django - url with no argument to take a default value

Question

Suppose, this is an `url` which takes an argument (here, `book_id`) and pass the value to the `views`: ``` url(r'^/(?P<book_id>\w+)/$', 'pro.views.book', name='book'), ``` Is it possible for a url which takes an argument, but, if no argument is given, take a default value. If possible may be in the `views` too. I am sorry if this is a lame question, but I really need to know. Any help or suggestion will be grateful. Thank you

Accepted Answer

Make the capturing pattern optional, and remember to deal with a trailing slash appropriately. I'd find a noncapturing group around the capturing group the safest way to do that: ``` url(r'^(?:(?P\w+)/)?$', 'pro.views.book', name='book'), ``` Then in the views, declare a default for the argument: ``` def book(request, book_id='default'): ``` If you find that URL pattern ugly, you can bind two regexps to the same view function: ``` url(r'^(?P\w+)/$', 'pro.views.book', name='book'), url(r'^$', 'pro.views.book', name='default_book'), ``` Following Alasdair's reminder, I have removed the leading slash. I thought that looked odd.

django - url with no argument to take a default value

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