FHIR Extension Data Type (R4)

Extension adds data that the base specification doesn't define. Element table, example JSON and FHIRPath for FHIR R4.

Overview

Extension adds data that the base specification doesn't define. Each has a url that identifies its definition and exactly one value[x] (or nested extensions). Modifier extensions use modifierExtension and change the meaning of the resource.

Elements

Element	Type	Cardinality	Description
Extension.url	String	1..1	identifies the meaning of the extension
Extension.value[x]	base64Binary \| boolean \| canonical \| code \| date \| dateTime \| decimal \| id \| instant \| integer \| markdown \| oid \| positiveInt \| string \| time \| unsignedInt \| uri \| url \| uuid \| Address \| Age \| Annotation \| Attachment \| CodeableConcept \| Coding \| ContactPoint \| Count \| Distance \| Duration \| HumanName \| Identifier \| Money \| Period \| Quantity \| Range \| Ratio \| Reference \| SampledData \| Signature \| Timing \| ContactDetail \| Contributor \| DataRequirement \| Expression \| ParameterDefinition \| RelatedArtifact \| TriggerDefinition \| UsageContext \| Dosage \| Meta	0..1	Value of extension

Example JSON (R4)

{
  "url": "http://hl7.org/fhir/StructureDefinition/patient-birthPlace",
  "valueAddress": {
    "city": "Boston",
    "state": "MA",
    "country": "US"
  }
}

FHIRPath

Patient.extension('http://hl7.org/fhir/StructureDefinition/patient-birthPlace').value — Read an extension's value

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