python Django模型管理器

Posted 2021-05-09

class CartManager(models.Manager):
    '''
    A custom Manager method can return anything you want. 
    It doesn’t have to return a QuerySet.
    '''
    def new(self, user=None):
        '''使用模型管理器创建一个新对象'''
        user_obj = None
        if user is not None:
            if user.is_authenticated():
                user_obj = user
        return self.model.objects.create(user=user_obj)
    
    def new_or_get(self, request):
        cart_id = request.session.get("cart_id", None)
        qs = self.get_queryset().filter(id=cart_id)
        if qs.count() == 1:
            # 使用已存在的cart对象，修改其user属性
            cart_obj = qs.first()
            if request.user.is_authenticated() and cart_obj.user is None:
                cart_obj.user = request.user
                cart_obj.save()
        else:
            # 创建新的cart对象，并将其与session绑定
            cart_obj = self.new(user=request.user)
            request.session['cart_id'] = cart_obj.id
        return cart_obj