Rate Limit by URL

Hi, I make this:

And it works, but I don’t want to rate limit the path (e.g. vanessamello.com**/img**)

I want to rate the entire URL.

I tried to change from:
http-request set-var(req.rate_limit) path,map_beg(/etc/haproxy/rates.map,20)

to:
http-request set-var(req.rate_limit) map_str(/etc/haproxy/rates.map,20)

But I have this output:

[ALERT] (243) : parsing [/etc/haproxy/haproxy.cfg:123] : error detected in frontend ‘www-h2-https’ while parsing ‘http-request set-var(req.rate_limit)’ rule : unknown fetch method ‘map_str’.
[ALERT] (243) : Error(s) found in configuration file : /etc/haproxy/haproxy.cfg
failed!

Please, do anybody have any tip?