Fastify Autoload ES Modules

NOTE The fastify-autoload plugin automatically works with ESM in Node as of Version 3. If you are using this module and upgrade to Fastify 3, replace this module with the official Fastify module.

I wrote this because I want to be able to use ES Modules (ESM) with Fastify and Node 12+. It has been tested to work in a Node 14.x environment as of 2020-05-01. Once Node 12.x is no longer in LTS, and if the default Fastify Autoload module has not yet added in this functionality, I shall remove any --experimental-modules flags from the project.

This is not meant to be an ESM Compatible fork of fastify-autoload, as I don't have a lot of free time to map all of the use cases out.

Things this Fastify plugin does:

1. Allows you to have an autoloader with ESM

Things this plugin does not do:

1. Work with TypeScript -- at least in my quick and dirty tests of it. Perhaps I'll add the ability in once I learn more about the interactions of TypeScript with ESM in a Node environment.

Installation

yarn add fastify-esm-autoload
# or npm install --save fastify-esm-autoload

Usage

You must use this from within a Node ESM module. This means either using the .mjs extension, or setting "type":"module" on the top level of your package.json file.

// server.js
import { resolve } from 'path';

import Fastify from 'fastify';
import Autoload from 'fastify-esm-autoload';

const fastify = Fastify();

fastify.register(Autload, {
  dir: resolve(process.cwd(), 'routes');
});

fastify.listen(3000, (err)=> {
  if(err) {
    console.error(err);
    process.exit();
  }
  console.log('Listening')
});

// routes/main.js
export default async (fastify) => {
  fastify.get('/', async () => {
    return 'working!';
  });
  return true;
}

Then, in your console run

node --experimental-modules server.js

NOTE

In Node's ESM there is not the __dirname constant, so if your code relies on that, a simple fix is to do the following:

import { resolve } from 'path';
const __dirname = resolve('.');
// or you could just use this code directly.

fastify.register(Autoload, {
  dir: resolve('.','routes')
})

Because you may want to pass options to a specific group of autoloaded plugins, you can do so like this:

// server.js
import {resolve} from 'path';

import Fastify from 'fastify';
import Autoload from 'fastify-esm-autoload';

const fastify = Fastify();

fastify.register(Autoload, {
  dir: resolve(process.cwd(), 'grouped'),
  options: {
    something: 'some value '
  }
});

Auto Prefix

If you would like to apply a prefix to all routes in a file, you can do this by exporting a constant called autoPrefix.

//server.js
import {resolve} from 'path';
import Fastify from 'fastify';
import Autoload from 'fastify-esm-autoload';
const fastify = Fastify();

fastify.register(Autoload, {
  dir: resolve(process.cwd(), 'routes')
});

//routes/posts.js
export default async (fastify) => {

  // will be registered under /posts
  fastify.get('/', async () => 'Post Index');
  // will be registered under /posts/:id
  fastify.get('/:id', async (req) => 'Post with ID of '+ req.params.id);
  // other routes...
  return true;
};
export const autoPrefix = '/posts';

NOTE My auto prefix is not the same as the official Fastify Autoload. My auto prefix implementation will override any prefix given in the options object when the plugin is loaded. For example:

// same imports as above example
fastify.register(Autoload, {
  dir: resolve(process.cwd(), 'routes'),
  prefix: '/defaultPrefix'
});

// routes/user.js
export default async (fastify) => {
  // Will NOT be registered at /defaultPrefix/user
  // WILL be registered at /user
  fastify.get('/', async () => 'Routes/User')
  return true;
}

export const autoPrefix = '/user';

Auto Prefixing

For the given file structure

If we do the following

fastify.register(Autoload, {
  dir: resolve(process.cwd(), 'routes');
});

The routes added in file1.js and file2.js will have path1/ prefixed automatically.

Similarly, the routes in file3.js and file4.js will have their routes prefixed with path2.

NOTE This only goes one level deep. It will not work with any folders inside of path1/ or path2/

CommonJS Interoperability

The plugin has been tested to work with .js files in a folder with {"type":"commonjs"} using module.exports = ... in place of export default ..., so if for some reason you want to use this plugin within a CJS environment, you shouldn't run into any errors.

Type Definitions

This package comes with it's own TypeScript definitions; no @types/ repo necessary!