Support for discriminator objects inside schemas

[sm-Fifteen]

https://github.com/mrin9/RapiDoc/blob/9c5401f06f3f1fe162b1a80a540b45da26ae74db/docs/specs/petstore_extended.yaml#L781-L786

In the extended petstore OpenAPI example, the Pet schema has a petType tag that is used as a discriminator to determine which of the 3 variants of pet is actually used. Redoc supports it (see the POST /pet route) and adjusts the properties presented in the UI based on the value of the discriminator property. RapiDoc does not currently appear to support this, at least not in the way the above example does it. For the record, Swagger UI doesn't support it either, despite this being a standard OpenAPI property).

There was recently a discussion from the OpenAPI team to deprecate discriminator (see OAI/OpenAPI-Specification#2143), but the consensus now seems to be that it does have a clear purpose (namely: identify tagged unions) and should be kept.

[mrin9]

Well, at RapiDoc, we wont be supporting discriminator at least for the foreseeable future.
It is an extremely complex feature to implement in the context of RapiDoc with a very little return.

We did try to implement it in the past, but were not able to cleanly address certain complex cases involving other schema composition rules such as all-off, any-of, one-of

Redoc do supports discriminator but their implementation is buggy too.

[sm-Fifteen]

Do you happen to have any examples regarding those complex composition use cases, or in what ways Redoc's implementation turns out to be buggy? I understand your point on how this is a somewhat niche feature (as far as OpenAPI goes, anyway) and that the returns on user experience wouldn't be all that significant, but I'm curious to know about the implementation issues and pitfalls.

[mrin9]

a quick search of discriminatior issues in redoc's source has given me some

Redocly/redoc#1088
Redocly/redoc#1076
Redocly/redoc#1031
Redocly/redoc#862

there are more, I am just listed few of them

[pschichtel]

Would a pull request be welcome for this?