Question: nullable and enum

Hey,

I am hoping to get clarification on the following:

When the nullable and enum keywords are used together, which takes precedence?

i.e.

type: string
nullable: true
enum:
  - one
  - two

propertyA = null

When propertyA is validated against the definition. Should the result be:

1. true, since the it’s nullable
2. false, because null is not part of the enum
3. something else?

[handrews]

@EvanCarroll you realize OAS is not a C++ code generation specification, right? Anything about mapping OAS to C++ code is going to be specific to your tooling. OAS says what will and won’t validate as a JSON/YAML/etc. instance. That doesn’t always map cleanly to every programming language, and it’s up to code generators to decide what to do with those scenarios.

nullable: True, in the presence of a type field, means that a JSON null is valid in addition to whatever type (plus constraints from other keywords including enum) the schema allows That’s it. That’s all OAS says. If a value fails against the enum constraint, then it doesn’t matter what the other keywords in the schema do, it’s already failed. OAS does not say anything about constructors, or the subtleties of null values vs typing systems in different languages. That is is outside of the scope of the spec.

[handrews]

@richardwhiuk if you want to forbid null while using an enum, you need to either remove null from the enum or set type: string so that the nullable: false takes effect. Without type, nullable has no effect (in OAS 3.0.3, and it may not be implemented consistently since it was ambiguous in 3.0.0-3.0.2). This is part of why nullable is gone in OAS 3.1.