Vue + Django 2.0.6 学习笔记 10.1 加入购物车功能的实现

比眉伴天荒 2022-01-06 04:09 213阅读 0赞

1. models.py的修改

class ShoppingCart(models.Model):
        """
        购物车
        """
        user = models.ForeignKey(User, verbose_name=u'用户', on_delete=models.CASCADE)
        goods = models.ForeignKey(Goods, verbose_name=u'商品', on_delete=models.CASCADE)
        nums = models.IntegerField(default=0, verbose_name=u'购买数量')
        add_time = models.DateTimeField(default=datetime.now, verbose_name=u'添加时间')
    
        class Meta:
            verbose_name = u'购物车'
            verbose_name_plural = verbose_name
    # 建立联合唯一
            unique_together = ('user', 'goods')
    
        def __str__(self):
            return "%s(%d)".format(self.goods.name, self.nums)

serializers.py

from rest_framework import serializers
    
    from goods.models import Goods
    from .models import ShoppingCart
    
    # 用Serializer而不是ModelSerializer的原因;
    # 1.更灵活2.因为我们建立了联合唯一。所以如果使用ModelSerializer的话会去校验是否唯一
    #          但是购物车有这么一个情况，就是在点击添加购物车的按钮时，会判断购物车是否有
    #          ，如果有。不是抛异常，而是nums字段加1  所以如果用ModelSerializer的话会
    #          抛异常，所以这里需要自定义。
    class ShopCartSerializer(serializers.Serializer):
        user = serializers.HiddenField(
            default=serializers.CurrentUserDefault()
        )
        nums = serializers.IntegerField(required=True, min_value=1,label="数量",
                                        error_messages={
                                            "min_value":"商品数量不能小于1",
                                            "required": '请选择购买数量'
                                        })
    # goods是外键 所以需要用到PrimaryKeyRelatedField。并且指定外键的model类
        goods = serializers.PrimaryKeyRelatedField(required=True, queryset=Goods.objects.all())
    
    # 重写create函数，已满足我们的功能需求
        def create(self, validated_data):
    # user对象是保存在self.context["中"]
    # validated_data中的数据类型已经做好转换了
            user = self.context["request"].user
            nums = validated_data['nums']
            goods = validated_data['goods']
    
    # 是否存在，是就nums加数量 否就创建记录
            existed = ShoppingCart.objects.filter(user = user, goods = goods)
            if existed:
                existed = existed[0]
                existed.nums += nums
                existed.save()
            else:
                existed = ShoppingCart.objects.create(**validated_data)
            return existed

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
    
    # Create your views here.
    
    class ShoppingCartViewset(viewsets.ModelViewSet):
        """
        购物车功能
        list:
            获取购物车详情
        create:
            加入购物车
        delete:
            删除购物车记录
        """
        permission_classes = (IsAuthenticated, IsOwnerOrReadOnly)
        authentication_classes = (JSONWebTokenAuthentication, SessionAuthentication)
        serializer_class = ShopCartSerializer
    
        def get_queryset(self):
            return ShoppingCart.objects.filter(user=self.request.user)

urls.py

from trade.views import ShoppingCartViewset
    
    #购物车
    router.register('shopcarts', ShoppingCartViewset, base_name='shopcarts')

关于PrimaryKeyRelatedField的官方文档

[https://www.django-rest-framework.org/api-guide/relations/\#primarykeyrelatedfield][https_www.django-rest-framework.org_api-guide_relations_primarykeyrelatedfield]s

完结

[https_www.django-rest-framework.org_api-guide_relations_primarykeyrelatedfield]: https://www.django-rest-framework.org/api-guide/relations/#primarykeyrelatedfield