Hi Mart I haven't really followed this thread closely, so I apologize if some of my comments below have already been addressed. Mart Sõmermaa wrote:
The general consensus in python-ideas is that the following is needed, so I bring it to python-dev to final discussions before I file a feature request in bugs.python.org <http://bugs.python.org>.
Proposal: add add_query_params() for appending query parameters to an URL to urllib.parse and urlparse.
Implementation: http://github.com/mrts/qparams/blob/83d1ec287ec10934b5e637455819cf796b1b421c... (feel free to fork and comment).
Behaviour (longish, guided by "simple things are simiple, complex things possible"):
In the simplest form, parameters can be passed via keyword arguments:
>>> add_query_params('foo', bar='baz') 'foo?bar=baz'
>>> add_query_params('http://example.com/a/b/c?a=b', b='d') 'http://example.com/a/b/c?a=b&b=d <http://example.com/a/b/c?a=b&b=d>'
Note that '/', if given in arguments, is encoded:
>>> add_query_params('http://example.com/a/b/c?a=b', b='d', foo='/bar') 'http://example.com/a/b/c?a=b&b=d&foo=%2Fbar <http://example.com/a/b/c?a=b&b=d&foo=%2Fbar>'
Duplicates are discarded:
Why discard duplicates? They are valid and have a well-defined meaning.
>>> add_query_params('http://example.com/a/b/c?a=b', a='b') 'http://example.com/a/b/c?a=b'
I would prefer: 'http://example.com/a/b/c?a=b&a=b'
>>> add_query_params('http://example.com/a/b/c?a=b&c=q <http://example.com/a/b/c?a=b&c=q>', a='b', b='d', ... c='q') 'http://example.com/a/b/c?a=b&c=q&b=d <http://example.com/a/b/c?a=b&c=q&b=d>'
I would prefer: 'http://example.com/a/b/c?a=b&c=q&a=b&b=d'
But different values for the same key are supported:
>>> add_query_params('http://example.com/a/b/c?a=b', a='c', b='d') 'http://example.com/a/b/c?a=b&a=c&b=d <http://example.com/a/b/c?a=b&a=c&b=d>'
Pass different values for a single key in a list (again, duplicates are removed):
>>> add_query_params('http://example.com/a/b/c?a=b', a=('q', 'b', 'c'), ... b='d') 'http://example.com/a/b/c?a=b&a=q&a=c&b=d <http://example.com/a/b/c?a=b&a=q&a=c&b=d>'
Keys with no value are respected, pass ``None`` to create one:
>>> add_query_params('http://example.com/a/b/c?a', b=None) 'http://example.com/a/b/c?a&b <http://example.com/a/b/c?a&b>'
But if a value is given, the empty key is considered a duplicate (i.e. the case of a&a=b is considered nonsensical):
Again, it is a valid url and this will change its meaning. Why?
>>> add_query_params('http://example.com/a/b/c?a', a='b', c=None) 'http://example.com/a/b/c?a=b&c <http://example.com/a/b/c?a=b&c>'
If you need to pass in key names that are not allowed in keyword arguments, pass them via a dictionary in second argument:
>>> add_query_params('foo', {"+'|äüö": 'bar'}) 'foo?%2B%27%7C%C3%A4%C3%BC%C3%B6=bar'
Order of original parameters is retained, although similar keys are grouped together.
Why the grouping? Is it a side effect of your desire to discard duplicates? Changing the order like that changes the meaning of the url. A concrete case where the order of field names matters is the ":records" converter in http://pypi.python.org/pypi/zope.httpform/1.0.1 (a small independent package extracted from the form handling code in zope).
Order of keyword arguments is not (and can not be) retained:
>>> add_query_params('foo?a=b&b=c&a=b&a=d', a='b') 'foo?a=b&a=d&b=c'
>>> add_query_params('http://example.com/a/b/c?a=b&q=c&e=d <http://example.com/a/b/c?a=b&q=c&e=d>', ... x='y', e=1, o=2) 'http://example.com/a/b/c?a=b&q=c&e=d&e=1&x=y&o=2 <http://example.com/a/b/c?a=b&q=c&e=d&e=1&x=y&o=2>'
If you need to retain the order of the added parameters, use an :class:`OrderedDict` as the second argument (*params_dict*):
>>> from collections import OrderedDict >>> od = OrderedDict() >>> od['xavier'] = 1 >>> od['abacus'] = 2 >>> od['janus'] = 3 >>> add_query_params('http://example.com/a/b/c?a=b', od) 'http://example.com/a/b/c?a=b&xavier=1&abacus=2&janus=3 <http://example.com/a/b/c?a=b&xavier=1&abacus=2&janus=3>'
If both *params_dict* and keyword arguments are provided, values from the former are used before the latter:
>>> add_query_params('http://example.com/a/b/c?a=b', od, xavier=1.1, ... zorg='a', alpha='b', watt='c', borg='d')
'http://example.com/a/b/c?a=b&xavier=1&xavier=1.1&abacus=2&janus=3&zorg=a&borg=d&watt=c&alpha=b <http://example.com/a/b/c?a=b&xavier=1&xavier=1.1&abacus=2&janus=3&zorg=a&borg=d&watt=c&alpha=b>'
Do nothing with a single argument:
>>> add_query_params('a') 'a'
>>> add_query_params('arbitrary strange stuff?öäüõ*()+-=42') 'arbitrary strange stuff?\xc3\xb6\xc3\xa4\xc3\xbc\xc3\xb5*()+-=42'
If you change it to keep duplicates and not unnecessarily mangle the field order I am +1, else I am -0. - Jacob