Adding a new JSON key from an existing JSON value

Question

I have the following JSON;

[
  {
    "id": 1,
    "start": "2022-06-20",
    "result": 24
  },
  {
    "id": 2,
    "start": "2022-06-21",
    "result": 56
  },
  {
    "id": 3,
    "start": "2022-06-21",
    "result": 78
  }
]

I'm wanting to add 2 new values to each array above using JQ, dimension and date, but date needs to be a copy of the existing key value start. The expected output is as below;

[
  {
    "id": 1,
    "start": "2022-06-20",
    "result": 24,
    "date": "2022-06-20",
    "dimension": "new"
  },
  {
    "id": 2,
    "start": "2022-06-21",
    "result": 56,
    "date": "2022-06-21",
    "dimension": "new"
  },
  {
    "id": 3,
    "start": "2022-06-21",
    "result": 78,
    "date": "2022-06-21",
    "dimension": "new"
  }
]

The jq I have at present can add the new key dimension, but I can't figure out how to copy start -> date

jq '.[] += {"dimension": "new"}' input.json

Thanks for any help

ikegami · Accepted Answer · 2022-06-21 16:57:11Z

4

Just create the new key / value pairs.

jq 'map(.date = .start | .dimension = "new")' input.json

edited Jun 21, 2022 at 16:57

ikegami

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answered Jun 21, 2022 at 16:09

Arie

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1 Comment

ikegami Over a year ago

@Inian, sh makes more sense than none.

ikegami · Accepted Answer · 2022-06-21 17:01:38Z

1

You might have tried the following:

.[] += { date: .start, dimension: "new" }    // WRONG

But it's not quite right since . is the array, not the element of the array. You can use |= as a topicalizer.

.[] |= ( . += { date: .start, dimension: "new" } )

But I'd use map instead.

map( . += { date: .start, dimension: "new" } )

Alternatively,

. += { date: .start, dimension: "new" }

can also also be achieved using

.date = .start | .dimension: "new"

So you could use

.[] |= ( .date = .start | .dimension: "new" )

or

map( .date = .start | .dimension = "new" )

edited Jun 21, 2022 at 17:01

answered Jun 21, 2022 at 16:55

ikegami

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