Template-Driven HL7 → FHIR Conversion

The fastest way to produce a FHIR resource from an HL7 v2 message is to store a JSON template of the resource as a System Variable with embedded node tags, then call qie.evaluateTemplate() from a mapping node to substitute the source values. The template is written once and re-used across every channel that produces that resource type.

A minimal Patient template stored as a System Variable named PatientTemplate looks like this:

{
  "resourceType": "Patient",
  "id": "/*{s:PID-3.1}*/",
  "identifier": [
    { "system": "urn:oid:1.2.3.4.5", "value": "/*{s:PID-3.1}*/" }
  ],
  "active": true,
  "name": [
    {
      "use": "official",
      "family": "/*{s:PID-5.1}*/",
      "given": [ "/*{s:PID-5.2}*/", "/*{s:PID-5.3}*/" ]
    }
  ],
  "gender": "/*{s:PID-8}*/",
  "birthDate": "/*{s:PID-7}*/",
  "address": [
    {
      "line": [ "/*{s:PID-11.1}*/" ],
      "city": "/*{s:PID-11.3}*/",
      "state": "/*{s:PID-11.4}*/",
      "postalCode": "/*{s:PID-11.5}*/",
      "country": "/*{s:PID-11.6}*/"
    }
  ]
}

The /*{ ... }*/ wrappers are JSON-safe node tags. The comment markers keep the template parseable as JSON in editors and validators, and QIE strips them at evaluation time. The s: prefix reads from the Source message; use m: for the working Message or mc: for the messageCache.

The mapping-node script that applies the template is short:

var patient = qie.evaluateTemplate(
   qie.getVariable('PatientTemplate'),  // template
   null,                                // parameters
   null,                                // escapeFor
   true                                 // isJSON
);

message = qie.createJSONMessage('{}');
message.setNode('/', patient);

The fourth argument (isJSON = true) tells QIE to escape substituted values for JSON. Special characters in PID-5.1 like quotes or backslashes are escaped so the produced JSON stays well-formed.

For a step-by-step build of an end-to-end channel that ingests an ADT message and POSTs a Patient resource to a public FHIR sandbox, see HL7 v2 to FHIR with a Template in the FHIR Quickstart.