jq · lesson 6 of 32 · Pipes & building output

Building objects

{ … } builds a new object. {name} is shorthand for {name: .name}, and a value can be any expression — wrap computed ones in parentheses.

Example 1Reshape each member

Document

{
  "team": "Platform",
  "office": { "city": "Berlin", "floor": 3 },
  "members": [
    { "name": "Ada", "age": 36, "role": "lead", "active": true,
      "email": "[email protected]", "skills": ["rust", "sql"] },
    { "name": "Linus", "age": 28, "role": "dev", "active": true,
      "email": null, "skills": ["c", "shell"] },
    { "name": "Grace", "age": 45, "role": "dev", "active": false,
      "skills": ["cobol"] },
    { "name": "Alan", "age": 41, "role": "qa", "active": true,
      "email": "[email protected]", "skills": [] }
  ]
}

Query

.members[] | {name, next_age: (.age + 1)}

{name Shorthand: copy the key name and its value from the input (same as name: .name).
next_age A brand-new key…
(.age + 1) …whose value is any expression, run against each member. The parentheses group it.

Result

{"name":"Ada","next_age":37}
{"name":"Linus","next_age":29}
{"name":"Grace","next_age":46}
{"name":"Alan","next_age":42}

Try it in the playground

Example 2Use a value as a key

Document

{
  "team": "Platform",
  "office": { "city": "Berlin", "floor": 3 },
  "members": [
    { "name": "Ada", "age": 36, "role": "lead", "active": true,
      "email": "[email protected]", "skills": ["rust", "sql"] },
    { "name": "Linus", "age": 28, "role": "dev", "active": true,
      "email": null, "skills": ["c", "shell"] },
    { "name": "Grace", "age": 45, "role": "dev", "active": false,
      "skills": ["cobol"] },
    { "name": "Alan", "age": 41, "role": "qa", "active": true,
      "email": "[email protected]", "skills": [] }
  ]
}

Query

.members | map({(.name): .age}) | add

map( Run the filter inside on every element and collect the results in an array.
{(.name): .age} A computed key: the parentheses make .name an expression, so each member becomes a one-key object.
| add Merge the array of small objects into one lookup table.

Result

{"Ada":36,"Linus":28,"Grace":45,"Alan":41}

Try it in the playground