Output the results of select operation in an array - jq

Question

I have the following input:

[
  {"id": "first", "val": 1}, 
  {"id": "second", "val": 2}, 
  {"id": "second", "val": 3}
]

Using the jq filter : .[] | select(.id == "second")

I get following as output :

 {
  "id": "second",
  "val": 2
 }
 {
  "id": "second",
  "val": 3
 }

I want to get the result in the form of an array. Is it possible to get the multiple result values of select operation in an array?

Answer 1

Yes; wrap the filter in an array :)

$ jq '[.[] | select(.id == "second")]' tmp.json
[
  {
    "id": "second",
    "val": 2
  },
  {
    "id": "second",
    "val": 3
  }
]

Or, use map/1, which is predefined as [.[] | ...].

$ jq 'map(select(.id == "second"))' tmp.json
[same result]

---

To wrap the results in a bash array, use the -c option to output each result on a single line, and read the result with readarray.

$ readarray -t arr < <(jq -c '.[] | select(.id == "second")' tmp.json)
$ for r in "${arr[@]}"; do echo "Result: $r"; done
Result: {"id":"second","val":2}
Result: {"id":"second","val":3}