Support intersecting union types (concat an object with alternatives)

[mnahkies]

Runtime

node.js

Runtime version

22

Module version

17.13.3

Used with

@nahkies/openapi-code-generator

Any other relevant information

No response

What problem are you trying to solve?

Related: mnahkies/openapi-code-generator#282

In openapi 3 definitions you can intersect schemas with unioned schemas, essentially forming something like this in typescript terms:

(A | B) & C

At the moment the generator attempts to define this as something like:

const x = joi
  .alternatives()
  .try(
    joi
      .object()
      .keys({foo: joi.string().required()})
      .options({stripUnknown: true})
      .required(),
    joi
      .object()
      .keys({bar: joi.string().required()})
      .options({stripUnknown: true})
      .required(),
  )
  .required()
  .concat(
    joi
      .object()
      .keys({id: joi.string().required()})
      .options({stripUnknown: true})
      .required(),
  )
  .required()

However this results in a runtime error like:

[Error: Cannot merge type alternatives with another type: object]

(unit test here)

Do you have a new or modified API suggestion to solve the problem?

I'll skip that test for now, and leave it as a known issue, but it would be great if it would be possible to concat into alternatives.

Alternatives
I suspect I could probably come up with a way to detect definitions of this nature, and basically re-write / invert them such that it was a union of intersections, instead of an intersected union. Eg:

(A & C) | (A & C)

But I think this would probably be quite complicated to do correctly supporting arbitrary input.