TypeSpec Fastify Emitter

Generates Fastify server code from TypeSpec HTTP service definitions using the Alloy Framework.

> [!IMPORTANT]
> This project is in early development and not production-ready. Expect breaking changes and missing features.

Installation

``bash
npm install --save-dev typespec-fastify
`

Features

- Route handlers generated from TypeSpec operations
- TypeScript operation interfaces for business logic
- Automatic parameter extraction (path, query, headers, body)
- Type-safe code generation
- User-controlled server lifecycle

Usage

$3

Create tspconfig.yaml:

`yaml
emit:
- "typespec-fastify"
options:
"typespec-fastify":
"output-dir": "{project-root}/src/generated"
`

$3

Create main.tsp:

`typespec
import "@typespec/http";
using TypeSpec.Http;

@service
namespace PetStore;

model Pet {
id: int32;
name: string;
age: int32;
}

@route("/pets")
interface Pets {
@get list(@query limit?: int32): Pet[];
@get get(@path petId: int32): Pet;
@post create(@body pet: Pet): Pet;
}
`

$3

`bash
npx tsp compile .
`

$3

`typescript
import fastify from "fastify";
import { registerRoutes } from "./generated/router.js";
import type { Pets } from "./generated/operations/pets.js";

const petsOperations: Pets = {
async list(options) {
return [{ id: 1, name: "Fluffy", age: 3 }];
},
async get(petId) {
return { id: petId, name: "Fluffy", age: 3 };
},
async create(body) {
return { ...body, id: 123 };
},
};

const server = fastify({ logger: true });
await registerRoutes(server, { pets: petsOperations });
await server.listen({ port: 3000 });
``

Architecture

Built with:

- Alloy Framework (JSX-based code generation)
- TypeSpec HTTP (service definitions)
- TypeSpec Emitter Framework (compiler integration)

Contributing

Contributions welcome.

License

MIT