Expose setOperation

.chronus/changes/expose-set-operation-id-2026-1-11-14-48-58.md

@@ -0,0 +1,8 @@
+---
+# Change versionKind to one of: internal, fix, dependencies, feature, deprecation, breaking
+changeKind: fix
+packages:
+  - "@typespec/openapi"
+---
+
+[API] Expose `setOperationId` 

packages/openapi/src/decorators.ts

@@ -28,7 +28,20 @@ import { validateAdditionalInfoModel, validateIsUri } from "./helpers.js";
 import { createStateSymbol, OpenAPIKeys, reportDiagnostic } from "./lib.js";
 import { AdditionalInfo, ExtensionKey, ExternalDocs } from "./types.js";
 
-const operationIdsKey = createStateSymbol("operationIds");
+export const [
+  /**
+   * Returns operationId set via the `@operationId` decorator or `undefined`
+   */
+  getOperationId,
+
+  /**
+   * Set a specific operation ID programmatically. Equivalent of using `@operationId` decorator.
+   * @param program TypeSpec Program
+   * @param entity Operation to set ID for
+   * @param opId Operation ID
+   */
+  setOperationId,
+] = useStateMap<Operation, string>(createStateSymbol("operationIds"));
 /**
  * Set a specific operation ID.
  * @param context Decorator Context
@@ -40,16 +53,9 @@ export const $operationId: OperationIdDecorator = (
   entity: Operation,
   opId: string,
 ) => {
-  context.program.stateMap(operationIdsKey).set(entity, opId);
+  setOperationId(context.program, entity, opId);
 };
 
-/**
- * Returns operationId set via the `@operationId` decorator or `undefined`
- */
-export function getOperationId(program: Program, entity: Operation): string | undefined {
-  return program.stateMap(operationIdsKey).get(entity);
-}
-
 const openApiExtensionKey = createStateSymbol("openApiExtension");
 
 /** {@inheritdoc ExtensionDecorator} */

packages/openapi/src/index.ts

@@ -19,6 +19,7 @@ export {
   resolveInfo,
   setExtension,
   setInfo,
+  setOperationId,
 } from "./decorators.js";
 export {
   checkDuplicateTypeName,

packages/openapi/test/decorators.test.ts

@@ -12,32 +12,6 @@ import {
 import { Tester } from "./test-host.js";
 
 describe("openapi: decorators", () => {
-  describe("@operationId", () => {
-    it("emit diagnostic if use on non operation", async () => {
-      const diagnostics = await Tester.diagnose(`
-        @operationId("foo")
-        model Foo {}
-      `);
-
-      expectDiagnostics(diagnostics, {
-        code: "decorator-wrong-target",
-        message:
-          "Cannot apply @operationId decorator to Foo since it is not assignable to Operation",
-      });
-    });
-
-    it("emit diagnostic if operation id is not a string", async () => {
-      const diagnostics = await Tester.diagnose(`
-        @operationId(123)
-        op foo(): string;
-      `);
-
-      expectDiagnostics(diagnostics, {
-        code: "invalid-argument",
-      });
-    });
-  });
-
   describe("@extension", () => {
     it("apply extension on model", async () => {
       const { program, Foo } = await Tester.compile(t.code`

packages/openapi/test/decorators/operation-id.test.ts

@@ -0,0 +1,69 @@
+import { expectDiagnostics, t } from "@typespec/compiler/testing";
+import { expect, it } from "vitest";
+import { getOperationId, setOperationId } from "../../src/decorators.js";
+import { Tester } from "../test-host.js";
+
+it("emit diagnostic if use on non operation", async () => {
+  const diagnostics = await Tester.diagnose(`
+    @operationId("foo")
+    model Foo {}
+  `);
+
+  expectDiagnostics(diagnostics, {
+    code: "decorator-wrong-target",
+    message: "Cannot apply @operationId decorator to Foo since it is not assignable to Operation",
+  });
+});
+
+it("emit diagnostic if operation id is not a string", async () => {
+  const diagnostics = await Tester.diagnose(`
+    @operationId(123)
+    op foo(): string;
+  `);
+
+  expectDiagnostics(diagnostics, {
+    code: "invalid-argument",
+  });
+});
+
+it("set operation id via decorator", async () => {
+  const { program, foo } = await Tester.compile(t.code`
+    @operationId("myCustomId")
+    op ${t.op("foo")}(): string;
+  `);
+
+  expect(getOperationId(program, foo)).toEqual("myCustomId");
+});
+
+it("getOperationId returns undefined when no operation id is set", async () => {
+  const { program, foo } = await Tester.compile(t.code`
+    op ${t.op("foo")}(): string;
+  `);
+
+  expect(getOperationId(program, foo)).toEqual(undefined);
+});
+
+it("setOperationId function sets operation id programmatically", async () => {
+  const { program, foo } = await Tester.compile(t.code`
+    op ${t.op("foo")}(): string;
+  `);
+
+  expect(getOperationId(program, foo)).toEqual(undefined);
+
+  setOperationId(program, foo, "programmaticId");
+
+  expect(getOperationId(program, foo)).toEqual("programmaticId");
+});
+
+it("setOperationId function can override decorator-set operation id", async () => {
+  const { program, foo } = await Tester.compile(t.code`
+    @operationId("decoratorId")
+    op ${t.op("foo")}(): string;
+  `);
+
+  expect(getOperationId(program, foo)).toEqual("decoratorId");
+
+  setOperationId(program, foo, "overrideId");
+
+  expect(getOperationId(program, foo)).toEqual("overrideId");
+});