How to get the current urlname using Django?

Question

I have to build an url dynamically according to the current url. Using the {% url %} tag is the easiest way to do it, but I need the current url name to generate the new one dynamically.

How can I get the url name attached to the urlconf that leads to the current view?

EDIT : I know I can manually handcraft the url using get_absolute_url but I'd rather avoid it since it's part of a lecture and I would like to demonstrate only one way to build urls.

The students know how to use {% url %}. They are know facing a problem when they have to generate a more complete url based on the current one. The easiest way is to use {% url %} again, with some variations. Since we have named url, we need to know how to get the name of the url that called the current view.

Answer 1

http://docs.djangoproject.com/en/dev/ref/request-response/#django.http.HttpRequest.get_full_path

Answer 2

It's a little unclear from your question, but http://docs.djangoproject.com/en/dev/topics/http/urls/ will likely provide an explanation to what you're after.

Especially useful to note how Django processes requests:

When a user requests a page from your Django-powered site, this is the algorithm the system follows to determine which Python code to execute:

1. Django determines the root URLconf module to use. Ordinarily, this is the value of the ROOT_URLCONF setting, but if the incoming HttpRequest object has an attribute called urlconf (set by middleware request processing), its value will be used in place of the ROOT_URLCONF setting.
2. Django loads that Python module and looks for the variable urlpatterns. This should be a Python list, in the format returned by the function django.conf.urls.defaults.patterns().
3. Django runs through each URL pattern, in order, and stops at the first one that matches the requested URL.
4. Once one of the regexes matches, Django imports and calls the given view, which is a simple Python function. The view gets passed an HttpRequest as its first argument and any values captured in the regex as remaining arguments.

If you're just after the full path, you can try:

http://docs.djangoproject.com/en/dev/ref/request-response/#django.http.HttpRequest.get_full_path

I hope that helps - it indicates how to use the URLconf module, and hopefully will help point you in the right direction.

Answer 3

Clarification of the question: "In a view, how do you get the name of a urlpattern that points to it, assuming there is exactly one such urlpattern."

This may be desirable for the reasons stated: from within the view, we want a DRY way of getting a url to the same view (we don't want to have to know our own urlpattern name).

Short answer: It's not really simple enough to teach your class, but it might be a fun thing for you to do in an hour or two and throw up on GitHub.

If you really wanted to do this, you would have to subclass RegexURLResolver and modify the resolve method to return the matched pattern (from which you can get the pattern name) instead of the view and keyword/value pairs. http://code.djangoproject.com/browser/django/trunk/django/core/urlresolvers.py#L142

You could then create a decorator or perhaps more appropriately middleware that uses this subclass to get the pattern name and store that value somewhere in the request so that views can use it.

If you actually want to do that and you run across some trouble, let me know and I can probably help.

For your class, I would just have them hardcode the pattern name in the view or template. I believe this is the acceptable way of doing it.

Update: The more I think about this, the more I would discourage trying to get a urlpattern name in a view. urlpattern parameters are fairly independent of the parameters of the view they point to. If you want to point to a certain url, you need to know how the urlpattern works, not just how the view works. If you need to know how the urlpattern works, you might as well have to know the name of the urlpattern.