Python regex with question mark literal

Question

I'm using Django's URLconf, the URL I will receive is /?code=authenticationcode
I want to match the URL using r'^\?code=(?P<code>.*)$' , but it doesn't work.

Then I found out it is the problem of '?'.
Becuase I tried to match /aaa?aaa using r'aaa\?aaa' r'aaa\\?aaa' even r'aaa.*aaa' , all failed, but it works when it's "+" or any other character.
How to match the '?', is it special?

Answer 1

>>> s="aaa?aaa"
>>> import re
>>> re.findall(r'aaa\?aaa', s)
['aaa?aaa']

The reason /aaa?aaa won't match inside your URL is because a ? begins a new GET query.

So, the matchable part of the URL is only up to the first 'aaa'. The remaining '?aaa' is a new query string separated by the '?' mark, containing a variable "aaa" being passed as a GET parameter.

What you can do here is encode the variable before it makes its way into the URL. The encoded form of ? is %3F.

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You should also not match a GET query such as /?code=authenticationcode using regex at all. Instead, match your URL up to / using r'^$'. Django will pass the variable code as a GET parameter to the request object, which you can obtain in your view using request.GET.get('code').