FHIR Transform Package

Performs FHIR $transform operations

Features

Interprets FHIR StructureMaps and applies their transformations to the input parameter(s), performing cardinality corrections against a supplied StructureDefinition. The output resource(s) are explicitly not validated against the supplied StructureDefinition(s), as per the FHIR specifications.

Example usage

import transform from '@synanetics/fhir-transform';

const structureMap = {
  // structureMap FHIR resource
};

const content = {
  // source resource
};

// your structureDefinitionResolver can be as elaborate as you like, perhaps returning from a URL or a cache
const structureDefinitionResolver = async (url: string): Promise<any> => {
  switch (url) {
    case 'http://example.com/StructureDefinition/CustomResource':
      return {
        // profile definition
      };
    // whatever else
  }
};

// Your conceptMapResolver can be elaborate too, but needs to return the URL as the key object key.
// This is done so that you can choose to "follow" links to other ConceptMaps that may exist inside the
// first ConceptMap returned by the resolver.
const conceptMapResolver = async (url: string): Promise<Record<string, any>> => {
  const record: Record<string, any> = {};
  
  const map = await fetch(url);
  record[url] = await map.json();
  if (map.group[0].unmapped?.url) {
    const otherMap = await fetch(map.group[0].unmapped.url);
    record[map.group[0].unmapped.url] = await otherMap.json();
  }
};

// the structureMapResolver works exactly the same as the conceptMapResolver, so is not shown here.

const result = await transform({
  content,
  structureMap,
  structureDefinitionResolver,
  conceptMapResolver,
});