Rename args in nginx redirect

Question

I am trying to get an NGINX redirect to take me from:

https://example.com/ui/?outletID=123&setID=456

to:

https://example.com/ui/?outletId=123&setIds=456

So outletID -> outletId AND setID -> setIds

IMPORTANT: I don't know where these params appear inside the URL, so there might be other strings before or after these. I only care for this replacements: outletID -> outletId; setID -> setIds.

This works at first try:

if ($args ~* "^outletID=(\d+)&setID=(\d+)(.*)") {
    set $outletid $1;
    set $setid $2;
    set $everythingelse $3;
    set $args '';
    rewrite ^.*$ /ui/?outletId=$outletid&setIds=$setid$everythingelse permanent;
}

But it looks like really bad practice and I particularly hate the $everythingelse ($3) solution I ended up with.

Answer 1

To cover all possibilities, you probably need to do this in two stages, one redirect if outletID is present, and another redirect if setID is present.

For example:

if ($args ~ ^(.+&|)outletID(=.*)$) {
    return 301 "$uri?${1}outletId$2";
}
if ($args ~ ^(.+&|)setID(=.*)$) {
    return 301 "$uri?${1}setIds$2";
}