问题N1问题。DRF的序列化器不会为你自动优化。当然我们的示例中影响不大因为只获取了一个查询集。
3. 主键关系字段
使用PrimaryKeyRelatedField
from rest_framework import serializers
from .models import Productclass ProductSerializer(serializers.ModelSerializer):components serializers.PrimaryKeyRelatedField(manyTrue, read_onlyTrue)class Meta:model Productfields [product_name, quantity, components]效果如下
{product_name: 盖子, quantity: 30, components: [1, 2, 3]
}4. 指定关系字段
使用SlugRelatedField可以指定字段来表示关联关系
from rest_framework import serializers
from .models import Productclass ProductSerializer(serializers.ModelSerializer):components serializers.SlugRelatedField(manyTrue,read_onlyTrue,slug_fieldcode)class Meta:model Productfields [product_name, quantity, components]效果如下
{product_name: 盖子, quantity: 30, components: [XYB, LS, MFT]
}5. 嵌套序列化器
from rest_framework import serializers
from .models import Product, Componentclass ComponentSerializer(serializers.ModelSerializer):class Meta:model Componentfields [component_name, code, quantity]class ProductSerializer(serializers.ModelSerializer):components ComponentSerializer(manyTrue, read_onlyTrue)class Meta:model Productfields [product_name, quantity, components]
效果如下
{product_name: 盖子,quantity: 30,components: [{component_name: 纤维板,code: XYB,quantity: 5},{component_name: 螺丝,code: LS,quantity: 10},{component_name: 密封条,code: MFT,quantity: 20}]
}6. 可写嵌套
默认上面创建的嵌套序列化器是只读的可写嵌套需要实现update、create两者或其一
from rest_framework import serializers
from .models import Product, Componentclass ComponentSerializer(serializers.ModelSerializer):class Meta:model Componentfields [component_name, code, quantity]class ProductSerializer(serializers.ModelSerializer):components ComponentSerializer(manyTrue)class Meta:model Productfields [product_name, quantity, components]def create(self, validated_data):components_data validated_data.pop(components)product Product.objects.create(**validated_data)for component_data in components_data:Component.objects.create(productproduct, **component_data)return product
可以使用此序列化器创建实例 data {product_name: 电机,quantity: 1,components: [{component_name: 铝型材,code: LXC,quantity: 5},{component_name: 螺栓,code: LSHUN,quantity: 10},]
}from api.serializers import ProductSerializers ProductSerializer(datadata)s.is_valid()
# Trues.save()
# Product: Product object (2)7. 总结注意事项
关联关系注意使用prefetch_related获取查询集。可写嵌套序列化器必须自己实现create方法update方法两者或其一。
