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AstrolaDB

Generating Code

This continues from Adding Relationships. We have four tables in a database. Now we’ll generate typed outputs and a working API from the same schema.

Export types

Section titled “Export types”
Terminal window
alab export -f typescript

This produces TypeScript interfaces for every table. The password column on auth_user is omitted because col.password_hash() is hidden from exports.

You can export in other formats too:

Terminal window
alab export -f python
alab export -f go
alab export -f rust

Every export reads from the same schema. Change a column once, re-export, and every language stays in sync.

Export the OpenAPI schema

Section titled “Export the OpenAPI schema”
Terminal window
alab export -f openapi

This produces an openapi.json file with:

  • Standard OpenAPI 3.0 type definitions for every table
  • x-db extensions carrying database-specific metadata (constraints, relationships, indexes, semantic type info)

This file is the portable, machine-readable description of your entire data model. Generators, custom tooling, and third-party tools like QuickType or openapi-generator can all consume it.

Run a generator

Section titled “Run a generator”

Generators transform the schema into arbitrary output files. Let’s use the built-in FastAPI example to produce a working Python API.

Download the generator:

Terminal window
alab gen add https://raw.githubusercontent.com/hlop3z/astroladb/main/examples/generators/generators/fastapi.js

This saves generators/fastapi.js. Now run it:

Terminal window
alab gen run generators/fastapi -o ./generated

The output:

generated/
├── auth/
│   ├── __init__.py
│   ├── models.py      # Pydantic models with enums and defaults
│   └── router.py      # CRUD endpoints
├── blog/
│   ├── __init__.py
│   ├── models.py
│   └── router.py
└── main.py            # FastAPI app wiring all routers

To run it:

Terminal window
cd generated
uv add fastapi[standard]
uv run fastapi dev main.py

Open http://localhost:8000/docs to see the interactive API documentation.

Two paths, same source

Section titled “Two paths, same source”

The exported types and the generated API both came from the same schema files. Neither required you to describe your data model a second time.

This is the core idea:

  • alab export gives you typed structures in any supported language.
  • alab gen gives you arbitrary file output — APIs, configs, documentation, anything a generator template can produce.
  • openapi.json is the portable artifact that any external tool can consume directly.

All three read from the same source of truth. Use whichever combination fits your project.

Where to go from here

Section titled “Where to go from here”