JMESPath · lesson 3 of 15 · Projections

Slices

[start:end:step] works like a Python slice: the end is exclusive, negative numbers count from the end, and every part is optional.

Example 1A range

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[1:3].name

[1:3] Elements 1 and 2 (the end is exclusive). A slice starts a projection, so the rest of the expression runs on each element.
.name Their names → ["Linus","Grace"].

Result

["Linus","Grace"]

Try it in the playground

Example 2Every other element

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[::2].name

[::2] Start and end left open, step 2: elements 0 and 2.

Result

["Ada","Grace"]

Try it in the playground

Good to know

members[-2:] is the last two elements.