[Web-SIG] Multiple message-header fields handling
alex at puddlejumper.foxybanana.com
Tue Oct 2 21:50:21 CEST 2007
On Tue, Oct 02, 2007 at 09:30:46PM +0200, Manlio Perillo wrote:
> The HTTP 1.1 protocol (section 4.2) says that:
> """Multiple message-header fields with the same field-name MAY be
> present in a message if and only if the entire field-value for that
> header field is defined as a comma-separated list [i.e., #(values)]."""
> This can happen, as an example, with the Cookie header.
> My question is: how should this be handled in WSGI?
> As an example Nginx stores all the headers in a associative array,
> where, of course, only the "last seen" headers appears.
> However common multiple message-headers are stored in the request struct.
Initially I used such a solution (cookies was a special property in the response
object), but I ended up just throwing together a custom dict that looks like:
def __setitem__(self, item, val):
if item in self:
iv = self[item]
if isinstance(iv, list):
iv = [iv, val]
dict.__setitem__(self, item, iv)
dict.__setitem__(self, item, val)
def replace(self, key, val):
dict.__setitem__(self, key, val)
ret = 
for k,v in dict.items(self):
if isinstance(v, list):
ret.extend([ (k, a) for a in v ])
It's really intended for passing the headers on to start_response, and for
getting the headers into it, rather then for reading from it, which is fine
99% of the time. I recently had to add replace since i had a situation where
I needed to overwrite a preset header, but other than that it serves me well.
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