Request Handlers.md

Fastify decorators

Request handlers

Here the list of available HTTP methods decorators:

@GET, @HEAD, @PATCH, @POST, @PUT, @OPTIONS, @DELETE

There's also one special decorator for all methods: @ALL

Limitations:

• Decorators can't be mixed, and you can use only one decorator per class/method.

Signatures:

Decorators have same signature, which consist of two overloads:

First overload:

name	type	required	default	description
url	string	no	/	Route url which will be passed to Fastify
options	RouteShorthandOptions	no	{}	Config for route which will be passed to Fastify

Second overload:

name	type	required	default	description
url	RouteOptions	no	{}	Route url and config to be passed to Fastify

Request handler per class

Every handler should extend base RequestHandler class:

import { GET, RequestHandler } from 'fastify-decorators';

@GET('/')
class MyRequestHandler extends RequestHandler {
  async handler() {} // concrete implementation of abstract method in RequestHandler
}

Request handler per method

In controllers you can decorate every method with one of the request decorators:

import { FastifyReply, FastifyRequest } from 'fastify';
import { Controller, GET } from 'fastify-decorators';

@Controller()
class MyController {
  @GET()
  async handler(request: FastifyRequest, reply: FastifyReply) {}
}

Creating hooks

There are also decorator which allows using Fastify Hooks:

import { GET, Hook } from 'fastify-decorators';

@GET('/')
export default class Handler extends RequestHandler {
  public handle(): Promise<never> {
    return Promise.reject({ code: 'NOT_IMPLEMENTED' });
  }

  @Hook('onSend')
  async onSend(request, reply) {
    reply.removeHeader('X-Powered-By');
  }
}

Error handling

fastify-decorators provides abilities to handle error with @ErrorHandler decorator.

Decorator may accept error code or type to handle or be empty which means will handle all errors. Let's take a look on example:

import { FastifyReply, FastifyRequest } from 'fastify';
import { ErrorHandler, GET, RequestHandler } from 'fastify-decorators';

@GET('/handler-with-error')
export default class HandlerWithErrorHandler extends RequestHandler {
  public handle(): Promise<never> {
    return Promise.reject({ code: 'NOT_IMPLEMENTED' });
  }

  @ErrorHandler('NOT_IMPLEMENTED')
  handleNotImplemented(error: Error, request: FastifyRequest, reply: FastifyReply): void {
    reply.status(422).send({ message: 'Not implemented' });
  }
}