fastapi_sqlalchemy

Flagship example — FastAPI + SQLAlchemy

A tiny shop (customers and orders) operated by a Reins agent, showing the whole story end to end:

• auto-expose — build_orm turns the SQLAlchemy models into intent-level capabilities (find_orders, get_order_by_ref, update_order, …) with zero hand-written CRUD;
• compose — one hand-written, identity-scoped capability (find_my_orders) lives right alongside the generated ones;
• ask() answers read questions; run() performs writes that are gated for approval before they touch the database;
• row-level security scopes data to whoever is logged in;
• audit records every write attempt, PII-redacted;
• a <reins-chat> widget on the home page, and a JSON API, both scoped by the request's identity.

The deterministic walkthrough (no API key)

make demo          # from the repo root
# or:  python -m examples.fastapi_sqlalchemy.demo

It uses a scripted FakeModel, so it needs no network and no API key — you see the harness itself: the generated capabilities, a read answer, identity-scoped reads, a write pausing at a real approval prompt, and the audit trail.

The real server

pip install "reins[sqlalchemy]" fastapi uvicorn
export ANTHROPIC_API_KEY=sk-...          # or OPENAI_API_KEY / GEMINI_API_KEY / …
uvicorn examples.fastapi_sqlalchemy.app:app --reload

Then open http://localhost:8000/ for the chat widget, or call the API:

curl -s localhost:8000/ask -H 'Content-Type: application/json' \
     -H 'X-User: ada@shop.test' -d '{"goal": "what are my orders?"}'

The X-User header stands in for your real session cookie / JWT — swap _identity in app.py for however your app already authenticates. Writes (POST /run) are gated: on a server there is no terminal to approve at, so the default handler fails closed — wire your own approve= (a review queue, a Slack confirm, an allow-list) for real write access.

Files

• models.py — plain SQLAlchemy models + a seeded in-memory database.
• shop.py — build_orm auto-expose + the scoped find_my_orders capability.
• demo.py — the deterministic walkthrough (what make demo runs).
• app.py — the FastAPI server with the JSON API and the chat widget.