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$exists

$exists(value) -> boolean
Compact type signature<x:b>
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Logical Checks

Source: JSONata

Documentation​

Returns Boolean true if the arg expression evaluates to a value, or false if the expression does not match anything (e.g. a path to a non-existent field or an undefined value).

Examples​

Check whether an optional field is present​

Input

This example uses the patient-summary example input. The expression checks whether the referenced nested paths are present.

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

{
  "hasMemberId": $exists(identifiers.memberId),
  "hasPractitionerPhone": $exists(primaryCareTeam.practitioner.phone)
}

Result

{
  "hasMemberId": true,
  "hasPractitionerPhone": false
}