Convert json single-item arrays to objects using bash/jq

Question

Given the example JSON below:

{
  "account_number": [
    "123456"
  ],
  "account_name": [
    "name"
  ],
  "account_id": [
    654321
  ],
  "username": [
    "demo"
  ]
}

I'd like to get:

{
  "account_number": "123456",
  "account_name": "name",
  "account_id": 654321,
  "username": "demo"
}

Currently, I'm brute forcing it with | sed 's/\[//g' | sed 's/\]//g' | jq '.' ... but of course, that's ugly and causes issues if any of the values contain [ or ].

I've been unsuccessful with jq's flatten and other loops and mapping techniques like | jq -s '{Item:.[]} | .Item |add' to try and flatten the single-item arrays. Ideally, it would work where it would flatten arrays [...] to flat elements/objects {...}. Either way something better than replacing all occurrences of square brackets.

peak · Accepted Answer · 2022-08-29 21:10:06Z

2

Short and sweet:

 map_values(first)

answered Aug 29, 2022 at 21:10

peak

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3 Comments

TryTryAgain Over a year ago

Love the most elegant, thanks for sharing.

pmf Over a year ago

Almost 50% shorter, yet nowhere near that elegance: .[]|=.[0] ☺

peak Over a year ago

If elegance is in the eye of the beholder, shortness must be in the eye of the metric.

choroba · Accepted Answer · 2022-08-29 20:50:39Z

1

Use with_entries, changing each value to the first element of itself:

jq 'with_entries(.value |= .[0])' file.json

edited Aug 29, 2022 at 20:50

answered Aug 29, 2022 at 20:48

choroba

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1 Comment

TryTryAgain Over a year ago

Super, that makes sense, I didn't even realize that. Live and learn, thank you!

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