商城项目---day09---订单模块

「爱情、让人受尽委屈。」 2022-12-06 05:27 200阅读 0赞

## 一：新建订单应用并迁移建表： ##

1：新建应用orders:

python3 ../manage.py startapp orders

2:注册子应用，配置路由：

1:dev.py
      'apps.orders',
    2:总路由
    path("",include('apps.orders.urls')),
    3：子路由：
    urlpatterns = [
        
    ]

3：创建模型类：

from meiduo_mall.utils.models import BaseModel
    from django.db import models
    
    class OrderInfo(BaseModel):
        """订单信息"""
        PAY_METHODS_ENUM = {
        
            "CASH": 1,
            "ALIPAY": 2
        }
        PAY_METHOD_CHOICES = (
            (1, "货到付款"),
            (2, "支付宝"),
        )
        ORDER_STATUS_ENUM = {
        
            "UNPAID": 1,
            "UNSEND": 2,
            "UNRECEIVED": 3,
            "UNCOMMENT": 4,
            "FINISHED": 5
        }
        ORDER_STATUS_CHOICES = (
            (1, "待支付"),
            (2, "待发货"),
            (3, "待收货"),
            (4, "待评价"),
            (5, "已完成"),
            (6, "已取消"),
        )
        order_id = models.CharField(max_length=64, primary_key=True, verbose_name="订单号")
        user = models.ForeignKey('users.User', on_delete=models.PROTECT, verbose_name="下单用户")
        address = models.ForeignKey('users.Address', on_delete=models.PROTECT, verbose_name="收货地址")
        total_count = models.IntegerField(default=1, verbose_name="商品总数")
        total_amount = models.DecimalField(max_digits=10, decimal_places=2, verbose_name="商品总金额")
        freight = models.DecimalField(max_digits=10, decimal_places=2, verbose_name="运费")
        pay_method = models.SmallIntegerField(choices=PAY_METHOD_CHOICES, default=1, verbose_name="支付方式")
        status = models.SmallIntegerField(choices=ORDER_STATUS_CHOICES, default=1, verbose_name="订单状态")
    
        class Meta:
            db_table = "tb_order_info"
            verbose_name = '订单基本信息'
            verbose_name_plural = verbose_name
    
        def __str__(self):
            return self.order_id
    
    
    class OrderGoods(BaseModel):
        """订单商品"""
        SCORE_CHOICES = (
            (0, '0分'),
            (1, '20分'),
            (2, '40分'),
            (3, '60分'),
            (4, '80分'),
            (5, '100分'),
        )
        order = models.ForeignKey(OrderInfo, related_name='skus', on_delete=models.CASCADE, verbose_name="订单")
        sku = models.ForeignKey('goods.SKU', on_delete=models.PROTECT, verbose_name="订单商品")
        count = models.IntegerField(default=1, verbose_name="数量")
        price = models.DecimalField(max_digits=10, decimal_places=2, verbose_name="单价")
        comment = models.TextField(default="", verbose_name="评价信息")
        score = models.SmallIntegerField(choices=SCORE_CHOICES, default=5, verbose_name='满意度评分')
        is_anonymous = models.BooleanField(default=False, verbose_name='是否匿名评价')
        is_commented = models.BooleanField(default=False, verbose_name='是否评价了')
    
        class Meta:
            db_table = "tb_order_goods"
            verbose_name = '订单商品'
            verbose_name_plural = verbose_name
    
        def __str__(self):
            return self.sku.name

4：迁移建表：

python3 manage.py makemigrations
    python3 manage.py migrate

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzQxNzU3_size_16_color_FFFFFF_t_70_pic_center]

## 二：新建保存订单实现： ##

1：编辑`orders/views.py`实现视图：

2：路由：

from django.urls import re_path
    from . import views
    
    urlpatterns = [
        # 保存订单
        re_path(r'^orders/commit/$', views.OrderCommitView.as_view()),
    ]

## 三：并发下单资源竞争问题： ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzQxNzU3_size_16_color_FFFFFF_t_70_pic_center 1]  
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![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzQxNzU3_size_16_color_FFFFFF_t_70_pic_center 4]

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## 四：乐观锁下单： ##

1：修改数据库的隔离级别：

*  (1)、打开mysql配置文件: `sudo vim /etc/mysql/mysql.conf.d/mysqld.cnf`
 *  (2)、在配置文件尾部追加配置项: `transaction-isolation=READ-COMMITTED`
    
     *  注意：根据我们的分析，此处的隔离级别可以设置为`READ-COMMITTED`或`READ-UNCOMMITTED`均可实现乐观锁机制，但遵循`最大化隔离强度`原则，咱们设置为`READ-COMMITTED`级别；
     *  隔离级别越高，越能够保证数据的安全性；隔离级别越低，越有可能产生错误的数据；
     *  任何解决方案没有绝对优劣，只有相对合适；
 *  (3)、重启Mysql数据库: `sudo /etc/init.d/mysql restart`

2:编辑\`apps/orders/views.py

# 保存/新建订单
    class OrderCommitView(LoginRequiredJSONMixin, View):
    
        def post(self, request):
    
            data = json.loads(request.body.decode())
            address_id = data.get('address_id')
            pay_method = data.get('pay_method')
    
            if not all([address_id, pay_method]):
                return JsonResponse({
        'code': 400, 'errmsg': '缺少参数'})
    
            try:
                Address.objects.get(pk=address_id)
            except Address.DoesNotExist as e:
                return JsonResponse({
        'code': 400, 'errmsg': '地址不存在'})
    
            if pay_method not in [OrderInfo.PAY_METHODS_ENUM['CASH'], OrderInfo.PAY_METHODS_ENUM['ALIPAY']]:
                return JsonResponse({
        'code': 400, 'errmsg': '付款方式不支持'})
    
