@typespec-tools/emitter-express

TypeSpec library for emitting a helper function to build type-safe Express routes a TypeSpec DSL using the @typespec/http library.

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[!WARNING] This library uses the current emitter-framework that is set to be updated, which could cause breaking changes.

Disclaimer: Please note that this library is not officially affiliated with TypeSpec or Azure. It is an independent project started by @codingmatty.

Features / Roadmap

• [x] Emit a function that can build type-safe Express routes
• [ ] Add support for typed responses based on status codes
• [ ] Add support for authorization
• [ ] Add support for header types
• [ ] Add support for Zod schema validation of inputs: Path, Query, Body.
• [ ] Add support for Zod schema validation of output body

Install

npm install @typespec-tools/emitter-express

Emitter

Usage

1. Via the command line

tsp compile . --emit=@typespec-tools/emitter-express

2. Via the config

emit:
  - "@typespec-tools/emitter-express"

The config can be extended with options as follows:

emit:
  - "@typespec-tools/emitter-express"
options:
  "@typespec-tools/emitter-express":
    option: value

Examples

Given the following Typespec:

import "@typespec/http";

enum petType {...}
model Pet {...}

@route("/pets")
namespace Pets {
  @get
  op listPets(@query type?: petType): {
    @body pets: Pet[];
  };
}

This emitter will allow you to implement the following:

import { createTypedRouter } from 'tsp-output/@typespec-tools/emitter-express/output";

const app = express();
const router = express.Router();

typedRouter = createTypedRouter(router);

typedRouter.Pets.listPets((req, res) => {
  // req.query.type is typed as petType enum
  // the response has type: { pets: Pet[] }
  res.json({ pets: [...] });
});

app.use(typedRouter.router);

Alternatively, you can implement a single namespace:

import { createPetsRouter } from 'tsp-output/@typespec-tools/emitter-express/output";

export const router = express.Router();

typedPetsRouter = createPetsRouter(router);

typedPetsRouter.listPets((req, res) => {
  // req.query.type is typed as petType enum
  // the response has type: { pets: Pet[] }
  res.json({ pets: [...] });
});

Emitter options

Option	Type	Default	Description
output-file	string	"output.ts"	Name of the output file