# NoReverseMatchError, path, and args vs. kwargs

**URL:** <https://forum.djangoproject.com/t/noreversematcherror-path-and-args-vs-kwargs/1923>\
**Category:** Using Django\
**Created:** [April 12, 2020, 5:43pm UTC](https://forum.djangoproject.com/t/noreversematcherror-path-and-args-vs-kwargs/1923 "2020-04-12T17:43:31Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![harrington59802](https://avatars.discourse-cdn.com/v4/letter/h/a183cd/32.png) [@harrington59802](https://forum.djangoproject.com/u/harrington59802)\
**Post date:** [April 12, 2020, 5:43pm UTC](https://forum.djangoproject.com/t/noreversematcherror-path-and-args-vs-kwargs/1923/1 "2020-04-12T17:43:31Z")

</div>

Hi everyone,

```
I have the following view: 
    def update_cart(request, id):
    cart = Cart.objects.all()
    product = Product.objects.get(pk=id)
    cart.products.add(product)
    return HttpResponseRedirect(reverse("update_cart_url", args=(product.id)))

And URL pattern in my project level urls.py (after importing update_cart from carts.views):
        path('cart/<int:product.id>/', update_cart, name="update_cart_url")

Which are called in a template: 
    <h3>{{ product.name}}<a href=" {% url 'update_cart_url' product.id %}">Add to Cart</a></h3>

When rendering the template, I receive the following error: 
    NoReverseMatch at /webCart/detail/6/
Reverse for 'update_cart_url' with arguments '(6,)' not found. 1 pattern(s) tried: ['cart/<int:product\\.id>/$']

```

Note that the argument 6 above correctly matches the id of the item that the template was attempting to render.

There are lots of resources online in respect to this exception, and reading through them I believe I narrowed down my problem to several possibilities:

1. I am using args when I should be using kwargs or vice versa

2. I am attempting to reverse a URL by using path instead of url in urls.py

3. Should the url pattern be defined within the app directory rather than the project directory?

Does anyone have any ideas?

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<div class="post-metadata">

**Author:** ![adamchainz](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/adamchainz/32/26_2.png) [@adamchainz](https://forum.djangoproject.com/u/adamchainz)\
**Post date:** [April 12, 2020, 6:41pm UTC](https://forum.djangoproject.com/t/noreversematcherror-path-and-args-vs-kwargs/1923/2 "2020-04-12T18:41:52Z")

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Dots aren’t supported in url pattern variable names. Use an underscore instead and your problem should be solved.

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**Author:** ![KenWhitesell](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/kenwhitesell/32/280_2.png) [@KenWhitesell](https://forum.djangoproject.com/u/KenWhitesell)\
**Post date:** [April 12, 2020, 6:44pm UTC](https://forum.djangoproject.com/t/noreversematcherror-path-and-args-vs-kwargs/1923/3 "2020-04-12T18:44:05Z")

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I believe the issue may be here:

> [@harrington59802](#):
>
> path(‘cart/int:product.id/’, update\_cart, name=“update\_cart\_url”)

The url just contains an integer, which you can then use as the parameter being passed to your view to retrieve the specific object to which it refers.

try:

```
path('cart/<int:id>/', update_cart, name="update_cart_url")

```

Also, and I’m not sure if it makes a difference here, but:

> [@harrington59802](#):
>
> return HttpResponseRedirect(reverse(“update\_cart\_url”, args=(product.id)))

I believe args needs to be an iterable. This is one of those python gotchas that gets me all-too-often. Try either:

```
return HttpResponseRedirect(reverse("update_cart_url", args=(product.id,)))

```

or

```
return HttpResponseRedirect(reverse("update_cart_url", args=[product.id]))

```

In the first example, adding the trailing comma forces args to be a tuple and not just the singular value. In the second, you’re definitely passing a list - both of which are iterables.

Ken

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<div class="post-metadata">

**Author:** ![harrington59802](https://avatars.discourse-cdn.com/v4/letter/h/a183cd/32.png) [@harrington59802](https://forum.djangoproject.com/u/harrington59802)\
**Post date:** [April 12, 2020, 11:16pm UTC](https://forum.djangoproject.com/t/noreversematcherror-path-and-args-vs-kwargs/1923/5 "2020-04-12T23:16:44Z")

</div>

Thank you both, this is super helpful. The he tutorial is helpful as well.

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<div class="post-metadata">

**Author:** ![adamchainz](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/adamchainz/32/26_2.png) [@adamchainz](https://forum.djangoproject.com/u/adamchainz)\
**Post date:** [April 13, 2020, 8:10am UTC](https://forum.djangoproject.com/t/noreversematcherror-path-and-args-vs-kwargs/1923/6 "2020-04-13T08:10:39Z")

</div>

So Django wasn’t parsing your URL attempt correctly - it would see the dot in `<int:product.id>` and “skip over” trying to convert it. It therefore didn’t hit its built-in warning that you’ve typed something that’s not a valid identifier.

I’ve made a [ticket](https://code.djangoproject.com/ticket/31459) and [PR](https://github.com/django/django/pull/12710) to try fix this for future versions in Django, so others won’t hit the same problem again 🙂

* * *

@KenWhitesell was right about the brackets for the tuple as well. I prefer using lists wherever possible for this reason. See [my post](https://adamj.eu/tech/2019/07/05/tuples-versus-lists-in-python/).