CODEWITHSUNDEEP
jsonjq
dolmen
dolmen

Reputation: 8706

Swap keys in nested objects using JQ

Using jq, how can I transform:

{ "a": {"b": 0}, "c": {"d": 1}}

into:

{"b": {"a": 0}, "d": {"c": 1}}

without knowing the name of the keys in the source?

(I know that this can lose data in the general case, but not with my data)

Upvotes: 1

Views: 334

Answers (3)

jq170727
jq170727

Reputation: 14715

Here is a solution which uses jq streams and variables:

[
  . as $d
| keys[]
| $d[.] as $v
| ($v|keys[]) as $vkeys
| {
    ($vkeys): {
       (.): ($vkeys|$v[.])
    }
  }
] | add

It is easy to lose track of what is what at the end so to see more clearly what's going on here is a slightly expanded version with additional comments and variables.

[
  . as $d                    # $d:     {"a":{"b":0},"c":{"d": 1}}
| keys[] | . as $k           # $k:     "a", "c"
| $d[$k] as $v               # $v:     {"b": 0}, {"d": 1}
| ($v|keys[]) as $vkeys      # $vkeys: "b", "d"
| ($vkeys|$v[.]) as $vv      # $vv:    0, 1
| {
    ($vkeys): {              # "b": {     "d": {
       ($k): $vv             #   "a": 0      "c": 1
    }                        # }        , }
  }
] | add

Upvotes: 0

peak
peak

Reputation: 116919

def swapper:
  . as $in
  | reduce keys[] as $key
      ( {}; . + ( $in[$key] as $o
                  | ($o|keys[0]) as $innerkey
                  | { ($innerkey): { ($key): $o[$innerkey] } } ) ) ;

Example:

{ "a": {"b": 0}, "c": {"d": 1}} | swapper

produces:

{"b":{"a":0},"d":{"c":1}}

Upvotes: 0

Jeff Mercado
Jeff Mercado

Reputation: 134571

Here's an alternative using with_entries:

with_entries(.key as $parent
  | (.value|keys[0]) as $child
  | {
        key: $child,
        value: { ($parent): .value[$child] }
    }
)

Upvotes: 1

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