Wrong types for FastifyRegister with custom logger

[marcoreni]

Prerequisites

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

Fastify version

4.10.0

Plugin version

No response

Node.js version

18.12.0

Operating system

macOS

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

12.6.1

Description

We're using a custom logger (based on Pino) in our implementation. When using withTypeProvider, we're having some issues with Typescript and the registration of plugins / routes.

If I understand correctly, FastifyRegister does not use the generic for the logger, hence we're not able to pass the custom instance inside the register function.

Steps to Reproduce

import { TypeBoxTypeProvider } from "@fastify/type-provider-typebox";
import { fastify } from "fastify";
import { pino } from "pino";

const server = fastify({
	logger: pino(),
}).withTypeProvider<TypeBoxTypeProvider>();

type AppFastifyInstance = typeof server;

const routes = async (instance: AppFastifyInstance): Promise<void> => {
	instance.get("/bar", {}, async (res, reply) => {
		return reply.send("ok");
	});
};

/** "routes" goes in error */
await server.register(routes, {
	prefix: "/foo",
});

Expected Behavior

It should work :)

[RafaelGSS]

Good catch! Would you like to send a Pull Request to address this issue? Remember to add unit tests.

[jagu-sayan]

Same bug for me with almost all fastify plugins (sensible, formbody, compress, secure-session).
I don't have this bug with @fastify/static and @fastify/cors. See fastify/fastify-cors#223 (comment).

Workaround

import fastifySensible from "@fastify/sensible";
import type { SensibleOptions } from "@fastify/sensible";

app.register(
  fastifySensible as unknown as FastifyPluginCallback<SensibleOptions>,
  {},
);

[sinclairzx81]

@marcoreni Hi.

The issue may be related to server.register() as it's possible to replicate the issue without configuring a TypeProvider.

TypeScript Link Here

import { fastify } from "fastify";
import { pino } from "pino";

const server = fastify({ logger: pino() }) // <-- no configuration

const routes = async (instance: typeof server): Promise<void> => {
  instance.get("/bar", {}, async (res, reply) => {
    return reply.send("ok");
  });
}

await server.register(routes, { // <- error on routes
  prefix: "/foo",
});

However, it's possible to write your example code this way which mitigates type errors on .register().

TypeScript Link Here

import { TypeBoxTypeProvider } from "@fastify/type-provider-typebox";
import { fastify, FastifyInstance } from "fastify";
import { pino } from "pino";

// Configure the server to use the type provider.
const server = fastify({ logger: pino() }).withTypeProvider<TypeBoxTypeProvider>()

// Ensure instance is typed as FastifyInstance
const routes = async (instance: FastifyInstance) => {

  // Optional: Re-configure type provider within the plugin
  const configured = instance.withTypeProvider<TypeBoxTypeProvider>()

  // Define routes.
  configured.get("/bar", {}, (res, reply) => reply.send("ok"));
}

// Register plugin
await server.register(routes, { prefix: "/foo" }) // ok

Hope this helps!
S

[marcoreni]

@jagu-sayan , I think what you're encountering is a different bug. If I'm right, it's discussed here: #4241 .

@sinclairzx81 you're right, it's not related to TypeProvider per se. If I use your workaround I'll lose the TypeBox Provider type enhancements, since instance will be treated as the default FastifyInstance. Declaring the typeProvider on each plugin (I'm using plugins to declare routes in separate files) may not be the best solution. Anyway, I opened a PR to fix the problem.

[jagu-sayan]

Thanks @marcoreni
I do an import { fastify } from "fastify";, but I have "moduleResolution": "NodeNext" in my tsconfig.json, if I put "moduleResolution": "Node", my problem is reolved.

[Uzlopak]

We are currently fixing nodenext issues.