Using separate NewError function for multiple API instances

[kralewitz]

Hello, I have a single go program which provides two separate huma.APIs. For one API, I'd like to keep the RFC9457 error responses which are used by default, but for the other API I need to use a custom error response due to legacy reasons. I'd also like to use the default validators for both APIs.

Now since the NewError function is defined as a package-level var, it looks like there's no easy way to use a different default error response for each API instance and I basically have two options:

1. Use a shared error model for both APIs (not ideal, as it will pollute the legacy error response with the RFC9457 fields and vice-versa)
2. Use a Transformer on the legacy API instance to convert the RFC9457 error model to the legacy model

Is there another way that I missed?

If not, might I suggest embedding the NewError function directly in the huma.API instance, maybe during initialization via the Config struct? Looking at the source code, it seems to be used in the Register and WriteErr functions, which both have access to the API instance. This would however leave the package-level Error* utility functions tied only to the global NewError func.

Anyway, thanks for the work you've put into the framework, I like the features very much and this is the only minor hiccup I have run into so far :)

[danielgtaylor]

@kralewitz sorry for the delay. You are correct that this isn't currently easy to do in one service. Both your options would work in my opinion.

I almost made the NewError function a property of the API when designing it, but since handler functions don't have access to the API directly and the huma.Error*(...) functions are used to return errors it didn't make sense. I haven't been able to figure out a way around that. Open to ideas, but also don't want to break existing users!

[danielgtaylor]

Moving this to a discussion as this needs a design and I'm not sure how to approach it, feel free to discuss and provide a design that handles the utility error functions.