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$lookup

$lookup(value?, key) -> value
Compact type signature<x-s:x>

If value is omitted, the current context value is used.

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Objects And Structure

Source: JSONata

Documentation​

Returns the value associated with key in object. If the first argument is an array of objects, then all of the objects in the array are searched, and the values associated with all occurrences of key are returned.

Examples​

Lookup a value by key name​

Input

This example uses the patient-summary example input. The expression selects the nested identifiers object and looks up one key by name.

Example input

JSON
{
  "patientId": "pat-0001",
  "name": {
    "given": "Avery",
    "family": "Reed",
    "display": "Avery Reed"
  },
  "birthDate": "1990-06-12",
  "sex": "female",
  "primaryCareTeam": {
    "organization": "ExampleCare",
    "facility": "ExampleCare Clinic",
    "practitioner": {
      "practitionerId": "prac-4001",
      "display": "Jordan Kim"
    }
  },
  "identifiers": {
    "memberId": "mbr-3001",
    "recordNumber": "rec-5001"
  },
  "tags": [
    "demo",
    "fictional"
  ],
  "_xmlTagName": "patientSummary"
}

Expression

$lookup(identifiers, "memberId")

Result

"mbr-3001"