Fastify Typescript request query

Question

I'm trying to put together a simple endpoint following the Fastify with Typescript docs here:

https://www.fastify.io/docs/v3.1.x/TypeScript/

export default async function foo(fastify: any) { const MyInstance = new Foo(fastify.db); app.get<{ Querystring: IQueryString, Headers: IHeaders }>( "/foo", async (request: FastifyRequest, reply: FastifyReply) => { console.log(request.query); // *prints query object* const { queryObj } = request.query; // *Gives error: Object is of type 'unknown'* const result = await MyInstance.getFoo(queryObj); reply.status(200).send(result); } ); }

Why do I get the error when I try to access the request.query object and how do I fix it?

Never annotate the types of inline callback parameters. Instead, use type inference. That is async (request, reply) => instead of async (request: FastifyRequest, reply: FastifyReply) =>. Note: the examples in the docs you linked do this properly — Aluan Haddad
– Aluan Haddad, Commented Apr 27, 2021 at 18:57
That fixes the error. However, type inference doesn't seem to work on async(request, reply) . I get no implicit any on request and reply. — Aakshaye
– Aakshaye, Commented Apr 27, 2021 at 19:53

Jérôme Beau · Accepted Answer · 2022-12-28 12:56:20Z

By default FastifyRequest.query's type RequestQuerystringDefault maps to unknown because one cannot guess which attributes/type you'll want to set for it.

Should you have a defined type for the query of some request, just define that request type and use it:

type MyRequest = FastifyRequest<{ Querystring: { queryObj: MyQueryObject } }>

then specify it as the expected request type:

 async (request: MyRequest, reply: FastifyReply) => { const { queryObj } = request.query // Ok }

Collectives™ on Stack Overflow

Fastify Typescript request query

1 Answer 1

1 Comment

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Linked

Related