python学习之美多商城(二十一):购物车部分：购物车数据的增查改删、商品选中状态、购物车全选、合并购物车

一、添加到购物车:

1.后端接口设计:

请求方式: POST /cart
请求参数: json或表单

参数	类型	是否必须	说明
sku_id	int	是	商品sku_id
count	int	是	数量
selected	bool	否	是否勾选, 默认为True

返回值: JSON

参数	类型	是否必须	说明
sku_id	int	是	商品sku_id
count	int	是	数量
selected	bool	否	是否勾选, 默认为True

访问此接口,无论用户是否登录, 前端请求都需携带请求头Authorization，由后端判断是否登录

2.后端实现:

因为前端可能携带cookie，为了保证跨域请求中，允许后端使用cookie，确保在配置文件有如下设置:

# meiduo_mall/settings/
CORS_ALLOW_CREDENTIALS = True

创建carts子应用:

# meiduo_mall/apps/
python ../../ startapp carts

编写视图:
注意:因为前端请求时携带了Authorization请求头(主要是JWT), 如果用户为登录, 请求头的JWT无意义(没有值), 为了防止REST framework框架在验证此无意义的请求头时抛出401验证异常, 因此在视图中需要做两个处理:

• 重写perform_authentication()方法, 此方法是REST framework检车用户身份的方法;
• 在获取属性时捕获异常,REST framework
  在返回时会检查Authorization请求头，无效的Authorization请求头会导致抛出异常

在carts/中创建视图:

# meiduo_mall/apps/carts/

import base64
import pickle

from django.shortcuts import render

# Create your views here.
from django_redis import get_redis_connection
from rest_framework import status
from rest_framework.response import Response
from rest_framework.views import APIView

from carts import constants
from goods.models import SKU


class CartVIew(APIView):
    """购物车"""
    def perform_authentication(self, request):
        """
        重写父类的用户验证方法,不在进入视图前就检查JWT
        :param request:
        :return:
        """
        pass

    def post(self, request):
        """
        添加购物车
        :param request:
        :return:
        """
        params = request.data
        skuid = params.get('sku_id')
        count = params.get('count')
        selected = params.get('selected', True)
        # 检查数据
        try:
            sku = SKU.objects.get(id = skuid)
        except Exception as e:
            return Response({'data':"商品查找失败..."})
        try:
            count = int(count)
        except Exception as e:
            return Response({'data': "传参不正确..."})

        # 验证用户
        try:
            user = request.user
        except Exception as e:
            user = None

        if user is not None and user.is_authenticated:
            # 用户已经登录,在redis中保存
            redis_conn = get_redis_connection('cart')
            pl = redis_conn.pipeline()
            # 记录购物车商品数量
            pl.hincrby('cart_{}'.format(user.id), skuid, count)
            # 记录购物车的勾选项
            # 勾选
            if selected:
                pl.sadd('cart_selected_{}'.format(user.id),skuid)
            pl.execute()
            return Response({'sku_id':skuid,
                             'count':count,
                             'selected':selected}, status=status.HTTP_201_CREATED)
        else:
            # 用户未登录, 在cookie中保存
            # {
            #     1001:{'count':10,'selected':true},
            #     ...
            # }
            # 使用pickle序列化购物车数据, pickle操作的是bytes类型
            cart = request.COOKIES.get('cart')
            if cart is not None:
                cart = pickle.loads(base64.b64decode(cart))
            else:
                cart = {}

            sku = cart.get(skuid)
            if sku:
                count += int(sku.get('count'))
            cart[skuid] = {
                'count': count,
                'selected': selected
            }
            cookie_cart = base64.b64encode(pickle.dumps(cart))
            response = Response({'sku_id':skuid,
                             'count':count,
                             'selected':selected}, status=status.HTTP_201_CREATED)
            response.set_cookie('cart',cookie_cart, max_age=constants.CART_COOKIE_EXPIRES)
            return response

