parse_accept_lang_header parse HTTP_ACCEPT_LANGUAGE with wrong Quality factors

[flier.lu@…]

According to the RFC 2616 <​http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html>, HTTP_ACCEPT_LANGUAGE could have several languages options, such as

da, en-gb;q=0.8, en;q=0.7

So, django parse those string with parse_accept_lang_header method, and order the options base on its 'q' quality factor.

But the re.split seems return a list with a empty string as first element, such as

s = 'da, en-gb;q=0.8, en;q=0.7'

r.split(s)

[, 'da', None, , 'en-gb', '0.8', , 'en', '0.7', ]

But parse_accept_lang_header use it from index 0, it means they align to wrong index

To fix the issues, you could modify the accept_language_re, or use the return list from index 1.

def parse_accept_lang_header(lang_string):

"""
Parses the lang_string, which is the body of an HTTP Accept-Language
header, and returns a list of (lang, q-value), ordered by 'q' values.

Any format errors in lang_string results in an empty list being returned.
"""
result = []
pieces = accept_language_re.split(lang_string)
if pieces[-1]:

return []

for i in range(0, len(pieces) - 1, 3):

first, lang, priority = pieces[i : i + 3]
if first:

return []

priority = priority and float(priority) or 1.0
result.append((lang, priority))

result.sort(lambda x, y: -cmp(x[1], y[1]))
return result