negation in the map directive of nginx

[libresco_27]

Hi,

I'm working on rate limiting for specific group of client ids where if the
client id is equal to XYZ don't map it, thus, the zone doesn't get
incremented.

For ex - 
limit_req_zone $default_rate_client_id zone=globalClientRateLimit_zone:50k
rate=10r/m sync;
map $client_id $default_rate_client_id {
    "^(?!ZZZZZZ)$" "$1" 
} 

But this doesn't seem to work. Is this the correct way to negate a
particular string(ZZZZZ in this example)? Please let me know.

Thanks!

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,295157,295157#msg-295157