String substitution on array of strings

Question

I am trying to strip a substring from an array of strings; this array is obtained as a key set from a map. Some example incoming data:

{
  "appOneVersion": "1.0",
  "appTwoVersion": "1.0",
  "appThreeVersion": "1.0"
}

First I'm extracting the key set and making lower case which works:

 $ jq -r 'with_entries( .key |= ascii_downcase) | keys' example.json
[
  "apponeversion",
  "appthreeversion",
  "apptwoversion"
]

and then I'm attempting to strip the version part of each element with sub("version$"; "") however I'm not quite understanding how to make it iterate over the array instead of sub trying to operate on the array as a whole:

$ jq -r 'with_entries( .key |= ascii_downcase) | keys | sub("version$"; "")' example.json
jq: error (at example.json:5): array (["apponever...) cannot be matched, as it is not a string

I am trying to get all the keys; @peak below gave some options that work for me. — Friedrich 'Fred' Clausen
– Friedrich 'Fred' Clausen, Commented Aug 18, 2021 at 2:12

peak · Accepted Answer · 2021-08-18 01:32:56Z

1

It looks like map would do the trick, and you might also consider keys_unsorted:

with_entries( .key |= ascii_downcase )
| keys_unsorted | map(sub("version$"; ""))

Of course, there are other approaches....

If you wanted to retain the original structure:

with_entries( .key |= (ascii_downcase | sub("version$";"")))

answered Aug 18, 2021 at 1:32

peak

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Friedrich 'Fred' Clausen Over a year ago

Thanks, the original structure is not important so either will be fine. As with jq there probably are other approaches but this looks good for me.

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