#25409: Allow url and groups of urls to be easily tagged and selected
---------------------------------+--------------------
Reporter: atul-bhouraskar | Owner: nobody
Type: New feature | Status: new
Component: Core (URLs) | Version: master
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 1
Easy pickings: 0 | UI/UX: 0
---------------------------------+--------------------
== The Problem ==
Often (usually in middleware) processing has to be applied to a certain
URLs only eg CORS.
The usual way to specify this would be to create an additional set of
regex patterns identifying these urls - eg.
{{{
CORS_URLS_REGEX = r'^/api/.*$'
}}}
The middleware then typically matches the incoming request URL to the
regex and determines whether it is to be selected for processing.
This approach has several limitations including:
* It violates DRY as the regexes in the settings have to be synced with
the actual URL patterns
* Matching multiple patterns may require the app writer to essentially
reinvent URL patterns - poorly.
== The Proposal ==
Add an optional {{{tags}}} keyword argument to {{{django.conf.urls.url}}}
allowing a URL to be optionally tagged with one or more tags which can
then be retrieved via {{{HttpRequest.resolver_match.tags}}} in the
middleware / view etc.
{{{
urlpatterns = [
url(r'^$', views.home, name='home'),
url(r'^articles/$', views.show_articles, name='show-articles',
tags=['require_GET']),
url(r'^private/$', include(private_patterns),
tags=['login_required']),
url(r'^api/', include(api_patterns), tags=[
'cors_allowed', 'nologin_forbidden', 'ajax_required'
]),
]
}}}
In the example above, the {{{home}}} url has no tags, the {{{show-
articles}}} url is tagged {{{require_GET}}}, the urls under {{{private/}}}
are all tagged {{{login_required}}} while the the urls under {{{api/}}}
have multiple tags.
This allows app middleware to selectively process urls very easily:
{{{
class LoginRequiredMiddleware(object):
def process_view(self, request, view_func, view_args, view_kwargs):
if 'login_required' in request.resolver_match.tags and \
not request.user.is_authenticated():
return redirect('login')
class RequireGETMiddleware(object):
def process_view(self, request, view_func, view_args, view_kwargs):
if 'require_GET' in request.resolver_match.tags and request.method
!= 'GET':
return HttpResponseNotAllowed(['GET'])
class AjaxRequiredMiddleware(object):
def process_view(self, request, view_func, view_args, view_kwargs):
if 'ajax_required' in request.resolver_match.tags and not
request.is_ajax():
return HttpResponseForbidden()
class CorsMiddleware(object):
def process_view(self, request, view_func, view_args, view_kwargs):
if 'cors_allowed' in request.resolver_match.tags:
# continue CORS processing
}}}
I am attaching a patch that implements this tagging feature to
urlpatterns. It has tests (docs to be added). The change is fully
backwards compatible as specifying tags is completely optional, all
existing tests pass with the patch applied to master.
Comments welcome!
--
Ticket URL: <https://code.djangoproject.com/ticket/25409>
Django <https://code.djangoproject.com/>
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