Allow booleans in place of any top-level schema field

[MikeRalphson]

It has been pointed out that we didn't achieve 100% JSON Schema compatibility with the release of OAS v3.1.0. JSON Schema allows spelling the schema {} as true and the schema not: {} as false.

These are currently allowed in subschemas, but not where our schema field indicates an OpenAPI schemaObject (literally of type object as expected by the metaschema for example) is allowed.

This may only be of academic interest, as it is possible to spell the empty schema either as {} as above, or by omitting the schema keyword entirely (where allowed), and the false / not: {} schema has limited utility at the top-level in OAS - but for the sake of spec. and tooling compatibility, here is this PR.

It allows the schema fields to contain booleans in the same way we used to allow schemaObject | referenceObject in v3.0.x

This PR does not touch the metaschema as it is still somewhat in flux. I propose we pick up metaschema changes in the RC / post-release phase as with previous versions.

Edit: an alternative is to add wording similar to that we had in v3.0.x

Alternatively, anywhere a Schema Object can be used, a Reference Objectboolean MAY be used in its place.

Signed-off-by: Mike Ralphson mike.ralphson@gmail.com

[karenetheridge]

Wouldn't this require updates to the metaschemas as well? specifically

$defs:
components:
type: object
properties:
schemas:
type: object
additionalProperties:
$dynamicRef: '#meta'

should change type: object to type: [ object, boolean ]

edit: actually no, the schemas themselves are one layer down, under the properties... and at the 'schema' definition, where the 'meta' dynamicAnchor is defined, we already have type: [ object, boolean ] there. So the schema is already correct; it is just the spec wording that is inconsistent with it.

[MikeRalphson]

Wouldn't this require updates to the metaschemas as well?

@karenetheridge I explicitly said...

This PR does not touch the metaschema as it is still somewhat in flux. I propose we pick up metaschema changes in the RC / post-release phase as with previous versions.

... but thank you for pointing out that the v3.1 metaschemas may be out of step with the markdown source-of-truth. Ping @jdesrosiers

[char0n]

Great, thanks for clarification! Would it be possible to explicitly mention in 3.1 that Boolean JSON Schemas are not supported as top level Schema Objects? It's kind of implied because the name of the spec object is Schema Object but, when implementing tooling it gives space for interpretation and I was actually inclined to support Boolean JSON Schemas in 3.1 tooling (as top level Schema Objects) but eventually decided not to go for it.

[MikeRalphson]

I was actually inclined to support Boolean JSON Schemas in 3.1 tooling (as top level Schema Objects) but eventually decided not to go for it.

Thanks also, @char0n for the data-point.

[jdesrosiers]

Instead of adding "| boolean" everywhere, I'd suggest just redefining "Schema Object" to include boolean. It allows the spec to only be changed in one place and is more correct (boolean schemas are a JSON Schema concept, not an OpenAPI concept).

I agree with @char0n that it's not explicitly stated in the spec that this value must be an object ("Schema Object" is a name, it's not specifying anything). Therefore, I think it's reasonable to fix this in the 3.1.1 patch rather than 3.2.0. I think it's clarifying an ambiguity, not changing a specified behavior.

[Relequestual]

For the sake of not just adding a +1 but being on record... I agree with everything @jdesrosiers said above.

[MikeRalphson]

Will replace with alternative PR on the v3.1.1-dev branch as discussed.