jq · lesson 11 of 32 · Filtering & conditions

Testing text & arrays

test, startswith, endswith and contains return booleans, so they slot straight into select.

Example 1Names that start with A or G

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[] | select(.name | test("^[AG]")) | .name

select( Keep only members for which the test is true.
test("^[AG]") A regex match on the piped-in string: ^ anchors at the start and [AG] is one of the letters A or G.

Result

"Ada"
"Grace"
"Alan"

Try it in the playground

Example 2Members with a given skill

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[] | select(.skills | contains(["sql"])) | .name

select( Keep only members for which the test is true.
contains(["sql"]) True when the array includes every element of the argument — here the string "sql".

Result

"Ada"

Try it in the playground

Good to know

Also handy: startswith("A"), endswith(".com"), has("email") (does the key exist?) and any(.skills[]; . == "rust") (does some element satisfy the condition?).