jq: filter array and project other field

Here my document:

[
  {
    "id": "9f0e27fe-3b8f-4857-8e1d-e57e7a3f4c31",
    "identifier": [
      {
        "system": {
          "value": "urn:oid:1.3.6.1.4.1.19126.3"
        },
        "value": {
          "value": "Y3454867M"
        }
      },
      {
        "system": {
          "value": "urn:oid:2.16.724.4.9.10.2"
        },
        "value": {
          "value": "108505134"
        }
      }
    ]
  }
]

I need to pick only .identifier[where .system.value == "urn:oid:1.3.6.1.4.1.19126.3"] and project .identifier.value.value.

Desired output:

[
  {
    "id": "9f0e27fe-3b8f-4857-8e1d-e57e7a3f4c31",
    "identifier": "Y3454867M"
  }
]

I’ve been playing with map and select but I don’t quite figure out what’s the right way to get it.

Any ideas?

>Solution :

This approach uses first to get the first result, in case there is more than one array item matching the criteria.

jq --arg v "urn:oid:1.3.6.1.4.1.19126.3" '
  map(.identifier |= first(.[] | select(.system.value == $v).value.value))
'

[
  {
    "id": "9f0e27fe-3b8f-4857-8e1d-e57e7a3f4c31",
    "identifier": "Y3454867M"
  }
]

Demo