affiliates_service_affiliate_id_from_url

add_filter ( 'affiliates_service_affiliate_id', 'affiliates_service_affiliate_id_from_url', 10, 2 );

function affiliates_service_affiliate_id_from_url ( $affiliate_id, $service )  {
    global $wp, $wpdb;

    $pname = get_option( 'aff_pname', AFFILIATES_PNAME );
    $affiliate_id = isset( $_GET[$pname] ) ? affiliates_check_affiliate_id_encoded( trim( $_GET[$pname] ) ) : $affiliate_id;

    if ( isset( $_GET[$pname] ) ) {
        // affiliates-by-username uses this hook
        $maybe_affiliate_id = apply_filters( 'affiliates_parse_request_affiliate_id', $_GET[$pname], $affiliate_id );
        if ( ( $maybe_affiliate_id !== null ) && $maybe_affiliate_id !== trim( $_GET[$pname] ) ) {
            $affiliate_id = $maybe_affiliate_id;
        }
    }
    return $affiliate_id;
}