在carts中新建 常量文件

#meiduo_mall/apps/carts/

# 购物车cookie的有效期
CART_COOKIE_EXPIRES = 365 * 24 * 60 * 60

二、查询购物车:

1.后端接口设计:

请求方式: GET /cart/
请求参数: 无
返回值: json

参数	类型	是否必须	说明
id	int	是	商品sku_id
name	str	是	商品名称
count	int	是	商品数量
sku.default_image_url	str	是	商品默认图片路径
price	decimal	是	商品单价
selected	bool	是	商品是否被勾选

[
    {
        "id": 9,
        "count": 3,
        "name": "华为 HUAWEI P10 Plus 6GB+64GB 钻雕金 移动联通电信4G手机 双卡双待",
        "default_image_url": ":8888/group1/M00/00/02/CtM3BVrRcUeAHp9pAARfIK95am88523545",
        "price": "3388.00",
        "selected": true
    },
    {
        "id": 12,
        "count": 1,
        "name": "华为 HUAWEI P10 Plus 6GB+64GB 钻雕蓝 移动联通电信4G手机 双卡双待",
        "default_image_url": ":8888/group1/M00/00/02/CtM3BVrRdICAO_CRAAcPaeOqMpA2024091",
        "price": "3388.00",
        "selected": true
    }
]

2.后端实现:

在carts/的视图类中,增加get方法:

# meiduo_mall/apps/carts/

class CartVIew(APIView):
    """购物车"""
    ...
	
	def get(self, request):
        """
        查询购物车数据
        :param request:
        :return:
        """
        try:
            user = request.user
        except Exception as e:
            user = None

        if user is not None and user.is_authenticated:
            # 用户已登录,从redis中获取数据
            redis_conn = get_redis_connection('cart')
            redis_cart = redis_conn.hgetall('cart_{}'.format(user.id))
            redis_selected = redis_conn.smembers('cart_selected_{}'.format(user.id))

            cart = {}
            for sku_id, count in redis_cart.items():
                cart[int(sku_id)] = {
                    'count':int(count),
                    'selected':sku_id in redis_selected
                }
        else:
            # 用户未登录, 从cookie中读取
            cart = request.COOKIES.get('cart')
            if cart:
                cart = pickle.load(base64.b64decode(cart))
            else:
                cart = {}

        # 遍历处理购物车数据
        skus = SKU.objects.filter(id__in=cart.keys())
        skus_list = []
        for sku in skus:
            sku_dict = {}
            sku_dict['id'] = sku.id
            sku_dict['count'] = cart[sku.id]['count']
            sku_dict['name']=sku.name
            sku_dict['default_image_url'] = sku.default_image_url
            sku_dict['price'] = sku.price
            sku_dict['selected'] = cart[sku.id]['selected']
            skus_list.append(sku_dict)

        return Response(skus_list)

三、修改购物车数据:

请求方式: PUT /cart/
请求参数: json或表单类型

参数	类型	是否必须	说明
sku_id	int	是	商品sku id
count	int	是	修改后的数量
selected	bool	是	修改后的选中状态

返回数据: JSON

参数	类型	是否必须	说明
sku_id	int	是	商品sku id
count	int	是	修改后的数量
selected	bool	是	修改后的选中状态

2.后端实现:

在carts/中修改视图，添加put方法

# meiduo_mall/apps/carts/

class CartVIew(APIView):
    """购物车"""
    ...
	def put(self, request):
        """
        修改购物车数据
        :param request:
        :return:
        """
        params = request.data
        skuid = params.get('sku_id')
        count = params.get('count')
        selected = params.get('selected', True)
        # 检查数据
        try:
            sku = SKU.objects.get(id=skuid)
        except Exception as e:
            return Response({'data': "商品查找失败..."})
        try:
            count = int(count)
        except Exception as e:
            return Response({'data': "传参不正确..."})

