（项目）生鲜超市（九）

十、购物车，订单管理和支付功能

1、购物车功能

　　在trade/serializers.py中编写购物车序列化的代码：

class ShopCartSerialzier(serializers.Serializer):
    user = serializers.HiddenField(
        default=serializers.CurrentUserDefault()
    )
    nums = serializers.IntegerField(required=True, label='数量', min_value=1,
                                    error_messages={
                                        "min_value": "商品数量不能小于一",
                                        "required": "请选择购买数量"
                                    })
    # goods是一个外键，可以通过这方法获取goods object中所有的值 Serializer必须指定queryset对象，ModelSerializer不需要指定
    goods = serializers.PrimaryKeyRelatedField(required=True, queryset=Goods.objects.all())

    # Serializer没有save方法，必须重写create方法
    def create(self, validated_data):  # validated_data是已经处理过的数据
        # 获取当前用户，view中获取用户self.request.user serializer中获取用户self.context["request"].user
        user = self.context["request"].user
        nums = validated_data["nums"]
        goods = validated_data["goods"]

        existed = ShoppingCart.objects.filter(user=user, goods=goods)
        # 购物车有记录，数量+nums
        if existed:
            existed = existed[0]
            existed.nums += nums
            existed.save()
        else:
            # 没有记录，添加到购物车
            existed = ShoppingCart.objects.create(**validated_data)

        return existed

    # Serializer没有update方法，所以重写Update方法， 添加购物车数量
    def update(self, instance, validated_data):
        # 修改商品数量
        instance.nums = validated_data["nums"]
        instance.save()
        return instance

　　在trade/views.py中编写购物车接口：

class ShoppingCartViewSet(viewsets.ModelViewSet):
    """
    购物车功能
    list:
        获取购物车详情
    create：
        加入购物车
    delete：
        删除购物记录
    """

    permission_classes = (IsAuthenticated, IsOwnerOrReadOnly)
    authentication_classes = (JSONWebTokenAuthentication, SessionAuthentication)
    serializer_class = ShopCartSerialzier

    # 把商品id传回去
    lookup_field = 'goods_id'

    def get_queryset(self):
        return ShoppingCart.objects.filter(user=self.request.user)

　　注册url：

router.register(r'shopcarts', ShoppingCartViewSet, base_name='shopcarts')  # 购物车

　　购物车中可以看商品详情，需要写一个商品详情的serializer，在view中需要动态设置serializer：

class ShopCartDetailSerializer(serializers.ModelSerializer):
    # 一个购物车对应一个商品
    goods = GoodsSerializer(many=False, read_only=True)
    class Meta:
        model = ShoppingCart
        fields = ('goods', 'nums')

　　完善购物车接口，动态选择serializer：

class ShoppingCartViewSet(viewsets.ModelViewSet):
    """
    购物车功能
    list:
        获取购物车详情
    create：
        加入购物车
    delete：
        删除购物记录
    """

    permission_classes = (IsAuthenticated, IsOwnerOrReadOnly)
    authentication_classes = (JSONWebTokenAuthentication, SessionAuthentication)

    # 把商品id传回去
    lookup_field = 'goods_id'

    def get_serializer_class(self):
        if self.action == 'list':
            return ShopCartDetailSerializer
        else:
            return ShopCartSerializer

    def get_queryset(self):
        return ShoppingCart.objects.filter(user=self.request.user)

2、订单功能

　　用户添加商品到购物车，点击购物车结算，填上地址留言，结算生成订单，在会员中心我的订单里面，可以看到订单列表，点订单可以看到订单的详细信息，首先完成订单的序列化：

class OrderGoodsSerializer(serializers.ModelSerializer):
    # 订单内的商品
    goods = GoodsSerializer(many=False)

    class Meta:
        model = OrderGoods
        fields = "__all__"


class OrderDetailSerializer(serializers.ModelSerializer):
    # goods字段需要嵌套一个OrderGoodsSerializer
    goods = OrderGoodsSerializer(many=True)

    class Meta:
        model = OrderInfo
        fields = "__all__"


class OrderSerializer(serializers.ModelSerializer):
    user = serializers.HiddenField(
        default=serializers.CurrentUserDefault()
    )
    # 生成订单的时候这些不用post
    pay_status = serializers.CharField(read_only=True)
    trade_no = serializers.CharField(read_only=True)
    order_sn = serializers.CharField(read_only=True)
    pay_time = serializers.DateTimeField(read_only=True)
    nonce_str = serializers.CharField(read_only=True)
    pay_type = serializers.CharField(read_only=True)

    # 生成订单号
    def generate_order_sn(self):
        # 格式：当前时间+userid+随机数
        random_ins = Random()
        order_sn = '{time_str}{userid}{ranstr}'.format(time_str=time.strftime("%Y%m%d%H%M%S"),
                                                       userid=self.context["request"].user.id,
                                                       ranstr=random_ins.randint(10, 99))
        return order_sn

    def validate(self, attrs):
        # validate中添加order_sn，然后在view中就可以save
        attrs['order_sn'] = self.generate_order_sn()
        return attrs

    class Meta:
        model = OrderInfo
        fields = "__all__"

　　在views.py中完成订单的接口：

class OrderViewSet(mixins.ListModelMixin, mixins.RetrieveModelMixin, mixins.CreateModelMixin, mixins.DestroyModelMixin,
                   viewsets.GenericViewSet):
    """
    订单管理
    list:
        获取个人订单
    delete:
        删除订单
    create：
        新增订单
    """

    permission_classes = (IsAuthenticated, IsOwnerOrReadOnly)
    authentication_classes = (JSONWebTokenAuthentication, SessionAuthentication)

    def get_serializer_class(self):
        if self.action == "retrieve":
            return OrderDetailSerializer
        return OrderSerializer

    def get_queryset(self):
        return OrderInfo.objects.filter(user=self.request.user)

    # 在提交订单还需要将购物车中的商品保存到OrderGoods中，然后清空购物车
    def perform_create(self, serializer):
        order = serializer.save()

        # 获取购物车中的所有商品，将商品添加到订单中
        shop_carts = ShoppingCart.objects.filter(user=self.request.user)
        for shop_cart in shop_carts:
            order_goods = OrderGoods()
            order_goods.goods = shop_cart.goods
            order_goods.goods_num = shop_cart.nums
            order_goods.order = order
            order_goods.save()

            # 清空购物车
            shop_cart.delete()

        return order

　　注册url：

router.register(r'orders', OrderViewSet, base_name='orders')  # 订单

　　不要忘了修改Vue中的host，然后在前端测试添加商品到购物车，然后点击结算生成订单，在个人中心新中有订单信息。