十、购物车、订单管理和支付功能

# trade/serializer.py
__author__ = 'derek'

from .models import ShoppingCart
from rest_framework import serializers
from goods.models import Goods

class ShopCartSerializer(serializers.Serializer):
    #获取当前登录的用户
    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"
                                    })
    #这里是继承Serializer，必须指定queryset对象，如果继承ModelSerializer则不需要指定
    #goods是一个外键，可以通过这方法获取goods object中所有的值
    goods = serializers.PrimaryKeyRelatedField(required=True, queryset=Goods.objects.all())

    #继承的Serializer没有save功能，必须写一个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:self.request.user；serizlizer中: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)
        #如果购物车中有记录，数量+1
        #如果购物车车没有记录，就创建
        if existed:
            existed = existed[0]
            existed.nums += nums
            existed.save()
        else:
            #添加到购物车
            existed = ShoppingCart.objects.create(**validated_data)

        return existed

# trade/views.py

from rest_framework import viewsets
from rest_framework.permissions import IsAuthenticated
from utils.permissions import IsOwnerOrReadOnly
from rest_framework_jwt.authentication import JSONWebTokenAuthentication
from rest_framework.authentication import SessionAuthentication
from .serializers import ShopCartSerializer
from .models import ShoppingCart

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 = ShopCartSerializer

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

# 配置购物车的url
router.register(r'shopcarts', ShoppingCartViewset, base_name="shopcarts")

 def update(self, instance, validated_data):
        # 修改商品数量
        instance.nums = validated_data["nums"]
        instance.save()
        return instance

 lookup_field = "goods_id"

class ShopCartDetailSerializer(serializers.ModelSerializer):
    '''
    购物车商品详情信息
    '''
    # 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")

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

#订单中的商品
class OrderGoodsSerialzier(serializers.ModelSerializer):
    goods = GoodsSerializer(many=False)
    class Meta:
        model = OrderGoods
        fields = "__all__"

#订单商品信息
# goods字段需要嵌套一个OrderGoodsSerializer
class OrderDetailSerializer(serializers.ModelSerializer):
    goods = OrderGoodsSerialzier(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)


    def generate_order_sn(self):
        #生成订单号
        # 当前时间+userid+随机数
        from random import Random
        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__"

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)
    serializer_class = OrderSerializer
    #动态配置serializer
    def get_serializer_class(self):
        if self.action == "retrieve":
            return OrderDetailSerializer
        return OrderSerializer
    #获取订单列表
    def get_queryset(self):
        return OrderInfo.objects.filter(user=self.request.user)
    
    #在订单提交保存之前还需要多两步步骤，所以这里自定义perform_create方法
    #1.将购物车中的商品保存到OrderGoods中
    #2.清空购物车
    def perform_create(self, serializer):
        order = serializer.save()
        # 获取购物车所有商品
        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

# 配置订单的url
router.register(r'orders', OrderViewset, base_name="orders")