discontinuedPackage fhir_db has been discontinued and replaced by fhir_r4_db.

parseReference function

ReferenceComponents parseReference(String? referenceString)

Parses a literal reference into base URL, type, id and version.

R4B references.html "Literal References" (read 2026-09-07) gives the shape as a regex: an optional (http|https):// base of one or more path segments, then [type]/[id], then optionally (\/_history\/[A-Za-z0-9\-\.]{1,64})?. So the version suffix comes off first, whatever the rest is, and the base is everything before the LAST /[type]/[id]. An absolute versioned reference used to be split on its last two segments and indexed as type _history, id [vid], and a base path that happened to contain the type name was cut at the first occurrence (fhirant REVIEW-2026-09-06 finding 18).

Implementation

ReferenceComponents parseReference(String? referenceString) {
  if (referenceString == null || referenceString.isEmpty) {
    return const ReferenceComponents();
  }

  String? version;
  var rest = referenceString;
  const historyMarker = '/_history/';
  final h = rest.indexOf(historyMarker);
  if (h >= 0) {
    final v = rest.substring(h + historyMarker.length);
    version = v.isEmpty ? null : v;
    rest = rest.substring(0, h);
  }

  // Absolute URLs: "http://example.org/fhir/Patient/123"
  if (rest.startsWith('http://') || rest.startsWith('https://')) {
    final uri = Uri.tryParse(rest);
    if (uri == null) return const ReferenceComponents();
    final pathSegments = uri.pathSegments.where((s) => s.isNotEmpty).toList();
    if (pathSegments.length >= 2) {
      final type = pathSegments[pathSegments.length - 2];
      final id = pathSegments[pathSegments.length - 1];
      final cut = uri.path.lastIndexOf('/$type/$id');
      return ReferenceComponents(
        baseUrl: '${uri.scheme}://${uri.authority}'
            '${uri.path.substring(0, cut + 1)}',
        resourceType: type,
        id: id,
        version: version,
      );
    }
    return const ReferenceComponents();
  }

  // Relative references: "Patient/123"
  final parts = rest.split('/');
  if (parts.length == 2) {
    return ReferenceComponents(
      resourceType: parts[0],
      id: parts[1],
      version: version,
    );
  }

  // ID-only references
  if (!rest.contains('/')) {
    return ReferenceComponents(id: rest, version: version);
  }

  return const ReferenceComponents();
}