Multi-Version FHIRPath Server

A high-performance FHIRPath evaluation server using Bun runtime, supporting multiple FHIR versions (R4, R5, R6-ballot3) with the @atomic-ehr/fhirpath library.

Features

• Multi-version FHIR Support: R4, R5, and R6-ballot3
• High Performance: Built with Bun runtime and native web server
• Zero External Dependencies: Only Bun + your FHIRPath library
• Auto-version Detection: Automatically detect FHIR version from resources
• Debug Support: AST parsing and trace information
• CORS Ready: Built-in CORS support for web applications

Quick Start

Prerequisites

• Bun runtime installed
• Local @atomic-ehr/fhirpath library (included via file reference)

Installation

# Install dependencies
bun install

# Start development server with hot reload
bun run dev

# Or start production server
bun run start

Usage

The server will start on http://localhost:3000 by default.

API Endpoints

Information

• GET / - API information and supported features
• GET /health - Health check endpoint

FHIRPath Evaluation

• POST /r4 - Evaluate expressions using FHIR R4
• POST /r5 - Evaluate expressions using FHIR R5
• POST /r6 - Evaluate expressions using FHIR R6-ballot3
• POST / - Auto-detect FHIR version and evaluate

Request Format

All FHIRPath evaluation endpoints expect a FHIR Parameters resource:

{
  "resourceType": "Parameters",
  "parameter": [
    {
      "name": "expression",
      "valueString": "Patient.name.given.join(' ')"
    },
    {
      "name": "resource",
      "resource": {
        "resourceType": "Patient",
        "name": [{"given": ["John"], "family": "Doe"}]
      }
    }
  ]
}

Examples

Basic Evaluation

curl -X POST http://localhost:3000/\$fhirpath-r4 \
  -H "Content-Type: application/fhir+json" \
  -d '{
    "resourceType": "Parameters",
    "parameter": [
      {
        "name": "expression",
        "valueString": "Patient.gender"
      },
      {
        "name": "resource",
        "resource": {
          "resourceType": "Patient",
          "gender": "female"
        }
      }
    ]
  }'

Development

# Development with hot reload
bun run dev

# Build for production
bun run build

# Run tests
bun test

This project was created using bun init and leverages Bun's native web server capabilities.