Migration to v4.md

Migration from v3.x to v4.x

This guide describes how to migrate from fastify-decorators v3 to v4.

Note: migration guide from v2.x to v3.x is here.

Moving to ESM

What's changed

v3	v4
CJS + ESM	only ESM

How to reflect

In general there are only few steps to be done:

1. In package.json: set "type" field value to "module"
2. In tsconfig.json: set "module" to ESNext or ES2020
3. In tsconfig.json: set "target" to ES2015 or newer

Q&A section

Q: How can I adjust tests to work properly with newer version? A: See Testing documentation

Q: I'm using __dirname or __filename in my project A: There's "polyfill" for them, just add this lines to file which uses these variables:

import { fileURLToPath } from 'node:url';
import { dirname } from 'node:path';

const __filename = fileURLToPath(import.meta.url);
const __dirname = dirname(__filename);

Built-in DI was moved to plugin

What's changed

v3	v4
Built-in DI	DI moved to @fastify-decorators/simple-di

How to reflect

In order to keep previous behavior there are 3 steps:

1. Add @fastify-decorators/simple-di to your application with your favorite package manager

2. Remove reflect-metadata and explicit import of this library, simple-di package will import it itself

3. Update imports in your application, for example:

   Before:

   import { Controller, GET, Initializer, Inject, Service } from 'fastify-decorators';
   
   @Service()
   class SampleService {
     @Initializer()
     async initializeService() {
       // some async stuff here
     }
   }
   
   @Controller('/')
   export class SampleController {
     @Inject(SampleService)
     private service!: SampleService;
   
     @GET()
     async handleRequest() {
       // some stuff with service
     }
   }

   After:

   import { Controller, GET } from 'fastify-decorators';
   import { Initializer, Inject, Service } from '@fastify-decorators/simple-di';
   
   @Service()
   class SampleService {
     @Initializer()
     async initializeService() {
       // some async stuff here
     }
   }
   
   @Controller('/')
   export class SampleController {
     @Inject(SampleService)
     private service!: SampleService;
   
     @GET()
     async handleRequest() {
       // some stuff with service
     }
   }