I new to and trying out Fastify with Typescript. I am unable to figure out why the name in the const {name} = req.query section is throwing a type error:

Property 'name' does not exist on type 'unknown'.ts(2339)

Shouldn’t the schema: already provide type inference on the name? Or do I need to further add types for the req variable?

Full code:

import { Type } from '@sinclair/typebox';
import { FastifyPluginAsyncTypebox } from '@fastify/type-provider-typebox'
import { FastifyInstance } from 'fastify';

const plugin: FastifyPluginAsyncTypebox = async function(fastify: FastifyInstance) {
  fastify.get('/', {
    schema: {
      querystring: Type.Object({
        name: Type.String({ default: 'world' })
      }),
      response: {
        200: Type.Object({
          hello: Type.String()
        })
      }
    }
  }, (req) => {
    const { name } = req.query;
    return { hello: name };
  });

  fastify.post('/', {
    schema: {
      body: Type.Object({
        name: Type.String()
      }),
      response: {
        200: Type.Object({
          hello: Type.String()
        })
      }
    }
  }, async (request) => {
    const { name } = request.body;
    return { hello: name || 'world' };
  });
}

export default plugin;

Other files:

tsconfig.json

{
  "extends": "fastify-tsconfig",
  "compilerOptions": {
    "outDir": "build",
    "target": "es2018",
    "lib": ["es2018"]
  }
}

package.json

{
  "name": "fastify",
  "version": "1.0.0",
  "main": "index.js",
  "scripts": {
    "build": "tsc -p tsconfig.json",
    "start": "node index.js"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "description": "",
  "dependencies": {
    "fastify": "^4.27.0"
  },
  "devDependencies": {
    "@fastify/autoload": "^5.8.2",
    "@fastify/swagger": "^8.14.0",
    "@fastify/swagger-ui": "^3.0.0",
    "@fastify/type-provider-typebox": "^4.0.0",
    "@sinclair/typebox": "^0.32.30",
    "@tsconfig/recommended": "^1.0.6",
    "@types/node": "^20.12.11",
    "fastify-tsconfig": "^1.0.0",
    "typescript": "^5.4.5"
  }
}

Original repo: https://github.com/mcollina/type-safe-fastify/blob/main/routes/root.ts
Original video: https://www.youtube.com/watch?v=hx6jy3MzQzw