Override a set_empty variable from http params

[Igor Sysoev]

On Sun, Oct 14, 2012 at 11:30:22AM -0700, Quintin Par wrote:
> Hi all,
> 
> I set the some params to my backend server as shown below
> 
> set_if_empty $country_code $http_x_country_code;
> 
> proxy_set_header   X-Country-Code   $country_code;
> 
> Now the http_x_country_code comes via the GeoIP module.
> 
> Is there a way here I can override this based on an HTTP param I can set.
> 
> Say site.com/country=US and country variable has greater precedence over
> the http_x_country_code.

Using "map" you can define: 

http {

    map  $arg_country          $country_code {
         ""                    $header_country;
         default               $arg_country;
    }

    map  $http_x_country_code  $header_country {
         ""                    $geoip_country_code;
         default               $http_x_country_code;
    }

    ...

    location / {
        proxy_set_header  X-Country-Code   $country_code;
        ...


-- 
Igor Sysoev
http://nginx.com/support.html