jq find the max in quoted values

Question

Here is my JSON test.jsonfile :

[
  {
    "name": "nodejs",
    "version": "0.1.21",
    "apiVersion": "v1"
  },
  {
    "name": "nodejs",
    "version": "0.1.20",
    "apiVersion": "v1"
  },
  {
    "name": "nodejs",
    "version": "0.1.11",
    "apiVersion": "v1"
  },
  {
    "name": "nodejs",
    "version": "0.1.9",
    "apiVersion": "v1"
  },
  {
    "name": "nodejs",
    "version": "0.1.8",
    "apiVersion": "v1"
  }
]

When I use max_by, jq return 0.1.9 instead of 0.1.21 probably due to the quoted value :

cat test.json | jq 'max_by(.version)'
{
  "name": "nodejs",
  "version": "0.1.9",
  "apiVersion": "v1"
}

How can I get the element with version=0.1.21 ?

Answer 1

Semantic version compare is not supported out of the box in jq. You need to play around with the fields split by .

jq 'sort_by(.version | split(".") | map(tonumber))[-1]'

The split(".") takes the string from .version and creates an array of fields i.e. 0.1.21 becomes an array of [ "0", "1", "21"] and map(tonumber) takes an input array and transforms the string elements to an array of digits.

The sort_by() function does a index wise comparison for each of the elements in the array generated from last step and sorts in the ascending order with the object containing the version 0.1.21 at the last. The notation [-1] is to get the last object from this sorted array.