Hooks

Fastify allows you to listen to specific events in the application or request/response lifecycle.

By using hooks you can interact directly with the lifecycle of Fastify.

Available Hooks

Request/Reply

• onRequest
• preParsing
• preValidation
• preHandler
• preSerialization
• onError
• onSend
• onResponse
• onTimeout
• onRequestAbort

Application

• onReady
• onListen
• onClose
• preClose
• onRoute
• onRegister

Registering Hooks

Hooks can be registered at providers by simply exporting a function with their respective name.

src/providers/hooks.ts

import type { FastifyReply, FastifyRequest } from 'fastify';

export type MyProvider = true;

export default function (): MyProvider {
  return true;
}

// These functions must respect their parameter signature
// read more in the official Fastify documentation
// https://fastify.dev/docs/latest/Reference/Hooks
export async function onRequest(request: FastifyRequest, reply: FastifyReply) {
  // Your logic here
}

Example

A good example to demonstrate how hooks can be used is with Prisma or any other ORM that you are using.

View the example here