Django REST framework+Vue 打造生鲜超市（十二）

十三、首页、商品数量、缓存和限速功能开发

13.1.轮播图接口实现

首先把pycharm环境改成本地的，vue中local_host也改成本地

（1）goods/serializer

class BannerSerializer(serializers.ModelSerializer):
    '''
    轮播图
    '''
    class Meta:
        model = Banner
        fields = "__all__"

（2）goods/views.py

class BannerViewset(mixins.ListModelMixin, viewsets.GenericViewSet):
    """
    首页轮播图
    """
    queryset = Banner.objects.all().order_by("index")
    serializer_class = BannerSerializer

（3）url

# 配置首页轮播图的url
router.register(r'banners', BannerViewset, base_name="banners")

在后台添加首页轮播图图片

13.2.新品接口功能开发

在设计Goods model时候有一个字段is_new

is_new = models.BooleanField("是否新品",default=False)

实现这个接口只要在goods/filters/GoodsFilter里面添加一个过滤就可以了

    class Meta:
        model = Goods
        fields = ['pricemin', 'pricemax','is_hot','is_new']

在后台设置几个商品 is_new

13.3.首页商品分类显示功能

首先是大类，然后里面有

• 商品商标（多个）
• 大类下的二级类
• 广告商品
• 所有商品
  

（1）goods/serializers.py

class BrandSerializer(serializers.ModelSerializer):
    '''
    大类下面的宣传商标
    '''
    class Meta:
        model = GoodsCategoryBrand
        fields = "__all__"


class IndexCategorySerializer(serializers.ModelSerializer):
    #某个大类的商标，可以有多个商标，一对多的关系
    brands = BrandSerializer(many=True)
    # good有一个外键category，但这个外键指向的是三级类，直接反向通过外键category（三级类），取某个大类下面的商品是取不出来的
    goods = serializers.SerializerMethodField()
    # 在parent_category字段中定义的related_name="sub_cat"
    # 取二级商品分类
    sub_cat = CategorySerializer2(many=True)
    # 广告商品
    ad_goods = serializers.SerializerMethodField()

    def get_ad_goods(self, obj):
        goods_json = {}
        ad_goods = IndexAd.objects.filter(category_id=obj.id, )
        if ad_goods:
            #取到这个商品Queryset[0]
            good_ins = ad_goods[0].goods
            #在serializer里面调用serializer的话，就要添加一个参数context（上下文request）,嵌套serializer必须加
            # serializer返回的时候一定要加 “.data” ，这样才是json数据
            goods_json = GoodsSerializer(good_ins, many=False, context={'request': self.context['request']}).data
        return goods_json

    #自定义获取方法
    def get_goods(self, obj):
        # 将这个商品相关父类子类等都可以进行匹配
        all_goods = Goods.objects.filter(Q(category_id=obj.id) | Q(category__parent_category_id=obj.id) | Q(
            category__parent_category__parent_category_id=obj.id))
        goods_serializer = GoodsSerializer(all_goods, many=True, context={'request': self.context['request']})
        return goods_serializer.data

    class Meta:
        model = GoodsCategory
        fields = "__all__"

（2）goods/views.py

class IndexCategoryViewset(mixins.ListModelMixin, viewsets.GenericViewSet):
    """
    首页商品分类数据
    """
    # 获取is_tab=True（导航栏）里面的分类下的商品数据
    queryset = GoodsCategory.objects.filter(is_tab=True, name__in=["生鲜食品", "酒水饮料"])
    serializer_class = IndexCategorySerializer

（3）url

# 首页系列商品展示url
router.register(r'indexgoods', IndexCategoryViewset, base_name="indexgoods")

13.4.商品点击数和收藏数

（1）点击数

GoodsListViewSet其中继承了mixins.RetrieveModelMixin（获取商品详情）

源码

class RetrieveModelMixin(object):
    """
    Retrieve a model instance.
    """
    def retrieve(self, request, *args, **kwargs):
        instance = self.get_object()
        serializer = self.get_serializer(instance)
        return Response(serializer.data)

