no-multiple-discriminator

Id

@azure-tools/typespec-azure-core/no-multiple-discriminator

Classes should have at most one discriminator.

Using a nested polymophic relationship is not allowed in Azure services. Most JSON serializers and deserializers do not support this feature.

Impact

• Area: SDK, API

Multiple discriminators are not supported by SDKs, nor by Swagger without extensions.

❌ Incorrect

@discriminator("fishtype")
model Fish {
  fishtype: string;
}

@discriminator("sharktype")
model Shark extends Fish {
  fishtype: "shark";
  sharktype: string;
}

model WhiteShark extends Shark {
  sharktype: "white";
}

✅ Correct

@discriminator("fishtype")
model Fish {
  fishtype: string;
}

model Shark extends Fish {
  fishtype: "shark";
}

model WhiteShark extends Fish {
  fishtype: "white-shark";
}

Suppression

Suppress only with SDK approval. Use a single discriminator and refactor additional discriminators onto child or sibling properties.