python之使用表单字段更新 Django 模型

我正在尝试使用前端的整数表单字段更新我的库存模型的数量。我可以添加新的库存项目，但我想更新现有项目。这是我的代码:

来自 VIEWS.PY

def view_inventory(request, slug): 
 
if request.method == 'POST': 
    quantity_add = addQuantity(request.POST) 
    if quantity_add.is_valid(): 
        cd = quantity_add.cleaned_data 
        addq=Inventory(quantity = cd.get('quantity')) 
        addq.save() 
 
quantity_add=addQuantity() 
 
return render(request, 'inv/view_inventory.html', { 
    'item': get_object_or_404(Inventory.objects.all(), slug=slug), 
    'form' : quantity_add, 
    }) 

来自模型.PY

class Inventory(models.Model): 
    quantity = models.IntegerField() 
    name = models.CharField(max_length=150, unique = True) 
    slug = models.SlugField(unique = True) 
    date = models.DateTimeField(auto_now_add=True) 
    description = models.CharField(max_length=250) 
    category    = models.ForeignKey(Category, null=True, blank=True) 
    def __unicode__(self): 
        return self.name 
    @permalink 
    def get_absolute_url(self): 
        return ('view_inventory', None, { 'slug' : self.slug }) 
 
    class Meta: 
        ordering = ['-date'] 

来自 URLS.PY

url(r'^(?P<slug>[\w\-]+)/$', 'inv.views.view_inventory', name='view_inventory'), 

请您参考如下方法:

你只需要获取记录然后更新它:

 def view_inventory(request, slug): 
 
  if request.method == 'POST': 
        quantity_add = addQuantity(request.POST) 
        if quantity_add.is_valid(): 
            cd = quantity_add.cleaned_data 
            old_inventory = Inventory.objects.get(id=something here) #id or pk or whatever you want 
            old_inventory.quantity = cd.get('quantity') 
            old_inventory.save() 
 
    quantity_add=addQuantity() 
 
    return render(request, 'inv/view_inventory.html', { 
        'item': get_object_or_404(Inventory.objects.all(), slug=slug), 
        'form' : quantity_add, 
        })