Typescript error in handler parameters

[Kirby Simmons]

Describe the bug
The main Typescript compile error occurs when trying to accept { signal } parameter (https://middy.js.org/docs/writing-middlewares/timeouts) in the handler. The error is Types of parameters  abortControllerConfig  and  callback  are incompatible.

To Reproduce
How to reproduce the behavior:

1. Try to add the { signal } 3rd parameter to the handler in a typescript repo
2. Typescript compiler error should occur

Expected behavior
No typescript compile errors when trying to accept the signal parameter

Environment (please complete the following information):

• Node.js: 18
• Middy: 4.6.4
• AWS SDK 3

Additional context

[will Farrell]

Thanks for reporting. Apologies on the delay. Can you put a full example in the issue?

It might be as simple as a one line fix here https://github.com/middyjs/middy/blob/main/packages/core/index.d.ts#L71, if I'm understanding correctly. A PR is also welcome.

[Stephen Young]

@willfarrell I stumbled on this issue as well.

Property 'signal' does not exist on type 'Callback<...>'.

The line of code you highlighted is exactly where the issue exists. Middy is passing { signal } to the handler but the typescript MiddyInputHandler type expects a callback function.

It's perhaps as simple as changing the MiddyInputHandler type to:

type MiddyInputHandler<
  TEvent,
  TResult,
  TContext extends LambdaContext = LambdaContext
> = (
  event: TEvent,
  context: TContext,
  params: { signal: AbortSignal } // <--- an object instead of a callback

But I'm not familiar enough with Middy to know if this will break something else.

[will Farrell]

not familiar enough with Middy to know if this will break something else.

It shouldn't break anything else. Did you want to make the PR?

[will Farrell]

Closed with PR #1165