urlencode an array of values

The solution is far simpler than the ones listed above.

>>> import urllib
>>> params = {'criterias[]': ['member', 'issue']}
>>> 
>>> print urllib.urlencode(params, True)
criterias%5B%5D=member&criterias%5B%5D=issue

Note the True. See http://docs.python.org/library/urllib.html#urllib.urlencode the doseq variable.

As a side note, you do not need the [] for it to work as an array (which is why urllib does not include it). This means that you do not not need to add the [] to all your array keys.

You can use a list of key-value pairs (tuples):

>>> urllib.urlencode([('criterias[]', 'member'), ('criterias[]', 'issue')])
'criterias%5B%5D=member&criterias%5B%5D=issue'

To abstract this out to work for any parameter dictionary and convert it into a list of tuples:

import urllib

def url_encode_params(params={}):
    if not isinstance(params, dict): 
        raise Exception("You must pass in a dictionary!")
    params_list = []
    for k,v in params.items():
        if isinstance(v, list): params_list.extend([(k, x) for x in v])
        else: params_list.append((k, v))
    return urllib.urlencode(params_list)

Which should now work for both the above example as well as a dictionary with some strings and some arrays as values:

criterias = ['member', 'issue']
params = {
    'criterias[]': criterias,
}
url_encode_params(params)
>>'criterias%5B%5D=member&criterias%5B%5D=issue'