django url regex to match optional parameters

Question

I need a regex that should match the following strings:

users/24
users/24/
users/24/sam
users/24/sam/
users/24/sam/tab_name
users/24/sam/tab_name/

where, pk=24, username=sam, tab=tab_name

So far I have a url as:

url(r'^users/(?P<pk>\d+)/(?P<username>[-\w\d]+)?/?(?P<tab>[-\w\d]+)?/?', vw.ProfileView.as_view(), name='profile')

The above url matches everything above. But while using

{% url 'profile' pk=24 username="sam" tab="tab_name" %}

the output is : users/samtab_name

I know the problem here i.e, /? optional slash. But I don't want it to be optional when using {% url 'profile' pk=24 username="sam" tab="tab_name" %}

Help me with this.

Try [`^users/(?P\d+)(?:/(?P[-\w]+))?(?:/(?P[-\w]+))?/?`](https://regex101.com/r/TIKklT/1). Not sure you need the last `/?` though. — Wiktor Stribiżew, Aug 08 '18 at 12:52
I suggest you make the slash required (use `/` instead of `/?`). Then the default Django behaviour will be to redirect to the URLs with the slash (e.g. `/users/24/sam` -> `/users/24/sam/`). See the docs on [`append_slash`](https://docs.djangoproject.com/en/2.1/ref/settings/#append-slash) for more info. — Alasdair, Aug 08 '18 at 13:00
@WiktorStribiżew Your regex did the work though. I would appreciate if you explained `?:` — whitehat, Aug 08 '18 at 13:13

score 2 · Accepted Answer · answered Aug 08 '18 at 13:14

You may make your / obligatory by placing them together with the named capturing groups inside optional non-capturing groups:

^users/(?P<pk>\d+)(?:/(?P<username>[-\w]+))?(?:/(?P<tab>[-\w]+))?/?

See the regex demo.

Note that \w already matches digits, so you do not need \d inside the character classes.

Details

^ - start of string
users/ - a literal substring
(?P<pk>\d+) - a named capturing group "pk" matching 1+ digtis
(?:/(?P<username>[-\w]+))? - an optional non-capturing group (there is ? quantifier after the closing )) matching
- / - a / char
- (?P<username>[-\w]+) - Group "username": 1+ word or - chars
(?:/(?P<tab>[-\w]+))? - an optional non-capturing group matching
- / - a / char
- (?P<tab>[-\w]+) - Group "tab": 1+ word or - chars
/? - an optional / char.

django url regex to match optional parameters

1 Answers1