我们只要重写他的retrieve方法就可以了

goods/views

　　#商品点击数 + 1
    def retrieve(self, request, *args, **kwargs):
        instance = self.get_object()
        instance.click_num += 1
        instance.save()
        serializer = self.get_serializer(instance)
        return Response(serializer.data)

class GoodsListViewSet(mixins.ListModelMixin, mixins.RetrieveModelMixin,viewsets.GenericViewSet):
    '''
    list:
        商品列表，分页，搜索，过滤，排序
    retrieve:
        获取商品详情
    '''

    # authentication_classes = (TokenAuthentication,)
    #这里必须要定义一个默认的排序,否则会报错
    queryset = Goods.objects.all().order_by('id')
    # 分页
    pagination_class = GoodsPagination
    #序列化
    serializer_class = GoodsSerializer
    filter_backends = (DjangoFilterBackend,filters.SearchFilter,filters.OrderingFilter)

    # 设置filter的类为我们自定义的类
    #过滤
    filter_class = GoodsFilter
    #搜索
    search_fields = ('name', 'goods_brief', 'goods_desc')
    #排序
    ordering_fields = ('sold_num', 'shop_price')

    #商品点击数 + 1
    def retrieve(self, request, *args, **kwargs):
        instance = self.get_object()
        instance.click_num += 1
        instance.save()
        serializer = self.get_serializer(instance)
        return Response(serializer.data)

（2）收藏数

前面已经写了UserFavViewset，其中继承了mixins.CreateModelMixin,添加收藏实际就是创建数据库

这里重写它的perform_create方法就可以了

user_operation/view.py

# 用户收藏的商品数量+1
    def perform_create(self, serializer):
        instance = serializer.save()
        # 这里instance相当于UserFav model，通过它找到goods
        goods = instance.goods
        goods.fav_num += 1
        goods.save()

class UserFavViewset(viewsets.GenericViewSet, mixins.ListModelMixin, mixins.CreateModelMixin, mixins.DestroyModelMixin):
    '''
    用户收藏
    '''
    #permission是用来做权限判断的
    # IsAuthenticated：必须登录用户；IsOwnerOrReadOnly：必须是当前登录的用户
    permission_classes = (IsAuthenticated,IsOwnerOrReadOnly)
    #auth使用来做用户认证的
    authentication_classes = (JSONWebTokenAuthentication,SessionAuthentication)
    #搜索的字段
    lookup_field = 'goods_id'

    #动态选择serializer
    def get_serializer_class(self):
        if self.action == "list":
            return UserFavDetailSerializer
        elif self.action == "create":
            return UserFavSerializer
        return UserFavSerializer

    def get_queryset(self):
        #只能查看当前登录用户的收藏，不会获取所有用户的收藏
        return UserFav.objects.filter(user=self.request.user)

    # 用户收藏的商品数量+1
    def perform_create(self, serializer):
        instance = serializer.save()
        # 这里instance相当于UserFav model，通过它找到goods
        goods = instance.goods
        goods.fav_num += 1
        goods.save()

（3）用信号量实现

delete和create的时候django model都会发送一个信号量出来，用信号量的方式代码分离性更好

收藏数+1和-1

（1）user_operation/signal.py

# users_operation/signals.py

from django.db.models.signals import post_save,post_delete
from django.dispatch import receiver
from user_operation.models import UserFav

# post_save:接收信号的方式
#sender: 接收信号的model
@receiver(post_save, sender=UserFav)
def create_UserFav(sender, instance=None, created=False, **kwargs):
    # 是否新建，因为update的时候也会进行post_save
    if created:
        goods = instance.goods
        goods.fav_num += 1
        goods.save()

@receiver(post_delete, sender=UserFav)
def delete_UserFav(sender, instance=None, created=False, **kwargs):
        goods = instance.goods
        goods.fav_num -= 1
        goods.save()

