Prerequisites

• I have written a descriptive issue title

Mongoose version

8.15.1

Node.js version

22.13.1

MongoDB version

8.0.4

Operating system

Linux

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

No response

Issue

The toJSON method returns any for the output type. I've attempted to specify the output type of the transform function, but due to the function signatures defined in document.d.ts, it gets widened to any making it pointless. Is there some method I'm missing on how to do this? Everything I've been able to find online about this (and what I've seen after poking around mongoose internals) seems to indicate there's no way to do this currently.

If it isn't possible, would it make sense to update the toJSON return type to be dynamic? It might work if the transform function required a typing to be supplied (using any as a fallback to avoid breaking backwards compat) with generics and then toJSON would just use whatever the return type of the transform function is.