DataMapper

DataMapper turns Handlebars .hbs DSL files into REST endpoints. Place DSLs under DSL/<project>/<view>.hbs and call them with POST /<project>/<view>.

Intent. DataMapper shapes and normalizes payloads, so consumers (e.g., UIs) receive ready‑to‑use data without extra client‑side processing. It also acts as a contract layer between back‑end services, harmonizing formats and protocols from different providers. It’s an architecturally important, generic component rather than custom application logic.

Origin

Originally developed and maintained at the Information System Authority of Estonia (Riigi Infosüsteemi Amet, RIA) since June 2018. Design and development led by Rainer Türner until April 2025.

Original repository: https://github.com/buerokratt/DataMapper

Ownership

This cleaned repository is maintained by Rainer Türner starting from September 24, 2025, with an intention to have a clean version of DataMapper to work on, without affecting its owner RIA.

---

Quick start (Docker Compose v2)

git clone https://github.com/Buerostack/DataMapper.git
cd DataMapper
docker compose up -d --build datamapper

Health check:

curl -sS http://localhost:3000/healthz

---

Live development (mount DSLs)

docker-compose.yml mounts ./DSL into the container, so template edits apply immediately.

docker compose restart datamapper

---

Call a DSL

File: DSL/samples/ping.hbs
URL: POST /samples/ping

curl -sS -X POST http://localhost:3000/samples/ping   -H 'Content-Type: application/json'   -H 'type: json'   -d '{}'

Tip: If you prefer not to send type: json, set Accept: application/json or make your template output valid JSON—DataMapper returns JSON automatically when possible.

---

Project layout

DSL/
  └─ <project>/
       ├─ <view>.hbs           # POST /<project>/<view>
       └─ hbs/<view>.hbs       # optional fallback path
lib/
  └─ helpers.js                # Handlebars helpers (e.g., {{now}}, {{{json obj}}})
server.js                      # Express + Handlebars glue
Dockerfile
docker-compose.yml

---

Useful commands

Rebuild the image (refresh base image too):

docker compose build --pull datamapper

Start / Stop:

docker compose up -d datamapper
docker compose down

Logs:

docker compose logs -f datamapper

Shell inside the container:

docker exec -it datamapper sh

---

Troubleshooting

• “Cannot POST /…​” → The route didn’t match or the template path is wrong. Ensure the file exists at DSL/<project>/<view>.hbs.
• TemplateNotFound → Filename/paths don’t match the URL (no extension in the URL).
• TemplateOutputNotJson → You requested JSON but the template doesn’t render valid JSON. Fix the template or omit the JSON preference header.