[issue13866] {urllib, urllib.parse}.urlencode should not use quote_plus
Stephen Day stevv...@gmail.com added the comment:
While it's likely that adding a `quote`/`quote_plus` function paramater to
urlencode is the right solution, I want to ensure that the key point is
communicated clearly: encoding a space as a '+' is pathological, in that in the
common case, an unescaped encoded character is indistinguishable from a literal
'+'. Take the case of the literal string '+ '. If one uses the javascript
encodeURI function to encode the string in a browser console, one gets the
following:
encodeURI('+ ')
+%20
Now, we have a string that will not decode symmetrically. In other words, we
cannot tell if this string should decode to ' ' or '+ '. And while use of
encodeURI is discouraged, application developers still use it places,
introducing these kinds of errors.
Conversely, we can see that the behavior of encodeURIComponent, is unambiguous:
encodeURIComponent('+ ')
%2B%20
And while these are analogues to quote and quote_plus (there exists now
analogue to javascripts urlencode), it's easy to see that disambiguating the
encoding of the resulting output of urlencode would be desirable.
There is a similar situation with php library functions.
Furthermore, it is agreed that urlencode does follow the rules, but the rules,
as they are, introduce an asymmetrical, pathological encoding. Most services
accept '%20' as space in lieu of '+' when data is encoded as
'application/x-www-form-urlencoded' anyway.
Concluding, I know it seems a little silly to spend time filing this bug and
provide relevant cases, but I'd like to cite professional experience in this
matter; I have seen pluses-for-spaces introduce errors time and time again.
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[issue13866] {urllib, urllib.parse}.urlencode should not use quote_plus
Stephen Day stevv...@gmail.com added the comment:
I apologize for reopening this bug, but I find your interpretation to be
inaccurate. While technically valid, the combination of the documentation, the
function name and the main use cases yields pathological invocations of
urlencode. My bug report is to help mitigate these problems.
The main use case for url encoding of mapping types is not for posting form
data; the main use case is appending url parameters to a url:
from urllib import urlencode
from urlparse import urlunparse
urlunparse(('http', 'example.com', '/', None, urlencode({'a': 'some
string'}), None))
'http://example.com/?a=some+string'
Any sane person would naturally gravitate to a function called urlencode to
url encode a mapping type. If the urllib.urlencode function is indeed intended
for form-encoding, as I agree is hinted in the documentation, it should
indicate that its result is 'application/x-www-form-urlencoded' or it should be
called formencode.
The quote or quote_plus is not at all what I am looking for; I am quite
familiar with these library functions. These functions are for encoding
component strings; they don't meet the use case described at all:
quote({'a': 1})
Traceback (most recent call last):
File stdin, line 1, in module
File
/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/urllib.py,
line 1248, in quote
if not s.rstrip(safe):
AttributeError: 'dict' object has no attribute 'rstrip'
In addition, Java's URLEncoder implementation is hardly a good example of
standards compliant URL manipulation. Python is not Java. The Python community
needs to make its own, independent, mature language decisions. In general, the
use of '+' to encode spaces in content, even if it is compliant against an
arbitrary standard, is pathological, especially when used in urls. Even though
python's quote_plus function works symmetrically on its own, when pluses are
used in a multi-language environment it can become impossible to tell whether a
plus is a literal '+' or an encoded space. In addition, the usage of '%20' for
spaces will work in almost all cases.
RFC3986, Section 2 [1] describes the use of percent-encoding as a solution to
representing reserved characters. In practice, percent-encoding is used on the
value component of 'key=value' productions and this works in nearly all cases.
The referenced standard [2], while relevant to the implied use case, is not
applicable to url assembly.
Given your interpretation, it seems that there is no function in the python
standard library to meet the use case of correctly assembling url parameter
values, leaving application developers to come up with something like this:
''.join(['='.join((quote(k), quote(v))) for k,v in {'a': '1', 'b': 'with
spaces'}.iteritems()])
'a=1b=with%20spaces'
In most cases, people will just use urlencode, which uses pluses for spaces,
yielding pathological, noncompliant urls.
In deference to this bug closure, there are a few options:
1. Close this issue and keep polluting the world's urls with pluses for spaces.
2. Make urlencode target path/query parameter encoding and then create a new
function, formencode, for use in encoding form data, breaking backwards
compatibility.
3. Simply add a keyword argument to urlencode to allow the caller to specify
the encoding function and separator, retaining compatibility and satisfying all
of the above use cases.
Naturally, 3 seems to be a very reasonable solution to this bug.
[1] http://tools.ietf.org/html/rfc3986#section-2 explicitly covers
[2] http://www.w3.org/TR/html4/interact/forms.html#h-17.13.4.1
--
resolution: invalid -
status: closed - open
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[issue13866] {urllib, urllib.parse}.urlencode should not use quote_plus
New submission from Stephen Day stevv...@gmail.com:
The current behavior of the urlencode function (2.7: urllib, 3.x: urllib.parse)
encodes spaces as pluses:
from urllib import urlencode
urlencode({'a': 'some param'})
'a=some+param'
However, in most instances, it would be desirable to merely encode spaces using
percent encoding:
urlencode({'a': 'some param'})
'a=some%20param'
But there is no way to get this behavior in the standard library.
It would probably best to change this so it defaults to use the regular quote
function, but allows callers who need the legacy quote_plus behavior to pass
that in as a function parameter.
An acceptable fix would be to have the quote function taken as a keyword
parameter, so legacy behavior remains:
urlencode({'a': 'some param'})
'a=some+param'
Then the behavior could be adjusted where needed:
from urllib import quote
urlencode({'a': 'some param'}, quote=quote)
'a=some%20param'
--
components: Library (Lib)
messages: 151980
nosy: Stephen.Day
priority: normal
severity: normal
status: open
title: {urllib,urllib.parse}.urlencode should not use quote_plus
versions: Python 2.7, Python 3.1, Python 3.2, Python 3.3, Python 3.4
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[issue5183] wsgiref.simple_server not working
New submission from Stephen Day stephen.h@gmail.com:
The attached application doesn't work. I think the value of self.headers
(see line 114) has a blank line at the end that it did not in Python 2.5
Here is the error message that occurs when it gets a request
(http://127.0.0.1:8080/):
Exception happened during processing of request from ('127.0.0.1',
60549)
Traceback (most recent call last):
File C:\Python30\lib\socketserver.py, line 281, in
_handle_request_noblock
self.process_request(request, client_address)
File C:\Python30\lib\socketserver.py, line 307, in process_request
self.finish_request(request, client_address)
File C:\Python30\lib\socketserver.py, line 320, in finish_request
self.RequestHandlerClass(request, client_address, self)
File C:\Python30\lib\socketserver.py, line 614, in __init__
self.handle()
File C:\Python30\lib\wsgiref\simple_server.py, line 136, in handle
self.rfile, self.wfile, self.get_stderr(), self.get_environ()
File C:\Python30\lib\wsgiref\simple_server.py, line 115, in
get_environ
k,v = h.split(':',1)
ValueError: need more than 1 value to unpack
--
components: Library (Lib)
files: test_server.py
messages: 81366
nosy: StephenDay
severity: normal
status: open
title: wsgiref.simple_server not working
type: crash
versions: Python 3.0
Added file: http://bugs.python.org/file12976/test_server.py
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[issue5183] wsgiref.simple_server not working
Stephen Day stephen.h@gmail.com added the comment: This seems to be fixed already (see Issue4718). Next time I'll search more... ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5183 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