    
            # 0、把购物车中的sku商品数据读取出来
            cart_dict = {
        } # {1: {"count": 5, "selected": True}}
            conn = get_redis_connection('carts')
            # {b"1": b"5"}
            redis_skus = conn.hgetall('carts_%d'%request.user.id)
            # [b'1']
            redis_selected = conn.smembers('selected_%d'%request.user.id)
            for sku_id,count in redis_skus.items():
                if sku_id in redis_selected:
                    cart_dict[int(sku_id)] = {
        
                        'count': int(count),
                        'selected': sku_id in redis_selected
                    }
            sku_ids = cart_dict.keys()
    
            # 数据/业务处理
            # 1、新建订单表数据OrderInfo(主)
            # 20200912111256000001 ----> 约定订单的id的格式：时间戳 + 用户id(固定长度)
            # 加上时间戳可以保证这个订单的id唯一性
            order_id = timezone.localtime().strftime('%Y%m%d%H%M%S') + '%06d'%request.user.id
            freight = Decimal('10.5')
    
    
            with transaction.atomic():
                # 设置一个事务保存点
                save_id = transaction.savepoint()
    
                order = OrderInfo.objects.create(
                    order_id=order_id,
                    user=request.user,
                    address_id=address_id,
                    total_count=0, # 初始化
                    total_amount=0, # 初始化
                    freight=freight,
                    pay_method=pay_method
                )
    
                # 2、插入订单商品表数据OrderGoods(从) --> 具体的sku商品就是购物车中选中的商品
                for sku_id in sku_ids:
    
                    # 乐观锁处理机制
                    while True:
                        # 购物车中的sku商品
                        sku = SKU.objects.get(pk=sku_id)
                        # (1)、读旧的库存和销量
                        old_stock = sku.stock
                        old_sales = sku.sales
    
                        # TODO: 判断库存和销量
                        # 用户下单量
                        count = cart_dict[sku_id]['count']
                        if count > old_stock:
                            # 库存不足, 回滚事务
                            transaction.savepoint_rollback(save_id)
                            return JsonResponse({
        'code': 400, 'errmsg': '库存不足'}, status=400)
    
                        # 修改销量和库存数据
                        # sku.stock -= count
                        # sku.sales += count
                        # sku.save()
    
                        # (2)、基于旧库存和销量计算新值
                        new_stock = old_stock - count
                        new_sales = old_sales + count
                        # (3)、在旧库存和销量基础上，查询后修改
                        ret = SKU.objects.filter(
                            pk=sku.id,
                            stock=old_stock,
                            sales=old_sales
                        ).update(stock=new_stock, sales=new_sales)
                        # 如果update函数返回值为0，说明filter过滤结果为空，说明根据旧数据找不到原有的sku
                        # 说明有别的事务介入
                        if ret:
                            # 如果ret不为0，说明正确更新
                            break
    
                    # 中间表OrderGoods表中插入一条数据，表示新建的订单中的sku商品
                    OrderGoods.objects.create(
                        order=order,
                        sku=sku,
                        count=cart_dict[sku_id]['count'],
                        price=sku.price,
                    )
    
                    order.total_count += cart_dict[sku_id]['count']
                    order.total_amount += cart_dict[sku_id]['count'] * sku.price
    
                order.total_amount += freight
                order.save()
    
                # 提交保存点（删除保存点）
                transaction.savepoint_commit(save_id)
    
    
            # 下单结束删除购物车
            conn.hdel('carts_%d'%request.user.id, *sku_ids)
            conn.srem('selected_%d'%request.user.id, *sku_ids)
    
            return JsonResponse({
        
                'code': 0,
                'errmsg': 'ok',
                'order_id': order_id
            })

## 五：结算页面： ##

1：`编辑apps/orders/views.py`

class OrderSettlementView(LoginRequiredJSONMixin, View):
    
        def get(self, request):
            user = request.user
    
            # 返回用户可选地址
            addresses = []
            add_queryset = Address.objects.filter(
                user=user,
                is_deleted=False
            )
            for address in add_queryset:
                addresses.append({
        
                    'id': address.id,
                    'province': address.province.name,
                    'city': address.city.name,
                    'district': address.district.name,
                    'place': address.place,
                    'mobile': address.mobile,
                    'receiver': address.receiver
                })
    
            # 返回选中的购物车数据
            skus = []
    
            conn = get_redis_connection('carts')
            # redis_skus = {b'1': b'5'}
            redis_skus = conn.hgetall('carts_%d'%user.id)
            # redis_selected = [b'1']
            redis_selected = conn.smembers('selected_%d'%user.id)
    
            for sku_id,count in redis_skus.items():
                # sku_id: b'1'; count: b'5'
                if sku_id in redis_selected:
                    sku = SKU.objects.get(pk=int(sku_id))
                    skus.append({
        
                        'id': sku.id,
                        'name': sku.name,
                        'default_image_url': sku.default_image.url,
                        'count': int(count),
                        'price': sku.price
                    })
    
            return JsonResponse({
        
                'code': 0,
                'errmsg': 'ok',
                'context': {
        
                    'addresses': addresses,
                    'skus': skus,
                    'freight': Decimal('10.5') # 计算的时候不会丢失精度
                }
            })

路由配置：

from django.urls import re_path
    from . import views
    
    urlpatterns = [
        re_path(r'^orders/settlement/$', views.OrderSettlementView.as_view()),
    ]

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