I’m trying to write a minimal, custom, JSON:API 1.1 implementation using Python.

For the top level, the RFC/doc says:

https://jsonapi.org/format/#document-top-level

A document MUST contain at least one of the following top-level members:

• data: the document’s “primary data”.
• errors: an array of error objects.
• meta: a meta object that contains non-standard meta-information.
• a member defined by an applied extension.

The members data and errors MUST NOT coexist in the same document.

The way I read that is:

• “data” is optional
• “errors” is optional
• “meta” is optional
• “member from an extension” is optional

However, at least 1 of them needs to be present in the document. Also “data” and “errors” must never be in the same document.

I’m having a hard time modeling this. Is there a way to do it using the type system or do I have to do custom validation of some sort?

Data|Errors|Meta|ExtensionMember doesn’t cut it ????