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enum-nullability-coercion

Keeps an enum's null membership consistent with whether its schema permits null.

AttributeValue
CategorySchema
MaturityPlatinum
OpenAPISwagger 2.0; OpenAPI 3.0, 3.1, 3.2
StarterOff
LenientWarning
Recommended–CompleteError

Intent​

The schema and enum should give one answer about nullability. Contradictory declarations lead validators and generators to disagree.

Flags​

  • A nullable schema whose enum omits null.
  • A non-nullable schema whose enum contains null.
  • A non-nullable enum containing only null.

Nullability may come from the version-appropriate schema form, including nullable: true or a type containing null.

Does not flag​

A nullable enum containing null, or a non-nullable enum without it.

See it fail​

State:
  type: string
  nullable: true
  enum: [active, inactive]

Diagnostic: Enum values must contain null if the enum is marked nullable

Fix it​

State:
  type: string
  nullable: true
  enum: [active, inactive, null]

Alternatively, remove nullability when null is not a valid value.

Configure​

profiles:
  default:
    rules:
      extends: [recommended]
      override:
        enum-nullability-coercion: warn

Nearby: oas30-enum-null-coercion, nullable-type-sibling.