Add a property resultSegments in lroMetadata to show the downstream how to get the final result of a lro

.chronus/changes/fix-2072-2025-0-21-15-49-15.md

@@ -0,0 +1,7 @@
+---
+changeKind: feature
+packages:
+  - "@azure-tools/typespec-client-generator-core"
+---
+
+Add a `resultSegments` property to `SdkLroServiceFinalResponse` and deprecate `resultPath` property. Add a `resultSegments` property to `SdkMethodResponse`.

packages/typespec-client-generator-core/src/interfaces.ts

@@ -586,6 +586,11 @@ export interface SdkMethodResponse {
   kind: "method";
   type?: SdkType;
   resultPath?: string; // if exists, tells you how to get from the service response to the method response.
+  /**
+   * An array of properties to fetch {result} from the {response} model. Note that this property is available only in some LRO patterns.
+   * Temporarily this is not enabled for paging now.
+   */
+  resultSegments?: SdkModelPropertyType[];
 }
 
 export interface SdkServiceResponse {
@@ -726,8 +731,14 @@ export interface SdkLroServiceFinalResponse {
   envelopeResult: SdkModelType;
   /** Meaningful result type */
   result: SdkModelType;
-  /** Property path to fetch {result} from {envelopeResult}. Note that this property is available only in some LRO patterns. */
+  /**
+   * Property path to fetch {result} from {envelopeResult}. Note that this property is available only in some LRO patterns.
+   *
+   * @deprecated This property will be removed in future releases. Use `resultSegments` for synthesized property information.
+   */
   resultPath?: string;
+  /** An array of properties to fetch {result} from the {envelopeResult} model. Note that this property is available only in some LRO patterns. */
+  resultSegments?: SdkModelPropertyType[];
 }
 
 export interface SdkLroServiceMethod<TServiceOperation extends SdkServiceOperation>

packages/typespec-client-generator-core/src/package.ts

@@ -28,6 +28,7 @@ import {
 } from "./decorators.js";
 import { getSdkHttpOperation, getSdkHttpParameter } from "./http.js";
 import {
+  SdkBodyModelPropertyType,
   SdkClient,
   SdkClientType,
   SdkEndpointParameter,
@@ -36,6 +37,7 @@ import {
   SdkHttpOperation,
   SdkInitializationType,
   SdkLroPagingServiceMethod,
+  SdkLroServiceFinalResponse,
   SdkLroServiceMetadata,
   SdkLroServiceMethod,
   SdkMethod,
@@ -313,8 +315,11 @@ function getSdkLroServiceMethod<TServiceOperation extends SdkServiceOperation>(
 
   basicServiceMethod.response.type = metadata.finalResponse?.result;
 
+  // eslint-disable-next-line @typescript-eslint/no-deprecated
   basicServiceMethod.response.resultPath = metadata.finalResponse?.resultPath;
 
+  basicServiceMethod.response.resultSegments = metadata.finalResponse?.resultSegments;
+
   return diagnostics.wrap({
     ...basicServiceMethod,
     kind: "lro",
@@ -344,18 +349,7 @@ function getServiceMethodLroMetadata(
   return {
     __raw: rawMetadata,
     finalStateVia: rawMetadata.finalStateVia,
-    finalResponse:
-      rawMetadata.finalEnvelopeResult !== undefined && rawMetadata.finalEnvelopeResult !== "void"
-        ? {
-            envelopeResult: diagnostics.pipe(
-              getClientTypeWithDiagnostics(context, rawMetadata.finalEnvelopeResult),
-            ) as SdkModelType,
-            result: diagnostics.pipe(
-              getClientTypeWithDiagnostics(context, rawMetadata.finalResult as Model),
-            ) as SdkModelType,
-            resultPath: rawMetadata.finalResultPath,
-          }
-        : undefined,
+    finalResponse: getFinalResponse(),
     finalStep:
       rawMetadata.finalStep !== undefined ? { kind: rawMetadata.finalStep.kind } : undefined,
     pollingStep: {
@@ -364,6 +358,41 @@ function getServiceMethodLroMetadata(
       ) as SdkModelType,
     },
   };
+
+  function getFinalResponse(): SdkLroServiceFinalResponse | undefined {
+    if (
+      rawMetadata?.finalEnvelopeResult === undefined ||
+      rawMetadata.finalEnvelopeResult === "void"
+    ) {
+      return undefined;
+    }
+
+    const envelopeResult = diagnostics.pipe(
+      getClientTypeWithDiagnostics(context, rawMetadata.finalEnvelopeResult),
+    ) as SdkModelType;
+    const result = diagnostics.pipe(
+      getClientTypeWithDiagnostics(context, rawMetadata.finalResult as Model),
+    ) as SdkModelType;
+    const resultPath = rawMetadata.finalResultPath;
+    // find the property inside the envelope result using the final result path
+    let sdkProperty: SdkBodyModelPropertyType | undefined = undefined;
+    for (const property of envelopeResult.properties) {
+      if (property.__raw === undefined || property.kind !== "property") {
+        continue;
+      }
+      if (property.__raw?.name === resultPath) {
+        sdkProperty = property;
+        break;
+      }
+    }
+
+    return {
+      envelopeResult,
+      result,
+      resultPath,
+      resultSegments: sdkProperty !== undefined ? [sdkProperty] : undefined,
+    };
+  }
 }
 
