no-nullable

Id

@azure-tools/typespec-azure-core/no-nullable

Use ? for optional properties.

Properties are most often not nullable but optional. Do not use | null to specify that a property is nullable. Instead, use the ? operator to indicate that a property is optional.

Impact

• Area: API, SDK

A nullable property is usually a mistake where an optional property was intended.

❌ Incorrect

model Pet {
  id: string;
  owner: string | null;
}

✅ Correct

model Pet {
  id: string;
  owner?: string;
}

Suppression

Suppress only when required to match an existing API; otherwise use an optional property.