Extending Request object on exported preHandlerAsyncHookHandler

[niels-van-den-broeck]

💬 Question here

Hi there!
I wrote a preHandlerAsyncHookHandler to validate a request using a code which can be given through either the Body or QueryString of my requests.

When registering a route this function is given to the preHandler property.
Below code sample did the trick when I was on "v4.13.0", but after updating to "v4.23.2" I seem to be getting an error in my types.

What I'm trying to achieve is extending the Request object with following properties:

type Request = {
    Body: { validationCode?: string };
    Querystring: { validationCode?: string };
}

I am not sure on how to achieve this. I have looked into the docs but didn't really find a way there either.
Is there anyone who could give me a hand with this? Thanks in advance! 🙏

Code sample

  type AsyncPreHookHandler<Request extends RequestGenericInterface = RouteGenericInterface> =
    preHandlerAsyncHookHandler<
      RawServerDefault,
      RawRequestDefaultExpression<RawServerDefault>,
      RawReplyDefaultExpression<RawServerDefault>,
      Request
    >;

  const validateCode: AsyncPreHookHandler<{
    Body: { validationCode?: string };
    Querystring: { validationCode?: string };
  }> = async request => {
    let validationCode = request.body?.validationCode;

    if (!validationCode && request.query?.validationCode) {
      validationCode = request.query.validationCode;
    }

    if (!validationCode) throw unauthorized('INVALID_CODE');

    const codeItem = await server.ValidationCodeReadService.getCode(validationCode);

    if (!codeItem) throw unauthorized('INVALID_CODE');

    if (codeItem.userId !== request.session.user) throw unauthorized('INVALID_CODE');
    if (server.ValidationCodeReadService.isExpired(codeItem)) throw unauthorized('CODE_EXPIRED');
  };

Error message for reference:

Your Environment

• node version: 18.18.0
• fastify version: 4.23.2
• os: Mac