Regex Capture named groups should be null

[splitice]

A note for the community

• Please vote on this issue by adding a 👍 reaction to the original issue to help the community and maintainers prioritize this request
• If you are interested in working on this issue or have submitted a pull request, please leave a comment

Problem

Currently with parse_regex (and probably parse_regexes) an unmatched group matches as an empty string.

This is wasteful and creates problems should there be the need to match an empty capture vs not present capture (null)

Configuration

in VRL:
. = `parse_regex(.message, "^(abc: (?P<abc>[a-zA-Z]+))?")`

.abc will be "" on an empty or non matching .message

Version

0.26

Debug Output

-

Example Data

Additional Context

References

[jszwedko]

Hi @splitice ,

This doesn't seem to be the case in the latest version of Vector, I see:

$ .message = "no match"
"no match"

$ . = parse_regex!(.message, r'^(abc: (?P<abc>[a-zA-Z]+))?')
{ "abc": null }

Can you try upgrading and seeing if it resolves the issue for you?

[splitice]

@jszwedko You might be right, we are a bit behind. Thank you for your response, hopefully I didnt waste your time. I'll confirm with latest in the coming days.

I recall we had some performance regressions but I can't recall the specifics (probably metrics). I think thats why we never moved to 0.27.x (performance regression).

I'll certainly give a newer version a try and test again.

[jszwedko]

👍 sounds good. I'll close this out but feel free to reopen if it doesn't resolve the issue for you.