如何在Views.py中进行变体以添加到购物车功能

如何解决如何在Views.py中进行变体以添加到购物车功能

1. 我只需要使添加到购物车中的内容具有变化性，例如S，M，L

2. 这不是Django Rest Framework，我只想使用Django

3. 我没有适用于该版本的表格，如果有错，请您帮我

4. 我正在关注JustDjango Ecommerce，但我正在使用代码构建自己的网站，并尝试仅使用Django添加一些变体。不使用Django Rest Framework

   class Food(models.Model):
   
       class NewManager(models.Manager):
           def get_queryset(self):
               return super().get_queryset() .filter(avail=True)
   
       title = models.CharField(max_length=100)
       price = models.DecimalField(max_digits=5,decimal_places=2)
       discount_price = models.FloatField(blank=True,null=True)
       category = models.ForeignKey(Category,on_delete=models.CASCADE,blank=True,null=True)
       Package = models.ForeignKey(Pack,null=True)
       per = models.CharField(choices=PR,max_length=2,null=True)
       top = models.BooleanField(_('Top Selling'),default=False)
       slug = models.SlugField()
       description = models.TextField()
       image = models.ImageField(blank=False,null=False)
       avail = models.BooleanField(_('Available'),default=True)
       navail = models.BooleanField(_('Not Available'),default=False)
   
       def __str__(self):
          return self.title
   
   
   
   class Variation(models.Model):
       item = models.ForeignKey(Food,on_delete=models.CASCADE)
       name = models.CharField(max_length=50)  # size
   
       class Meta:
           unique_together = (
               ('item','name')
           )
   
       def __str__(self):
           return self.name
   
   
   class ItemVariation(models.Model):
       variation = models.ForeignKey(Variation,on_delete=models.CASCADE)
       value = models.CharField(max_length=50)  # S,M,L
       attachment = models.ImageField(blank=True)
   
       class Meta:
           unique_together = (
               ('variation','value')
           )
   
       def __str__(self):
           return self.value
   
   class OrderItem(models.Model):
       user = models.ForeignKey(settings.AUTH_USER_MODEL,on_delete=models.CASCADE)
       ordered = models.BooleanField(default=False)
       item = models.ForeignKey(Food,on_delete=models.CASCADE)
       item_variations = models.ManyToManyField(ItemVariation)
       quantity = models.IntegerField(default=1)
   

   @login_required
   def add_to_cart(request,slug,*args,**kwargs):
       item = get_object_or_404(Food,slug=slug)
       variations = Variation.objects.all()
       minimum_variation_count = Variation.objects.filter(item=item).count()
       if len(variations) < minimum_variation_count:
           return redirect("resto:order")
   
       order_item_qs = OrderItem.objects.filter(
           item=item,user=request.user,ordered=False
       )
       for v in variations:
           order_item_qs = order_item_qs.filter(
               Q(item_variations__exact=v)
           )
   
           if order_item_qs.exists():
               order_item = order_item_qs.first()
               order_item.quantity += 1
               order_item.save()
           else:
               order_item = OrderItem.objects.create(
                   item=item,ordered=False
               )
               order_item.item_variations.add(*variations)
               order_item.save()
   
           order_qs = Order.objects.filter(user=request.user,ordered=False)
           if order_qs.exists():
               order = order_qs[0]
               if not order.items.filter(item__id=order_item.id).exists():
                   order.items.add(order_item)
                   return redirect("resto:order")
   
           else:
               ordered_date = timezone.now()
               order = Order.objects.create(
                   user=request.user,ordered_date=ordered_date)
               order.items.add(order_item)
               return redirect("resto:order")
   

  I add a Variation name "Sugar" just for Example when I click Add to Cart this Error show up.

   ValueError at /add-to-cart/item-1/
   Cannot query "Sugar": Must be "ItemVariation" instance.
       Request Method:  GET
       Request URL: http://127.0.0.1:8000/add-to-cart/item-1/
       Django Version:  2.2
       Exception Type:  ValueError
       Exception Value: Cannot query "Sugar": Must be "ItemVariation" instance.
       Exception Location:  C:\Users\Admin\djangoproj\cafe\cdc\lib\site-packages\django\db\models\sql\query.py in check_query_object_type,line 1065
       Python Executable:   C:\Users\Admin\djangoproj\cafe\cdc\Scripts\python.exe
       Python Version:  3.8.3
       Python Path: 
           ['C:\\Users\\Admin\\djangoproj\\cafe\\src','C:\\Users\\Admin\\djangoproj\\cafe\\cdc\\Scripts\\python38.zip','c:\\users\\admin\\appdata\\local\\programs\\python\\python38-32\\DLLs','c:\\users\\admin\\appdata\\local\\programs\\python\\python38-32\\lib','c:\\users\\admin\\appdata\\local\\programs\\python\\python38-32','C:\\Users\\Admin\\djangoproj\\cafe\\cdc','C:\\Users\\Admin\\djangoproj\\cafe\\cdc\\lib\\site-packages','c:\\users\\admin\\djangoproj\\cafe\\cdc\\src\\django-oscar-cash-on-delivery']
       Server time: Fri,25 Sep 2020 03:05:29 +0000

Error Screenshot

Error Screenshots (Traceback)

I add "Sugar" in Variation

In ItemVariation

解决方法

仅在您的for循环下面尝试替换：

order_item_qs = order_item_qs.filter(
            Q(item_variations__exact=v)
        )

使用：

order_item_qs = order_item_qs.filter(item_variations__variation=v)