POST DATA in cache_key

[fiyah2011]

is it possible to use a value found within POST DATA as part of the
cache key?

for example, the value of variable called 'username' to be part of the
cache key.

so i basically want the cache to key to simply hash against the
connecting IP and the 'username' POST variable.

proxy_cache_key "$remote_addr$POST[username]"

thanks in advance

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,224945,224945#msg-224945