parse_qsl fails on empty query argument without = #64150

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1. DavidPizzuto commented on Dec 11, 2013

   

   DavidPizzutomannequin

   on Dec 11, 2013

   MannequinAuthor

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   Using an empty query argument with no = fails in urlparse.parse_qsl. Chrome and Firefox accept it without the =, so a navigation to google.com/search?q=foo&bar appears in the address bar as google.com/search?q=foo&bar=. Neither RFC 1738 nor RFC 3986 define the format of query strings. Wikipedia is similarly silent.

   I can reproduce in 2.7.3 and 3.2.3, as shown below. I'm told this is also true of 3.3 but don't have easy access to a 3.3 interpreter to confirm.

   The obvious workaround is to simply set strict_parsing=False, but I don't know what other checks that's disabling. Would it be reasonable to change parse_qsl to add the = if it's not present?

   $ python
   Python 2.7.3 (default, Sep 26 2013, 20:03:06) 
   [GCC 4.6.3] on linux2
   Type "help", "copyright", "credits" or "license" for more information.
   >>> import urlparse
   >>> query = 'foo&bar=baz'
   >>> urlparse.parse_qs(query, strict_parsing=True, keep_blank_values=True)
   Traceback (most recent call last):
     File "<stdin>", line 1, in <module>
     File "/usr/lib/python2.7/urlparse.py", line 353, in parse_qs
       for name, value in parse_qsl(qs, keep_blank_values, strict_parsing):
     File "/usr/lib/python2.7/urlparse.py", line 387, in parse_qsl
       raise ValueError, "bad query field: %r" % (name_value,)
   ValueError: bad query field: 'foo'
   
   $ python3
   Python 3.2.3 (default, Sep 25 2013, 18:22:43) 
   [GCC 4.6.3] on linux2
   Type "help", "copyright", "credits" or "license" for more information.
   >>> import urllib.parse
   >>> query = 'foo&bar=baz'
   >>> urllib.parse.parse_qs(query, strict_parsing=True, keep_blank_values=True)
   Traceback (most recent call last):
     File "<stdin>", line 1, in <module>
     File "/usr/lib/python3.2/urllib/parse.py", line 556, in parse_qs
       encoding=encoding, errors=errors)
     File "/usr/lib/python3.2/urllib/parse.py", line 596, in parse_qsl
       raise ValueError("bad query field: %r" % (name_value,))
   ValueError: bad query field: 'foo'
2. bitdancer commented on Dec 11, 2013

   

   bitdancer

   on Dec 11, 2013

   Member

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   I did some research on this for a previous issue, and every description of query strings I could find agreed that the format was '<name>=<value>'. That is, that the '=' is not optional, even though some servers (note, *not* browsers, they just transmit or display the URI provided by the user or server) will accept parameters without the '=' and treat them as if they had one.

   So I think this being rejected by strict_parsing is correct. I'm closing this as invalid.

   As for what strict_parsing, controls, you can check the source. It looks like this and empty arguments (ie: &&) are the only things it controls.
3. bitdancer

   closed this as completedon Dec 11, 2013
4. bitdancer

   added

   invalid

   type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

   on Dec 11, 2013
5. ezio-melotti

   transferred this issue fromon Apr 10, 2022