Creating Array of Objects from Bash Array using jq

Question

I am trying to create an array of objects in bash given an array in bash using jq.

Here is where I am stuck:

IDS=("baf3eca8-c4bd-4590-bf1f-9b1515d521ba" "ef2fa922-2038-445c-9d32-8c1f23511fe4")
echo "${IDS[@]}" | jq -R '[{id: ., names: ["bob", "sally"]}]'

Results in:

[
   {
     "id": "baf3eca8-c4bd-4590-bf1f-9b1515d521ba ef2fa922-2038-445c-9d32-8c1f23511fe4",
     "names": [
       "bob",
       "sally"
     ]
   }
]

My desired result:

[
   {
     "id": "baf3eca8-c4bd-4590-bf1f-9b1515d521ba",
     "names": [
       "bob",
       "sally"
     ]
   },
   {
     "id": "ef2fa922-2038-445c-9d32-8c1f23511fe4",
     "names": [
       "bob",
       "sally"
     ]
   }
]

Any help would be much appreciated.

pmf · Accepted Answer · 2021-11-05 12:50:28Z

5

Split your bash array into NUL-delimited items using printf '%s\0', then read the raw stream using -R or --raw-input and within your jq filter split them into an array using split and the delimiter "\u0000":

printf '%s\0' "${IDS[@]}" | jq -Rs '
  split("\u0000") | map({id:., names: ["bob", "sally"]})
'

edited Nov 5, 2021 at 12:50

answered Nov 5, 2021 at 1:16

pmf

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6 Comments

dan Over a year ago

What is the purpose of null in this context?

Gordon Davisson Over a year ago

@dan null cannot occur in C-strings, or anything that mimics them; therefore, they tend to be safe to use as delimiters. (As opposed to spaces, newlines, etc which sometimes do occur in the middle of normalish strings.) In this case, it looks like the strings are pretty plain, so newlines are probably safe enough, but that's not always true.

dan Over a year ago

@GordonDavisson That’s true, however I tried this example with a bash array that had a multiline element, and everything was still split on new lines. With the accepted answer, it was split in to objects ({ }), and using nulls it was split in to arrays ([ ]).

pmf Over a year ago

@dan Can you provide your "bash array that had a multiline element" and how you created it?

pmf Over a year ago

@dan You are right, I forgot to --slurp the input. Fixed it.

|

peak · Accepted Answer · 2021-11-05 01:20:01Z

2

for id in "${IDS[@]}" ; do
  echo "$id"
done | jq -nR '[ {id: inputs, names: ["bob", "sally"]} ]'

or as a one-liner:

printf "%s\n" "${IDS[@]}" | jq -nR '[{id: inputs, names: ["bob", "sally"]}]'

answered Nov 5, 2021 at 1:20

peak

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