（2）user_operation/apps.py

from django.apps import AppConfig
   
class UserOperationConfig(AppConfig):
    name = 'user_operation'
    verbose_name = "操作管理"

    def ready(self):
        import user_operation.signals

13.5.商品库存和销量修改

库存数量

商品库存数量的行为：

• 新增商品到购物车
• 修改购物车数量
• 删除购物车记录

trade/views.py

# 库存数-1
    def perform_create(self, serializer):
        shop_cart = serializer.save()
        goods = shop_cart.goods
        goods.goods_num -= shop_cart.nums
        goods.save()

    # 库存数+1
    def perform_destroy(self, instance):
        goods = instance.goods
        goods.goods_num += instance.nums
        goods.save()
        instance.delete()

    # 更新库存,修改可能是增加页可能是减少
    def perform_update(self, serializer):
        #首先获取修改之前的库存数量
        existed_record = ShoppingCart.objects.get(id=serializer.instance.id)
        existed_nums = existed_record.nums
        # 先保存之前的数据existed_nums
        saved_record = serializer.save()
        #变化的数量
        nums = saved_record.nums-existed_nums
        goods = saved_record.goods
        goods.goods_num -= nums
        goods.save()

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
    #商品的id
    lookup_field = "goods_id"

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

    #获取购物车列表
    def get_queryset(self):
        return ShoppingCart.objects.filter(user=self.request.user)

    # 库存数-1
    def perform_create(self, serializer):
        shop_cart = serializer.save()
        goods = shop_cart.goods
        goods.goods_num -= shop_cart.nums
        goods.save()

    # 库存数+1
    def perform_destroy(self, instance):
        goods = instance.goods
        goods.goods_num += instance.nums
        goods.save()
        instance.delete()

    # 更新库存,修改可能是增加页可能是减少
    def perform_update(self, serializer):
        #首先获取修改之前的库存数量
        existed_record = ShoppingCart.objects.get(id=serializer.instance.id)
        existed_nums = existed_record.nums
        # 先保存之前的数据existed_nums
        saved_record = serializer.save()
        #变化的数量
        nums = saved_record.nums-existed_nums
        goods = saved_record.goods
        goods.goods_num -= nums
        goods.save()

商品销量

商品的销量只有在支付成功后才会 +1

trade/views.py

                for order_good in order_goods:
                    goods = order_good.goods
                    goods.sold_num += order_good.goods_num
                    goods.save()


class AlipayView(APIView):
    def get(self, request):
        """
        处理支付宝的return_url返回
        """
        processed_dict = {}
        # 1. 获取GET中参数
        for key, value in request.GET.items():
            processed_dict[key] = value
        # 2. 取出sign
        sign = processed_dict.pop("sign", None)

        # 3. 生成ALipay对象
        alipay = AliPay(
            appid="2016091500517456",
            app_notify_url="http://47.93.198.159:8000/alipay/return/",
            app_private_key_path=private_key_path,
            alipay_public_key_path=ali_pub_key_path,  # 支付宝的公钥，验证支付宝回传消息使用，不是你自己的公钥,
            debug=True,  # 默认False,
            return_url="http://47.93.198.159:8000/alipay/return/"
        )

        verify_re = alipay.verify(processed_dict, sign)

        # 这里可以不做操作。因为不管发不发return url。notify url都会修改订单状态。
        if verify_re is True:
            order_sn = processed_dict.get('out_trade_no', None)
            trade_no = processed_dict.get('trade_no', None)
            trade_status = processed_dict.get('trade_status', None)

            existed_orders = OrderInfo.objects.filter(order_sn=order_sn)
            for existed_order in existed_orders:
                existed_order.pay_status = trade_status
                existed_order.trade_no = trade_no
                existed_order.pay_time = datetime.now()
                existed_order.save()

            response = redirect("/index/#/app/home/member/order")
            return response

        else:
            response = redirect("index")
            return response

    def post(self, request):
        """
        处理支付宝的notify_url
        """
        #存放post里面所有的数据
        processed_dict = {}
        #取出post里面的数据
        for key, value in request.POST.items():
            processed_dict[key] = value
        #把signpop掉，文档有说明
        sign = processed_dict.pop("sign", None)

