Modifying nested json conditionally using jq

Question

I would like to modify something like the following JSON:

{
  "foobar": {
    "a": {
      "adkjfe": {
        "A": 1,
        "foo": "bar"
      }
    },
    "b": {
      "ekjaei": {
        "A": 2,
        "bar": "foo"
      }
    }
  }
}

to add more data say {"baz": ["bing", "bop"]} to the parent of A if A=1. Assuming I don't know the parent key while leaving the rest of the json untouched. I've tried many different things including:

.foobar | .. | .. | .[] | if select(.A==1) then . += {"baz": "bing"} else . end

which gives me an error and only my modified section.

The result, in this case, that I would like to see is:

{
  "foobar": {
    "a": {
      "adkjfe": {
        "A": 1,
        "foo": "bar",
        "baz": ["bing", "bop"]
      }
    },
    "b": {
      "ekjaei": {
        "A": 2,
        "bar": "foo"
      }
    }
  }
}

Bertrand Martel · Accepted Answer · 2016-12-28 21:30:47Z

5

Select only fields that are of type object and that match your condition (A == 1) :

jq '(.foobar | .. | select(type == "object" and .A == 1)) |= .+ {"baz": ["bing", "bop"]}' test.json

The () around the filter query take care that the whole document will be returned with the updated fields and not just your subdocument

answered Dec 28, 2016 at 21:30

Bertrand Martel

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2 Comments

dbarnett Over a year ago

Works like buttah! Thank you!

Ed Randall Over a year ago

it seems also possible to use | objects in place of type == "object" since jq 1.4 which may be more readable.

peak · Accepted Answer · 2016-12-29 15:03:01Z

4

In general it is better to avoid .. if possible, for reasons of efficiency. In the present case, the following will do the job:

(.foobar[][] | select(.A == 1)) |= .+ {"baz":["bing", "bop"]}

edited Dec 29, 2016 at 15:03

answered Dec 29, 2016 at 8:10

peak

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1 Comment

Ed Randall Over a year ago

This works because each [] essentially moves down one object tree level, so this solution searches at a fixed 2-levels deep. (This has been a conceptual problem for me since my mind is conditioned to think 'array' when it sees []). And it's more efficient because the .. literally iterates every node right out to the leaf, which may be unnecessary, though probably unavoidable if the structure is more ragged.

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