Is it possible to customise type resolution?

[paulst-cais]

We want to be able to treat Date types differently in our app, and keep [de]serialisation in the API layer.

So where the the spec for a schema property might look like:

  dueDate:
    type: string
    format: date

This currently gets translated to a string primitive.

In our custom fetcher we can add deserialisation which actually turns this into a simple struct for holding the Date, giving us better type safety. However, this will then not match the typed response for a specific endpoint, which would be expecting a string.

It's not clear to me if there is a way to achieve this custom resolver at the moment?

I would expect to be able to pass some configuration key to register a new resolver, ideally it would only have to handle the overridden scenario, and be able to fallback to default resolution, so a custom resolver might do something like:

function resolveDate(property: OpenAPIProperty): string | undefined {
    if (property.type === 'string' && property?.format === 'date') {
       return 'LocalDate'
    }
}

Is this something that would be useful? I'm a little unsure about resolving to a non-primitive type here, as that would need to be imported / defined in the file; not sure the cleanest way to configure that?

If this isn't currently possible I'd possibly be able to work on a solution if that is something you'd want to add? I'd need some pointers on where best to hook into the code to do this though :)

[paulst-cais]

Just looking into this a little further, it does seem that this is partly implemented here:

https://github.com/anymaniax/orval/blob/97ced54e2a39f93d2e16e32255ca28b80ad9582b/packages/core/src/getters/scalar.ts#L106-L110

Ideally though I want to treat a Date and a DateTime differently, and type them differently to help distinguish between them. I think most of this could be done in this file though:

if (context.output.override.customStringFormatResolver && item?.format) {
    const type = context.output.override.customStringFormatResolver(item.format);
    if (type) {
       value = type;
    }
}

Then a example resolver can just do something like:

customStringFormatResolver = (format: string) => {
   switch (format) {
      case 'date-time':
        return 'CustomDateTime'
      case 'date':
        return 'CustomDate'
      default:
        return false
   }
}