FHIR Extension Helpers

Introduction

This is an unofficial set of helper functions to ease working with FHIR Extensions in Javascript and TypeScript.

This library provides for FHIR R4:

• getExtension & getExtensions
• setExtension & addExtension
• getExtesion[Value type]Value
• clearExtensions
• hasExtension, hasExtensionAny

IMPORTANT Once things settle in, it will be deployed to the public npm registry

Example Usage

Setting a specific extension value (complex datatype properties/elements) Note: Will remove any other extensions with this extension URL too.

import exHelpers from 'fhir-extension-helpers';

let sample = { system: 'system', code: 'c', display: 'blah' };
exHelpers.setExtension(sample, { url: 'https://example.org/exturl', valueBoolean: true });

Adding an extension (will append to the extensions, not replace existing one(s))

exHelpers.addExtension(sample, { url: 'https://example.org/exturl', valueString: "test" });

Retrieving a specific untyped extension value (as first only - no warning if there are multiple values)

let result = exHelpers.getExtension(sample, 'https://example.org/exturl');

Retrieving a specific typed extension value (as first only - no warning if there are multiple values)

let result = exHelpers.getExtensionStringValue(sample, 'https://example.org/exturl');

Retrieving the collection of untyped extension values

let result = exHelpers.getExtensions(sample, 'https://example.org/exturl');

Removing all extensions with a specific URL

exHelpers.clearExtension(sample, 'https://example.org/exturl');

Setting an extension on a primitive property

let patient = { resourceType: 'Patient', birthDate: '1974-12-25' };
exHelpers.setExtension(patient._birthDate, 
    {
        url: 'http://hl7.org/fhir/StructureDefinition/patient-birthTime', 
        valueDateTime: '1974-12-25T14:35:45-05:00'
    },
    () => { return patient._birthDate = {} });

Support

TBD - there's not really much here... For questions and broader discussions, use the FHIR Implementers chat on Zulip.

Contributing

I'm welcoming contributors from the FHIR community!