django.urls.exceptions.NoReverseMatch: ... is not a registered namespace

Using Django
1

Hi there!

I have a Django project with a middleware which sets request.urlconf depending on the host header. Here’s the middleware:

class VhostMiddleware:
def __init__(self, get_response):
    self.get_response = get_response
    self.vhosts = {"hosta.example.com": "app_a.urls", "host_b.example.com": "app_b.urls"}

def __call__(self, request):
    urlconf = self.vhosts.get(request.get_host())
    request.urlconf = urlconf
    response = self.get_response(request)
    return response

For app_a I have a set of urls:

app_name = "app_a"
urlpatterns = [
    path("feedback/", FeedbackCreateView.as_view(), name="feedback_create"),
    path("feedback-thanks/", feedback_thanks, name="feedback_thanks"),
]

The template for feedback/ has a form which calls the view:

<form action="{% url "app_a:feedback_create" %}" method="post">

Now the problem is that the template does not like “app_a:feedback_create” and raises:

django.urls.exceptions.NoReverseMatch: … is not a registered namespace

When instead I do:

<form action="{% url "feedback_create" %}" method="post">

everything works great. Could be because the middleware loads just one urlconf and the namespace becomes irrelevat?

Thank you!

2

Have you tried it without the namespace? It’s looking for one, and the app name is not a namespace. Typically you would define a namespace in the root urls.py in a path that includes your app_a.urls. Since this IS your root urls.py because of the middleware, the namespace isn’t defined, or needed.

3

Yeah, I came to the same conclusion and in the end I solved calling url without the namespace.