        # 验证用户
        try:
            user = request.user
        except Exception as e:
            user = None

        if user is not None and user.is_authenticated:
            # 用户已经登录,在redis中保存
            redis_conn = get_redis_connection('cart')
            pl = redis_conn.pipeline()
            # 记录购物车商品数量
            pl.hincrby('cart_{}'.format(user.id), skuid, count)
            # 记录购物车的勾选项
            # 勾选
            if selected:
                pl.sadd('cart_selected_{}'.format(user.id),skuid)
            pl.execute()
            return Response({'sku_id':skuid,
                             'count':count,
                             'selected':selected}, status=status.HTTP_201_CREATED)
        else:
            # 用户未登录, 在cookie中保存
            # {
            #     1001:{'count':10,'selected':true},
            #     ...
            # }
            # 使用pickle序列化购物车数据, pickle操作的是bytes类型
            cart = request.COOKIES.get('cart')
            if cart is not None:
                cart = pickle.loads(base64.b64decode(cart))
            else:
                cart = {}

            sku = cart.get(skuid)
            if sku:
                count += int(sku.get('count'))
            cart[skuid] = {
                'count': count,
                'selected': selected
            }
            cookie_cart = base64.b64encode(pickle.dumps(cart))
            response = Response({'sku_id':skuid,
                             'count':count,
                             'selected':selected}, status=status.HTTP_201_CREATED)
            response.set_cookie('cart',cookie_cart, max_age=constants.CART_COOKIE_EXPIRES)
            return response

四、删除购物车数据:

1.后端接口设计:

请求方式: DELETE /cart/
请求参数:

参数	类型	是否必须	说明
sku_id	int	是	商品sku_id

返回数据: 无 状态码204

2.后端代码:

在carts/的视图类中添加delete方法

# meiduo_mall/apps/carts/

class CartVIew(APIView):
    """购物车"""
    ...
    def delete(self, request):
        """
        删除购物车数据
        :param request:
        :return:
        """
        params = request.data
        skuid = params.get('sku_id')
        # 检查数据
        try:
            sku = SKU.objects.get(id=skuid)
        except Exception as e:
            return Response({'data': "商品查找失败..."})

        # 验证用户
        try:
            user = request.user
        except Exception as e:
            user = None

        if user is not None and user.is_authenticated:
            redis_conn = get_redis_connection('cart')
            pl = redis_conn.pipeline()
            pl.hdel('cart_{}'.format(user.id), skuid)
            pl.srem('cart_selected_{}'.format(user.id), skuid)
            pl.execute()
            return Response(status=status.HTTP_204_NO_CONTENT)
        else:
            response = Response(status=status.HTTP_204_NO_CONTENT)

            # 使用pickle序列化购物车数据，pickle操作的是bytes类型
            cart = request.COOKIES.get('cart')
            if cart is not None:
                cart = pickle.loads(base64.b64decode(cart.encode()))
                if skuid in cart:
                    del cart[skuid]
                    cookie_cart = base64.b64encode(pickle.dumps(cart)).decode()
                    # 设置购物车的cookie
                    # 需要设置有效期，否则是临时cookie
                    response.set_cookie('cart', cookie_cart, max_age=constants.CART_COOKIE_EXPIRES)
            return response

五、商品选中/取消选中:

1.后台接口设计:

请求方式:
请求参数: JSON或表单

参数	类型	是否必须	说明
selected	bool	是	是否全选，true表示全选，false表示取消全选

返回数据: JSON

返回值	类型	是否必须	说明
message	str	是	ok

2.后端实现:

在carts/的视图类中添加put方法:

# meiduo_mall/apps/carts/
class CartVIew(APIView):
    """购物车"""
    ...
    def put(self, request):
        """
        修改全部选中状态
        :param request:
        :return:
        """
        params = request.data
        skuid = params.get('sku_id')
        count = params.get('count')
        selected = params.get('selected', True)
        # 检查数据
        try:
            sku = SKU.objects.get(id=skuid)
        except Exception as e:
            return Response({'data': "商品查找失败..."})
        try:
            count = int(count)
        except Exception as e:
            return Response({'data': "传参不正确..."})

