Add an index to an array of JSON objects with jq

jq_add_index.md

Add an index field to an array of objects

input data.json:

[
  {
    "foo": "bar"
  } ,
  {
    "foo": "baz"
  } ,
  {
    "foo": "dingo"
  }
]

cat data.json | jq 'to_entries | map({ "id": .key} + .value)'

output:

[
  {
    "id": 0 ,
    "foo": "bar"
  } ,
  {
    "id": 1 ,
    "foo": "baz"
  } ,
  {
    "id": 2 ,
    "foo": "dingo"
  }
]