Polymorphic Resource

Danger

This sample is for grandfathered specs only and should not be used for new specs.

Sample configuration for polymorphic-resource in legacy.

main.tsp

import "@typespec/http";
import "@typespec/rest";
import "@typespec/versioning";
import "@azure-tools/typespec-azure-core";
import "@azure-tools/typespec-azure-resource-manager";
import "./proxy.tsp";
import "./extension.tsp";

using Versioning;
using Azure.ResourceManager;

/** Contoso Resource Provider management API. */
#suppress "@azure-tools/typespec-azure-resource-manager/missing-operations-endpoint" ""
@armProviderNamespace
@service(#{ title: "ContosoProviderHubClient" })
@versioned(Versions)
namespace Microsoft.ContosoProviderHub;

/** Contoso API versions */
enum Versions {
  /** 2021-10-01-preview version */
  @armCommonTypesVersion(Azure.ResourceManager.CommonTypes.Versions.v5)
  `2025-10-01-preview`,
}

/** Standard operation list */
interface Operations extends Azure.ResourceManager.Operations {}

extension.tsp

import "@typespec/http";
import "@typespec/rest";
import "@typespec/versioning";
import "@azure-tools/typespec-azure-core";
import "@azure-tools/typespec-azure-resource-manager";

using Azure.ResourceManager;

namespace Microsoft.ContosoProviderHub;

/** A ContosoProviderHub resource */
#suppress "@azure-tools/typespec-azure-core/no-legacy-usage" "For sample purpose"
model Cost is Azure.ResourceManager.Legacy.DiscriminatedExtensionResource {
  ...ResourceNameParameter<Cost>;
}

/** The rp-specific properties of the cost */
model CapitalProperties {
  /** The amount of capital */
  amount?: float64;

  ...DefaultProvisioningStateProperty;
}

/** The properties of an expense */
model ExpenseProperties {
  /** The amount of the expense */
  amount?: float64;

  /** The duration of the expense */
  duration?: duration;

  ...DefaultProvisioningStateProperty;
}

/** Salaried employee */
model Capital extends Cost {
  kind: "capital";
  properties: CapitalProperties;
}

/** Hourly employee */
model Expense extends Cost {
  kind: "expense";
  properties: ExpenseProperties;
}

@armResourceOperations
interface Costs<Parent extends Foundations.SimpleResource> {
  get is Extension.Read<Parent, Cost>;
  list is Extension.ListByTarget<Parent, Cost>;
}
@armResourceOperations
interface Scopes extends Costs<Extension.ScopeParameter> {}
@armResourceOperations
interface Tenants extends Costs<Extension.Tenant> {}
@armResourceOperations
interface Subscriptions extends Costs<Extension.Subscription> {}
@armResourceOperations
interface ManagementGroups extends Costs<Extension.ManagementGroup> {}

proxy.tsp

import "@typespec/http";
import "@typespec/rest";
import "@typespec/versioning";
import "@azure-tools/typespec-azure-core";
import "@azure-tools/typespec-azure-resource-manager";

using Azure.ResourceManager;

namespace Microsoft.ContosoProviderHub;

/** A ContosoProviderHub resource */
#suppress "@azure-tools/typespec-azure-core/no-legacy-usage" "For sample purpose"
@subscriptionResource
model Room is Azure.ResourceManager.Legacy.DiscriminatedProxyResource {
  ...ResourceNameParameter<Room>;
}

@doc("The rp-specific properties of the room")
model ConferenceRoomProperties {
  /** The number of occupants */
  capacity?: int32;

  /** The city of current residence */
  city?: string;

  ...DefaultProvisioningStateProperty;
}

/** The properties of an office */
model OfficeProperties {
  /** The number of desks in the office */
  desks?: int32;

  /** The city of current residence */
  city?: string;

  ...DefaultProvisioningStateProperty;
}

/** Salaried employee */
model ConferenceRoom extends Room {
  kind: "conference";
  properties: ConferenceRoomProperties;
}

/** Hourly employee */
model Office extends Room {
  kind: "office";
  properties: OfficeProperties;
}

@armResourceOperations
interface Rooms {
  get is ArmResourceRead<Room>;
  list is ArmResourceListByParent<Room>;
}