jq · lesson 13 of 32 · Transforming

map & select together

map(f) runs f on every element and collects the results into a new array. Combine it with select to filter and transform in one step.

Example 1Names of the active members

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(select(.active) | .name)

map( Run the filter inside on every element and collect the results (map(f) is short for [.[] | f]).
select(.active) Drop inactive members — select may output nothing, and map simply collects fewer results.
| .name Keep just the name.

Result

["Ada","Linus","Alan"]

Try it in the playground

Good to know

map_values(f) is the object version: it updates every value and keeps the keys.