Performance (Fastify)
By default, Nest makes use of the Express framework. As mentioned earlier, Nest also provides compatibility with other libraries, such as Fastify. Nest achieves this framework independence by implementing a framework adapter whose primary function is to proxy middleware and handlers to appropriate library-specific implementations.
Hint Note that for a framework adapter to be implemented, the target library must provide request/response pipeline processing similar to what's found in Express.
Fastify provides a good alternative framework for Nest because it solves design issues in a similar manner to Express. However, Fastify is much faster than Express, achieving nearly twice the benchmark results. A fair question, then, is why Nest uses Express as the default HTTP provider. The reason is that Express is widely used, well known, and has an enormous set of compatible middleware, which is available to Nest users out of the box.
But since Nest provides framework independence, you can easily migrate between the two. Fastify can be a better choice when raw speed is a priority. To utilize Fastify, simply choose the built-in FastifyAdapter as shown in this chapter.
Installation#
First, we need to install the required package:
$ npm i --save @nestjs/platform-fastify
Adapter#
Once the Fastify platform is installed, we can use the FastifyAdapter.
import { NestFactory } from '@nestjs/core';
import {
FastifyAdapter,
NestFastifyApplication,
} from '@nestjs/platform-fastify';
import { AppModule } from './app.module.js';
async function bootstrap() {
const app = await NestFactory.create<NestFastifyApplication>(
AppModule,
new FastifyAdapter()
);
await app.listen(process.env.PORT ?? 3000);
}
await bootstrap();
By default, Fastify listens only on the localhost 127.0.0.1 interface (read more). If you want to accept connections on other hosts, you should specify '0.0.0.0' in the listen() call:
async function bootstrap() {
const app = await NestFactory.create<NestFastifyApplication>(
AppModule,
new FastifyAdapter(),
);
await app.listen(3000, '0.0.0.0');
}
Platform specific packages#
Keep in mind that when you use the FastifyAdapter, Nest uses Fastify as the HTTP provider. This means that each recipe that relies on Express may no longer work. You should use Fastify-equivalent packages instead.
Redirect response#
Fastify handles redirect responses slightly differently than Express. To do a proper redirect with Fastify, return both the status code and the URL, as follows:
@Get()
index(@Res() res) {
res.status(302).redirect('/login');
}
Fastify options#
You can pass options into the Fastify constructor through the FastifyAdapter constructor. For example:
new FastifyAdapter({ logger: true });
Middleware#
Middleware functions retrieve the raw req and res objects instead of Fastify's wrappers. This is how the middie package, which Fastify uses under the hood, works - check out this page for more information.
import { Injectable, NestMiddleware } from '@nestjs/common';
import { FastifyRequest, FastifyReply } from 'fastify';
@Injectable()
export class LoggerMiddleware implements NestMiddleware {
use(req: FastifyRequest['raw'], res: FastifyReply['raw'], next: () => void) {
console.log('Request...');
next();
}
}
import { Injectable } from '@nestjs/common';
@Injectable()
export class LoggerMiddleware {
use(req, res, next) {
console.log('Request...');
next();
}
}
Route Config#
You can use the route config feature of Fastify with the @RouteConfig() decorator.
@RouteConfig({ output: 'hello world' })
@Get()
index(@Req() req) {
return req.routeConfig.output;
}
Route Constraints#
As of v10.3.0, @nestjs/platform-fastify supports the route constraints feature of Fastify with the @RouteConstraints decorator.
@RouteConstraints({ version: '1.2.x' })
newFeature() {
return 'This works only for version >= 1.2.x';
}
Hint@RouteConfig()and@RouteConstraintsare imported from@nestjs/platform-fastify.
Example#
A working example is available here.