        # 验证用户
        try:
            user = request.user
        except Exception as e:
            user = None

        if user is not None and user.is_authenticated:
            # 用户已经登录,在redis中保存
            redis_conn = get_redis_connection('cart')
            pl = redis_conn.pipeline()
            # 记录购物车商品数量
            pl.hincrby('cart_{}'.format(user.id), skuid, count)
            # 记录购物车的勾选项
            # 勾选
            if selected == True:
                pl.sadd('cart_selected_{}'.format(user.id), skuid)
            elif selected == False:
                pl.srem('cart_selected_{}'.format(user.id), skuid)
            pl.execute()
            return Response({'message': 'OK'}, status=status.HTTP_204_NO_CONTENT)
        else:
            # 用户未登录, 在cookie中保存
            # {
            #     1001:{'count':10,'selected':true},
            #     ...
            # }
            # 使用pickle序列化购物车数据, pickle操作的是bytes类型
            cart = request.COOKIES.get('cart')
            if cart is not None:
                cart = pickle.loads(base64.b64decode(cart))
            else:
                cart = {}

            sku = cart.get(skuid)
            if sku:
                count += int(sku.get('count'))
            cart[skuid] = {
                'count': count,
                'selected': selected
            }
            cookie_cart = base64.b64encode(pickle.dumps(cart))
            response = Response({'message': 'OK'}, status=status.HTTP_204_NO_CONTENT)
            response.set_cookie('cart', cookie_cart, max_age=constants.CART_COOKIE_EXPIRES)
            return response

六、购物车全选:

请求方式: PUT /cart/selection/
请求参数: json或表单

参数	类型	是否必须	说明
select	bool	是	是否全选，true表示全选，false表示取消全选

返回数据: JSON

参数	类型	是否必须	说明
message	str	是	ok

2.后端实现:

在carts/中重新创建一个视图:

# meiduo_mall/apps/carts/
...
class CartSelectAllView(APIView):
    """
    购物车全选
    """
    def perform_authentication(self, request):
        """
        重写父类的用户验证方法,不在进入视图前就检查JWT
        :param request:
        :return:
        """
        pass


    def put(self, request):
        """
        购物车全选/取消全选
        :param request:
        :return:
        """
        params = request.data
        selected = params.get('selected')

        # 检查参数
        if not isinstance(selected, bool):
            return Response({'message': '参数类型错误'},status=status.HTTP_400_BAD_REQUEST)

        try:
            user = request.user
        except Exception as e:
            user = None

        if user is not None and user.is_authenticated:
            # 用户已登录，在redis中保存
            redis_conn = get_redis_connection('cart')
            cart = redis_conn.hgetall('cart_%s' % user.id)
            sku_id_list = cart.keys()

            if selected:
                # 全选
                redis_conn.sadd('cart_selected_%s' % user.id, *sku_id_list)
            else:
                # 取消全选
                redis_conn.srem('cart_selected_%s' % user.id, *sku_id_list)
            return Response({'message': 'OK'})
        else:
            # cookie
            cart = request.COOKIES.get('cart')

            response = Response({'message': 'OK'})

            if cart is not None:
                cart = pickle.loads(base64.b64decode(cart.encode()))
                for sku_id in cart:
                    cart[sku_id]['selected'] = selected
                cookie_cart = base64.b64encode(pickle.dumps(cart)).decode()
                # 设置购物车的cookie
                # 需要设置有效期，否则是临时cookie
                response.set_cookie('cart', cookie_cart, max_age=constants.CART_COOKIE_EXPIRES)

            return response

七、登录合并购物车:

用户登录时,将cookie中的购物车数据合并到redis中,并清除cookie中的购物车数据。
普通登录和第三方登录都要合并,所以要将合并逻辑放到公共函数中实现。
在carts/中创建merge_cart_cookie_to_redis方法:

# meiduo_mall/apps/carts/