html response before saving object

[pyl...@gmail.com]

Hi Guys, 

I've update my site from django 1.3 to 1.5

The site works fine, except for a view, the template renders before the obj.save() in the view:

def cart(request):

    try:

        cart = Cart.objects.prefetch_related('cartitem_set__product__category').get(id=request.session['cart_id'])

    except (KeyError, Cart.DoesNotExist) as e:

        cart = Cart()

        cart.save()

        request.session['cart_id'] = cart.id

    if 'add' in request.GET:

        try:

            product = Product.objects.get(slug=request.GET['add'], active=True)

            cart_item = CartItem.objects.get(product=product, cart=cart)

        except CartItem.DoesNotExist:

            cart_item = CartItem(product=product, cart=cart)

            cart_item.save()

        except Product.DoesNotExist:

            pass

    response_args = {'cart': cart}

    return render_to_response('products/cart.html', response_args, context_instance=RequestContext(request))

I don't know why this happens

any help? something has changed? now the database save is async?

[Collin Anderson]

database save is not async.

a few possibilities:

- does the product exist?

- is the cart_item really not created? (or is the cart the thing not being created?)

- is the prefetch_related pre-caching the related cart items, so in the template it doesn't see the new item? (hint: redirect to the same page to load the page again)

- are you using transactions?

- you could moving around some print statements, or my favorite: assert False, to see what code is actually getting run.

also, while you're upgrading (or after), you can now use simpler code for that last line:

return render(request, 'products/cart.html', response_args)

[pyl...@gmail.com]

- does the product exist?

Yes, 

- is the cart_item really not created? (or is the cart the thing not being created?)

The cartItem is created, but it shown if I request again the url

1) request: /cart/?add=productslug

2) response: without the new item

3) request : /cart/

4) response: the item now is shown

- are you using transactions?

No 

 

- is the prefetch_related pre-caching the related cart items, so in the template it doesn't see the new item? (hint: redirect to the same page to load the page again)

I did not know that about prefetch_related, I have removed it and now working as expected.

 

also, while you're upgrading (or after), you can now use simpler code for that last line:

return render(request, 'products/cart.html', response_args)

Thanks :)