Validate a code against a ValueSet

$validate-code checks whether a supplied code belongs to a ValueSet. It can also check an optional display string and return the preferred display for a valid concept.

Method	Path
GET or POST	/fhir/R4/ValueSet/$validate-code

At this type-level route, identify the ValueSet with url, context, or valueSet. Provide exactly one code input: code (with a code system), coding, or codeableConcept.

GET request

Pass the canonical ValueSet URL and code details as query parameters:

curl --get 'https://api.sandbox.ovok.com/fhir/R4/ValueSet/$validate-code' \
  --header "Authorization: Bearer ${OVOK_TOKEN}" \
  --data-urlencode 'url=https://example.org/fhir/ValueSet/vitals' \
  --data-urlencode 'system=http://loinc.org' \
  --data-urlencode 'code=8867-4' \
  --data-urlencode 'display=Heart rate'

POST request

For structured input, send a FHIR Parameters resource. This example supplies the ValueSet canonical URL and a Coding:

curl --request POST \
  --url 'https://api.sandbox.ovok.com/fhir/R4/ValueSet/$validate-code' \
  --header "Authorization: Bearer ${OVOK_TOKEN}" \
  --header 'Content-Type: application/fhir+json' \
  --data @validate-valueset-code-parameters.json

Example validate-valueset-code-parameters.json:

{
  "resourceType": "Parameters",
  "parameter": [
    {
      "name": "url",
      "valueUri": "https://example.org/fhir/ValueSet/vitals"
    },
    {
      "name": "coding",
      "valueCoding": {
        "system": "http://loinc.org",
        "code": "8867-4",
        "display": "Heart rate"
      }
    }
  ]
}

Successful response

The operation returns a FHIR Parameters resource.

Response path	Example	Meaning
resourceType	Parameters	FHIR wrapper for the operation output.
parameter[name=result].valueBoolean	true	Whether the supplied concept is valid in the ValueSet; false means it is not.
parameter[name=display].valueString	Heart rate	Preferred display string, when available.
parameter[name=message].valueString	Optional	Validation failure details, hint, or warning, when present.

If the ValueSet cannot be resolved or the request cannot be evaluated, the server can return an OperationOutcome with diagnostic details.

Reference: HL7 FHIR R4 ValueSet $validate-code.