实验楼---------购物车及订单实现

1、流程

2、购物车实现

####################carapp/models.py###########################################
from django.db import models

# Create your models here.
from utils.MyBaseModel import Base


class Car(Base):
    title = models.CharField('商品名称', max_length=24)
    price = models.DecimalField('商品价格', max_digits=8, decimal_places=2)
    number = models.IntegerField('数量', default=1)
    period = models.IntegerField('有效期', default=365)
    goods = models.ForeignKey('goodsapp.Goods', on_delete=models.PROTECT, null=True)
    users = models.ForeignKey('userapp.User', on_delete=models.CASCADE, null=True)
    
##########################  carapp/serializers.py  #######################
from rest_framework import serializers

from carapp import models

class CarSer(serializers.ModelSerializer):
    class Meta:
        model = models.Car
        fields = '__all__'
        
#############################carapp/views.py#################################
from rest_framework.views import APIView
from rest_framework.response import Response
from carapp import models, serializers


class CarView(APIView):
    """
    购物车
    """
    def post(self, request):
        title = request.data.get('title')
        number = request.data.get('number')
        price = request.data.get('price')
        goods_id = request.data.get('id')
        uid = request.user.id
        print(title, number, price, goods_id, uid)
        try:
            car_obj = models.Car.objects.get(goods_id=goods_id, users_id=uid)
            car_obj.number += 1
            car_obj.save()

        except:
            car_obj = models.Car.objects.create(title=title, number=number,
                                                price=price, goods_id=goods_id, users_id=uid)
        return Response({'code': 200, 'msg': '添加成功', 'data': car_obj.id})

    def get(self, request):
        uid = request.user.id
        car_obj = models.Car.objects.filter(users_id=uid)
        ser_obj = serializers.CarSer(car_obj, many=True)
        return Response({'code': 200, 'data': ser_obj.data})

3、事务的 运用

原理

	1.事务（Transaction）是数据库区别于文件系统的重要特性之一，事务会把数据库从一种一致性状态转换为另一种一致性状态。
	2. 在数据库提交时，可以确保要么所有修改都已保存，要么所有修改都不保存。

特征

1. 原子性(Atomicity)：整个事物的所有操作要么全部提交成功，要么全部失败回滚(不会出现部分执行的情况)。
2. 一致性(Consistency)：几个并行执行的事务，其执行结果必须与按某一顺序串行执行的结果相一致。
3. 隔离性(Isolation)：事务的执行不受其他事务的干扰，事务执行的中间结果对其他事务必须是透明的。
4. 持久性(Durability):  一个事务一旦被提交了，那么对数据库中的数据的改变就是永久性的，即便是在数据库系统遇到故障的情况下也不会丢失提交事务的操作。

django中应用

from django.db import  transaction

try:
    with transaction.atomic():
        ...要执行的多个操作...
        return Response({"code": 200,"msg":"成功"})
    except IntegrityError:
        return Response({"code": 502})

4、订单实现

#####################  goodsapp/models.py  ##################
from django.db import models

# Create your models here.
from utils.MyBaseModel import Base


class Goods(Base):
	"""
	商品表
	"""
    GOODS_TYPE = (
        ('1', 'Vip'),
        ('2', 'Course')
    )
    CHANNEL_TYPE = (
        ('1', '普通'),
        ('2', '促销')
    )
    course = models.ForeignKey('courseapp.Course', on_delete=models.PROTECT)
    goods_type = models.CharField('商品种类', choices=GOODS_TYPE, max_length=8)
    product_id = models.CharField('产品id', max_length=8)
    title = models.CharField('商品名称', max_length=24)
    price = models.DecimalField('商品价格', max_digits=8, decimal_places=2)
    channel_type = models.CharField('购买渠道', choices=CHANNEL_TYPE, max_length=8)
    period = models.IntegerField('有效期', default=365)

    is_launched = models.BooleanField('是否上架', default=True)