 function getSdkMethodResponse(

packages/typespec-client-generator-core/test/methods/lro.test.ts

@@ -110,6 +110,7 @@ describe("typespec-client-generator-core: long running operation metadata", () =
         );
         strictEqual(roundtripModel.serializationOptions.json?.name, "User");
         assert.isUndefined(metadata.finalResponse?.resultPath);
+        assert.isUndefined(metadata.finalResponse?.resultSegments);
       });
 
       it("LongRunningResourceDelete", async () => {
@@ -235,6 +236,11 @@ describe("typespec-client-generator-core: long running operation metadata", () =
         strictEqual(metadata.finalResponse?.envelopeResult, pollingModel);
         strictEqual(metadata.finalResponse?.result, returnModel);
         strictEqual(metadata.finalResponse?.resultPath, "result");
+        // find the property
+        const resultProperty = pollingModel.properties.find((p) => p.name === "result");
+        ok(metadata.finalResponse?.resultSegments);
+        strictEqual(metadata.finalResponse?.resultSegments[0], resultProperty);
+
         assert.isTrue(
           hasFlag(pollingModel.usage, UsageFlags.LroFinalEnvelope),
           "the polling model here is also the final envelope model, it should have the usage of LroFinalEnvelope",
@@ -326,13 +332,94 @@ describe("typespec-client-generator-core: long running operation metadata", () =
         strictEqual(metadata.finalResponse?.envelopeResult, pollingModel);
         strictEqual(metadata.finalResponse?.result, returnModel);
         strictEqual(metadata.finalResponse?.resultPath, "result");
+        // find the property
+        const resultProperty = pollingModel.properties.find((p) => p.name === "result");
+        ok(metadata.finalResponse?.resultSegments);
+        strictEqual(metadata.finalResponse?.resultSegments[0], resultProperty);
         assert.isTrue(
           hasFlag(pollingModel.usage, UsageFlags.LroFinalEnvelope),
           "the polling model here is also the final envelope model, it should have the usage of LroFinalEnvelope",
         );
       });
     });
     describe("Custom LRO", () => {
+      it("@lroResult with client name and/or encoded name", async () => {
+        await runner.compileWithBuiltInAzureCoreService(`
+        op CustomLongRunningOperation<
+          TParams extends TypeSpec.Reflection.Model,
+          TResponse extends TypeSpec.Reflection.Model
+        > is Foundations.Operation<
+          TParams,
+          AcceptedResponse & {
+            @pollingLocation
+            @header("Operation-Location")
+            operationLocation: ResourceLocation<TResponse>;
+          }
+        >;
+
+        @resource("resources")
+        model Resource {
+          @visibility("read")
+          id: string;
+
+          @key
+          @visibility("read")
+          name: string;
+
+          description?: string;
+          type: string;
+        }
+
+        // no "result" property
+        model OperationDetails {
+          @doc("Operation ID")
+          @key
+          @visibility("read", "create")
+          id: uuid;
+
+          status: Azure.Core.Foundations.OperationState;
+          error?: Azure.Core.Foundations.Error;
+
+          @lroResult
+          @clientName("longRunningResult")
+          @encodedName("application/json", "lro_result")
+          result?: Resource;
+        }
+
+        @doc("Response")
+        @route("/response")
+        interface ResponseOp {
+
+          @route("/lro-result")
+          lroInvalidResult is CustomLongRunningOperation<
+            {
+              @body request: Resource;
+            },
+            OperationDetails
+          >;
+        }
+        `);
+
+        const client = runner.context.sdkPackage.clients[0];
+        const method = client.methods[0];
+        strictEqual(method.kind, "clientaccessor");
+        const resourceOpClient = method.response;
+        const lroMethod = resourceOpClient.methods[0];
+        strictEqual(lroMethod.kind, "lro");
+        const lroMetadata = lroMethod.lroMetadata;
+        ok(lroMetadata);
+        strictEqual(lroMetadata.finalResponse?.resultPath, "result"); // this is showing the typespec name, which is neither client name nor wire name
+        // find the model
+        const envelopeResult = runner.context.sdkPackage.models.find(
+          (m) => m.name === "OperationDetails",
+        );
+        const resultProperty = envelopeResult?.properties.find(
+          (p) => p.name === "longRunningResult",
+        );
+        ok(lroMetadata.finalResponse?.resultSegments);
+        strictEqual(resultProperty, lroMetadata.finalResponse?.resultSegments[0]);
+      });
+
       it("@pollingOperation", async () => {
         await runner.compileWithVersionedService(`
         @resource("analyze/jobs")
@@ -789,6 +876,7 @@ describe("typespec-client-generator-core: long running operation metadata", () =
       strictEqual(metadata.finalResponse?.envelopeResult, roundtripModel);
       strictEqual(metadata.finalResponse?.result, roundtripModel);
       assert.isUndefined(metadata.finalResponse.resultPath);
+      assert.isUndefined(metadata.finalResponse.resultSegments);
     });
 
     it("ArmResourceDeleteWithoutOkAsync", async () => {