        #生成一个Alipay对象
        alipay = AliPay(
            appid="2016091500517456",
            app_notify_url="http://47.93.198.159:8000/alipay/return/",
            app_private_key_path=private_key_path,
            alipay_public_key_path=ali_pub_key_path,  # 支付宝的公钥，验证支付宝回传消息使用，不是你自己的公钥,
            debug=True,  # 默认False,
            return_url="http://47.93.198.159:8000/alipay/return/"
        )

        #进行验证
        verify_re = alipay.verify(processed_dict, sign)

        # 如果验签成功
        if verify_re is True:
            #商户网站唯一订单号
            order_sn = processed_dict.get('out_trade_no', None)
            #支付宝系统交易流水号
            trade_no = processed_dict.get('trade_no', None)
            #交易状态
            trade_status = processed_dict.get('trade_status', None)

            # 查询数据库中订单记录
            existed_orders = OrderInfo.objects.filter(order_sn=order_sn)
            for existed_order in existed_orders:
                # 订单商品项
                order_goods = existed_order.goods.all()
                # 商品销量增加订单中数值
                for order_good in order_goods:
                    goods = order_good.goods
                    goods.sold_num += order_good.goods_num
                    goods.save()

                # 更新订单状态
                existed_order.pay_status = trade_status
                existed_order.trade_no = trade_no
                existed_order.pay_time = datetime.now()
                existed_order.save()
            #需要返回一个'success'给支付宝，如果不返回，支付宝会一直发送订单支付成功的消息
            return Response("success")

13.6.drf的缓存设置

为了加速网站的访问速度，将一些数据放到缓存当中，取数据的时候首先去缓存中去，然后再去数据库中取

我们用drf的一个扩展来实现缓存，github上面的使用说明：http://chibisov.github.io/drf-extensions/docs/#caching

（1）安装

pip install drf-extensions

（2）使用方法

导入

from rest_framework_extensions.cache.mixins import CacheResponseMixin

在GoodsListViewSet中添加缓存功能

#CacheResponseMixin一定要放在第一个位置

class GoodsListViewSet(CacheResponseMixin,mixins.ListModelMixin, mixins.RetrieveModelMixin,viewsets.GenericViewSet):

设置过期时间，settings里面

#缓存配置
REST_FRAMEWORK_EXTENSIONS = {
    'DEFAULT_CACHE_RESPONSE_TIMEOUT': 5   #5s过期，时间自己可以随便设定
}

这个缓存使用的是内存，每次重启之后就会失效

13.7.drf配置redis缓存

使用django-redis第三方库：http://django-redis-chs.readthedocs.io/zh_CN/latest/#id8 （文档说明）

（1）安装

pip install django-redis

（2）settings

# redis缓存
CACHES = {
    "default": {
        "BACKEND": "django_redis.cache.RedisCache",
        "LOCATION": "redis://127.0.0.1:6379",
        "OPTIONS": {
            "CLIENT_CLASS": "django_redis.client.DefaultClient",
        }
    }
}

13.8.drf的throttle设置api的访问速率

为了防止爬虫对服务器造成的重大压力，对数据进行访问速率限制就显得非常的重要了

官网使用说明：http://www.django-rest-framework.org/api-guide/throttling/

（1）settings中配置

REST_FRAMEWORK = {
    #限速设置
    'DEFAULT_THROTTLE_CLASSES': (
            'rest_framework.throttling.AnonRateThrottle',   #未登陆用户
            'rest_framework.throttling.UserRateThrottle'    #登陆用户
        ),
    'DEFAULT_THROTTLE_RATES': {
        'anon': '3/minute',         #每分钟可以请求两次
        'user': '5/minute'          #每分钟可以请求五次
    }
}

（2）goods/views.py中使用

from rest_framework.throttling import UserRateThrottle,AnonRateThrottle
class GoodsListViewSet(CacheResponseMixin,mixins.ListModelMixin, mixins.RetrieveModelMixin,viewsets.GenericViewSet):
　　.
　　.
　　throttle_classes = (UserRateThrottle, AnonRateThrottle)