我如何在Django Rest Framework API中包括中介模型

Question

目前，我正在學習有關Django Rest Framework的知識，偶然發現了一個棘手的部分，我似乎無法在我們的項目中工作。 我們的項目是一個虛構的網上商店，您可以在其中將愛犬嬰兒放入購物車並訂購。 我們的前端通過Django Rest Framework與后端進行通信。 我們擁有的三個主要模型是“用戶”，“訂單”和“小狗”。 因為每個訂單都有一個幼犬列表，每個幼犬都有自己的數量，所以我們需要兩者的中介模型，因為簡單的ManyToManyField顯然無法處理額外的列。 這使事情變得更加復雜（至少對於Django新手而言）。

如何在序列化器和視圖中反映關系，如何形成從前端發送的JSON對象？

也：

在哪里可以計算訂單總價？

即使我不想編輯或獲得一個特定的訂單，我也需要OrderDetail視圖嗎？或者OrderList視圖足夠嗎？

這里有一個問題正在解決類似的問題： 在Django Rest Framework的響應中包括中介（通過模型），我在代碼中實現了它，並使它現在可以工作，這要感謝Daniel Roseman的評論。 現在可以通過/ admin手動創建訂單並獲取訂單。 我仍然無法通過API創建訂單。

這是我的代碼：

models.py：

from django.db import models
from django.conf import settings
from django.contrib.auth.models import User
from django.db.models.signals import post_save
from django.dispatch import receiver


class Puppy(models.Model):
    name = models.CharField(max_length=30)
    price = models.DecimalField(max_digits=6, decimal_places=2)
    image_url = models.CharField(max_length=200)
    age = models.IntegerField(null=True)
    weight = models.IntegerField(null=True)
    description_de = models.CharField(max_length=500, null=True)
    description_en = models.CharField(max_length=500, null=True)

    def __str__(self):
        return self.name


class Order(models.Model):
    total_price = models.DecimalField(max_digits=9, decimal_places=2)
    puppies = models.ManyToManyField(Puppy, through='PuppyOrder')
    date = models.DateTimeField()
    user = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE, related_name='orders')

    def save(self, *args, **kwargs):
        """
        Create a new Order
        """
        print("An order is being saved: " + str(Order.id))
        super(Order, self).save(*args, **kwargs)

    def __str__(self):
        return str(self.id)


class PuppyOrder(models.Model):
    order = models.ForeignKey(Order, on_delete=models.CASCADE)
    puppy = models.ForeignKey(Puppy, on_delete=models.CASCADE)
    amount = models.IntegerField()

    def __str__(self):
        return self.id


class Address(models.Model):
    user = models.OneToOneField(User, on_delete=models.CASCADE)
    # Some more address fields ...


@receiver(post_save, sender=User)
def create_user_address(sender, instance, created, **kwargs):
    if created:
        Address.objects.create(user=instance)


@receiver(post_save, sender=User)
def save_user_address(sender, instance, **kwargs):
    instance.address.save()

views.py：

from rest_framework.decorators import api_view
from rest_framework.response import Response
from rest_framework.reverse import reverse
from rest_framework.exceptions import ValidationError
from rest_framework_jwt.serializers import VerifyJSONWebTokenSerializer
from .serializers import UserSerializer, UserSerializerWithToken, OrderSerializer, PuppySerializer
from .permissions import IsOwner


@api_view(['GET'])
def api_root(request, format=None):
    return Response({
        'users': reverse('user-list', request=request, format=format),
        'orders': reverse('order-list', request=request, format=format),
        'puppies': reverse('puppy-list', request=request, format=format),
    })


class OrderList(generics.ListCreateAPIView):
    http_method_names = ["get", "post"]
    queryset = Order.objects.all()
    permission_classes = (permissions.IsAuthenticatedOrReadOnly,)
    serializer_class = OrderSerializer

    def get_queryset(self):
        # Validation Code and getting self.request.user from jwt token ...
        if self.request.user.is_anonymous:
            return None
        return Order.objects.all().filter(user=self.request.user)

    def perform_create(self, serializer):
        # Validation Code and getting self.request.user from jwt token ...
        serializer.save(user=self.request.user)


class OrderDetail(generics.RetrieveUpdateDestroyAPIView):
    http_method_names = ["get", "post"]
    permission_classes = (permissions.IsAuthenticatedOrReadOnly,)
    queryset = Order.objects.all()
    serializer_class = OrderSerializer


class UserList(generics.ListAPIView):
    http_method_names = ["get", "post"]
    queryset = User.objects.all().select_related('address')
    serializer_class = UserSerializer


class UserDetail(generics.RetrieveAPIView):
    http_method_names = ["get", "post"]
    queryset = User.objects.all().select_related('address')
    serializer_class = UserSerializer


class PuppyList(generics.ListAPIView):
    http_method_names = ["get"]
    permission_classes = (permissions.AllowAny,)
    queryset = Puppy.objects.all()
    serializer_class = PuppySerializer


class PuppyDetail(generics.RetrieveAPIView):
    http_method_names = ["get"]
    permission_classes = (permissions.AllowAny,)
    queryset = Puppy.objects.all()
    serializer_class = PuppySerializer

serializers.py：

from rest_framework import serializers
from rest_framework_jwt.settings import api_settings
from django.contrib.auth.models import User
from .models import Order, Puppy, PuppyOrder


class UserSerializer(serializers.ModelSerializer):
    orders = serializers.PrimaryKeyRelatedField(many=True, read_only=True)

    class Meta:
        model = User
        fields = ('id', 'username', 'orders')


class UserSerializerWithToken(serializers.ModelSerializer):

# Neccessary code for generating a JWT token ...


class PuppySerializer(serializers.ModelSerializer):
    description = serializers.SerializerMethodField()

    def get_description(self, puppy):
        return {'DE': puppy.description_de, 'EN': puppy.description_en}

    class Meta:
        model = Puppy
        fields = ('id', 'name', 'price', 'image_url', 'age', 'weight', 'description')


class PuppyOrderSerializer(serializers.ModelSerializer):
    puppy = serializers.ReadOnlyField(source='order.puppy')
    order = serializers.ReadOnlyField(source='order.order')

    class Meta:
        model = PuppyOrder
        fields = ('id', 'puppy', 'amount')


class OrderSerializer(serializers.ModelSerializer):
    user = serializers.ReadOnlyField(source='user.username')
    puppies = PuppyOrderSerializer(source='puppyorder_set', many=True) 
    # This is currently producing an error
    # puppies = serializers.PrimaryKeyRelatedField(many=True, read_only=True)

    class Meta:
        model = Order
        fields = ('id', 'total_price', 'puppies', 'date', 'user')

隨時告訴我，您是否在我的代碼中看到某些可以改進或沒有意義的東西。 在此先感謝您，任何幫助將不勝感激！

Answer 1

通過在PuppyOrder模型中的ForeignKeys上指定related_names，您已經破壞了事情。 刪除那些。