[FSTDEP004] FastifyDeprecation

[siemah]

Prerequisites

• I have written a descriptive issue title
• I have searched existing issues to ensure it has not already been reported

Fastify version

3.20.2

Plugin version

3.0.0

Node.js version

12.22.3

Operating system

macOS

Operating system version (i.e. 20.04, 11.3, 10)

10.15.7

Description

I tried to call preParsing hook using the async way as suggested in the documentation:

fastify.addHook('preParsing', async (request, reply, payload) => {
  // Some code
  return payload;
})

and when i take a look at my terminal i found this warning:

(node:37541) [FSTDEP004] FastifyDeprecation: You are using the legacy preParsing hook signature. Use the one suggested in the documentation instead.
server listening on http://[::1]:4321

then i tried the other way:

fastify.addHook('preParsing',  (request, reply, payload, done) => {
  // Some code
  return done(null, payload);
})

i didnt find any warning.

Steps to Reproduce

• Create a fastify server
• Add preParsing hook using the code above

Expected Behavior

No response

[climba03003]

I cannot reproduce your problem.
https://replit.com/@climba03003/fastify-issue-3284

[siemah]

Hey @climba03003 check this code for the server.ts:

import fastify from 'fastify';

const server = fastify();

server.register(async(app) => {
  app.addHook('preParsing', async(req, rep,pay) => {
    console.log('here from "preParsing" hook')
    return pay;
  })
  app.get('/warning', async(req, rep) => {
    return {
      hello: "hola"
    }
  })
})
server.listen(3000)

and this is package.json

{
  "dependencies": {
    "fastify": "^3.20.2",
    "fastify-plugin": "^3.0.0",
    "fastify-sequelize": "^1.0.4",
    "mysql2": "^2.3.0",
    "pino-pretty": "^6.0.0"
  },
  "devDependencies": {
    "@tsconfig/node12": "^1.0.9",
    "@types/node": "^16.7.1",
    "nodemon": "^2.0.12",
    "ts-node": "^10.2.1",
    "typescript": "^4.3.5"
  },
  "scripts": {
    "dev": "nodemon src/server.ts",
    "build": "tsc -p tsconfig.json"
  }
}

Note:

This warning printted when i use fastify with ts-node and typescript

[climba03003]

@siemah
I cannot reproduce it by using TypeScript.

[siemah]

@climba03003
I create this repos to produce the same warning i got

[climba03003]

It should be the TypeScript transpile problem.

We test the function against AsyncFunction constructor and your target is es5 which do not have AsyncFunction.
I will mark it as wontfix as we do not have any other good way to test it.

Change the target greater than es2017 will solve the issue

[siemah]

@climba03003
I think the documentation need to be updated to inform devs to update target to "es2017" after generating the tsconfig using npx tsc --init

[climba03003]

@climba03003
I think the documentation need to be updated to inform devs to update target to "es2017" after generating the tsconfig using npx tsc --init

@siemah Feel free to send a PR for the documentation improvement.