    class Meta:
        db_table = 'tb_goods'

    def __str__(self):
        return self.title



class Orders(Base):
	"""
	订单表
	"""
    PAY_METHOD = (
        (1, "支付宝"),
    )
    ORDER_STATUS = (
        (1, "待支付"),
        (2, "已支付"),
        (3, "已取消"),
    )
    user = models.ForeignKey('userapp.User', on_delete=models.PROTECT, null=True,verbose_name="下单用户")
    order_id = models.CharField('本地订单号', max_length=256)
    trade_no = models.CharField('支付宝订单号', max_length=32, null=True)  # 28位
    pay_time = models.DateTimeField('支付时间', null=True)
    pay_method = models.CharField('支付方式', choices=PAY_METHOD, default=1, max_length=8)
    status = models.CharField('支付状态', choices=ORDER_STATUS, default=1, max_length=8)
    total_amount = models.DecimalField(max_digits=10, decimal_places=2, verbose_name="商品总金额",null=True)

    class Meta:
        db_table = 'tb_orders'

    def __str__(self):
        return self.order_id


class GoodDeatil(Base):
	""""
	订单详情表
	"""
    GOODS_TYPE = (
        ('1', 'Vip'),
        ('2', 'Course')
    )
    CHANNEL_TYPE = (
        ('1', '普通'),
        ('2', '促销')
    )
    goods = models.ForeignKey('goodsapp.Goods', on_delete=models.PROTECT,null=True)
    orders = models.ForeignKey('goodsapp.Orders', on_delete=models.PROTECT)
    number = models.IntegerField("商品数量",null=True)
    goods_type = models.CharField('商品种类', choices=GOODS_TYPE, max_length=8,default="2")
    title = models.CharField('商品名称', max_length=24)
    price = models.DecimalField('商品价格', max_digits=8, decimal_places=2)
    channel_type = models.CharField('购买渠道', choices=CHANNEL_TYPE, max_length=8,default="1")
    period = models.IntegerField('有效期', default=365)

    class Meta:
        db_table = 'tb_gooddeatil'

    def __str__(self):
        return self.title

######################  goodsapp/serializers.py   ####################
from rest_framework import serializers
from goodsapp import models as goodsmodel

class OrderSer(serializers.ModelSerializer):
    class Meta:
        model = goodsmodel.Orders
        fields = "__all__"

######################  goodsapp/views.py   ##################3##
import uuid

from django.shortcuts import render
from rest_framework.response import Response
from rest_framework.views import APIView
from carapp.models import Car
from goodsapp import models, serializers
# Create your views here.
from rest_framework.viewsets import ModelViewSet

from django.db import transaction

class OrderView(APIView):
    def post(self, request):
        uid = request.user.id
        car_list = request.data.get('id_list')
        print(car_list)
        # 查询商品信息
        car_obj = Car.objects.filter(id__in=car_list)
        total_money = 0
        try:
        	# 使用事务 确保 三个表 都操作成功
            with transaction.atomic():
                # 添加订单
                uuid_str = str(uuid.uuid4())
                order_obj = models.Orders.objects.create(order_id=uuid_str, user_id=uid)
                # 添加订单详情
                for i in car_obj:
                    order_detail_obj = models.GoodDeatil.objects.create(
                        goods=i.goods, orders=order_obj, number=i.number, title=i.title, price=i.price
                    )
                    total_money += i.price * i.number

                # 订单表  添加订单总金额
                order_obj.total_amount = total_money
                order_obj.save()
                # 删除购物车
                car_obj.delete()

                return Response({'code': 200, 'msg': '订单添加成功'})
        except:
            return Response({'code': 500, 'msg': '订单添加失败'})

    def get(self, request):
        uid = request.user.id
        order_obj = models.Orders.objects.filter(user_id=uid, status='1')
        ser_obj = serializers.OrderSer(order_obj, many=True)

        return Response({'msg': '成功', 'code': 200, 'data': ser_obj.data})