map documentation could use some more information

[brucejo75]

Moved from https://github.com/caddyserver/caddy/issues/4642

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Did you know that the map directive cannot assign integers to placeholders? Unclear from the documentation. There is a lot of integer assignment in the example but if you assume the placeholder is an integer you would be wrong.

Luckily I ran across this forum entry.

Request: please update the documentation to explain that the map directive cannot assign integers.

Thanks!

[brucejo75]

BTW: let me know if you would like me to submit a PR. Happy to help!

[mholt]

The Caddyfile currently parses all values as strings. I suppose we could try to infer numbers and cast them before putting them into the map handler, but the map handler does in fact support numeric types if you use JSON.

I believe the only place the type of the map value would matter is in CEL expressions, not general Caddy usage.

[brucejo75]

That is a rather complicated specification. Maybe worth some more documentation? I am happy to take a shot at it if you like.

[mholt]

Well, I haven't tested it yet, but I pushed a quick fix here: caddyserver/caddy@93c99f6

It should now store numbers as numeric types (and booleans as booleans).

If you want to build from tip and test it out, that'd be splendid 😃

[francislavoie]

I had some ideas to make this nicer, and work "as expected" in more situations: caddyserver/caddy#4643.

I liked Matt's idea of casting to scalar types, but it felt like a hack by doing it inside of the directive's parsing, instead of the token dispenser. And Matt's implementation didn't handle "true" and "0" as a strings, it would cast those to boolean/int respectively too.

[mholt]

Since that PR is merged, this should be much more intuitive now, which I think is more correct. Thanks!

[brucejo75]

Wow! OK