Feature request: allow parser set event type of handler with middy

[yamatatsu]

Use case

middy can pass event type like as this. So we can pass inferred event type from zod schema to handler.

Solution/User Experience

const detailSchema = z.object({
	date: z.string().regex(/^\d{4}-\d{2}-\d{2}$/),
	message: z.string(),
});

export const handler = middy()
	// when using parser
	.use(parser({ schema: detailSchema, envelope: EventBridgeEnvelope }))
	// handler will get event type already inferred without type annotation.
	.handler(async (event) => {
		logger.inf(event.detail.message)
	});

Alternative solutions

No response

Acknowledgment

• This feature request meets Powertools for AWS Lambda (TypeScript) Tenets
• Should this be considered in other Powertools for AWS Lambda languages? i.e. Python, Java, and .NET

Future readers

Please react with 👍 and your use case to help us understand customer demand.

[am29d]

Hey @yamatatsu, thanks for raising the issue.

In your example, I think you missed the types in the middy() call. Can you modify the solution code block to reflect that? In the meantime, I will investigate how we could add event types to middy call.

Edit: now that Andrea pointed out to me, I got your point more clearly. You want to infer the type in the handler if it comes after the parser. I'd need to investigate a bit more what it will take to implement it.

[github-actions]

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[github-actions]

This is now released under v2.6.0 version!