Typescript error - "type is declared but never used" in .ts. When it was used in interface

Question

Why typescript give me error "'HttpRequest' is declared but never used." when HttpRequest was used in interface? How to fix this?

import fp from 'fastify-plugin'
import fastify from 'fastify'
import { IncomingMessage } from 'http'
import { Http2ServerRequest } from 'http2'

//'HttpRequest' is declared but never used.
type HttpRequest = IncomingMessage | Http2ServerRequest

declare module 'fastify' {
  interface FastifyRequest<
    HttpRequest,
    Query = fastify.DefaultQuery,
    Params = fastify.DefaultParams,
    Headers = fastify.DefaultHeaders,
    Body = any
  > {
    user: string
  }
}

function plugin(fastify, options, next) {
  fastify.decorateRequest('user', 'userData')
  next()
}

export const reqDecorator = fp(plugin)

Here is the FastifyRequest interface:

interface FastifyRequest<HttpRequest = IncomingMessage, Query = fastify.DefaultQuery, Params = fastify.DefaultParams, Headers = fastify.DefaultHeaders, Body = any>

is this .ts file or .d.ts file?

Plochie
– Plochie

2019-11-22 12:34:42 +00:00
Commented Nov 22, 2019 at 12:34 — Plochie
– Plochie, Commented Nov 22, 2019 at 12:34
it's .ts file.......

ZiiMakc
– ZiiMakc

2019-11-22 12:46:20 +00:00
Commented Nov 22, 2019 at 12:46 — ZiiMakc
– ZiiMakc, Commented Nov 22, 2019 at 12:46

Plochie · Accepted Answer · 2019-11-22 12:13:25Z

1

You have not defined name for the type,

declare module 'fastify' {
  interface FastifyRequest<
    httpRequest = HttpRequest,

As IncomingMessage is used as type, again you need to give name for the type for FastifyRequest interface,

export interface FastifyRequest<httprequest = IncomingMessage, // added this
Query = fastify.DefaultQuery,
Params = fastify.DefaultParams,
Headers = fastify.DefaultHeaders,
Body = any> {
  // interface fields and methods
}

edited Nov 22, 2019 at 12:13

answered Nov 22, 2019 at 11:56

Plochie

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3 Comments

ZiiMakc Over a year ago

Added FastifyRequest interface. If i do like HttpRequest = HttpRequest i've get "All declarations of 'FastifyRequest' must have identical type parameters"

ZiiMakc Over a year ago

but FastifyRequest is part of fastify framework, i can't modify it and export ;/ Or i just don't understand something

ZiiMakc Over a year ago

httprequest = IncomingMessage gives the same error: "All declarations of 'FastifyRequest' must have identical type parameters"

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