JMESPath · lesson 9 of 15 · Filtering

Functions in filters

Any function can appear in a condition, which is how you test text and arrays.

Example 1Does an array contain a value?

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[?contains(skills, 'sql')].name

contains(skills, 'sql') True when the array skills includes the string 'sql' (on a string, contains looks for a substring).

Result

["Ada"]

Try it in the playground

Example 2How many items?

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[?length(skills) > `1`].name

length(skills) The number of elements in skills.
> `1` …compared with the number 1: members with two or more skills.

Result

["Ada","Linus"]

Try it in the playground

Good to know

Functions are strict about types: ends_with(email, '.com') raises an error for Linus, whose e-mail is null. Guard it with type(email) == 'string' && ends_with(email, '.com').