jq · lesson 16 of 32 · Transforming

Types & conversion

type names a value's type, and tostring, tonumber, tojson and fromjson convert between types.

Example 1Inspect and convert

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[0] | (.age | tostring), (.skills | type), ("42" | tonumber)

(.age | tostring) Number → string: "36".
(.skills | type) The type's name: "array".
("42" | tonumber) String → number: 42. Any literal can be piped into a filter.

Result

"36"
"array"
42

Try it in the playground

Good to know

The types are null, boolean, number, string, array and object.
Format strings re-encode a value: .name | @base64, @uri, @html, @sh, and @json (the same as tojson).