fix: validate eventTypeId is number in API v1 bookings endpoint (#22433)

* fix: validate eventTypeId is number in API v1 bookings endpoint

- Add validation to return 400 when eventTypeId is string instead of integer
- Prevents string values from reaching Prisma and causing 500 errors
- Follows existing validation patterns in the codebase
- Add test case to verify string eventTypeId returns 400 Bad Request

Co-Authored-By: keith@cal.com <keithwillcode@gmail.com>

* test: add focused test for eventTypeId validation

- Create separate test file for string eventTypeId validation
- Ensures validation logic is properly tested without being blocked by pre-existing issues
- Addresses cubic-dev-ai bot feedback about skipped tests
- Both string and number eventTypeId scenarios are tested

Co-Authored-By: keith@cal.com <keithwillcode@gmail.com>

* fix: improve eventTypeId validation to only check defined values

- Only validate eventTypeId when it's defined and not a number
- Prevents interference with schema validation for missing/undefined values
- Maintains 400 error response for string eventTypeId as required
- Fixes test compatibility issues while preserving validation logic

Co-Authored-By: keith@cal.com <keithwillcode@gmail.com>

* test: move eventTypeId validation test outside of skipped block

- Create dedicated test block for eventTypeId validation
- Remove duplicate test from skipped block
- Ensures validation logic is properly tested
- Addresses PR feedback from keithwillcode

Co-Authored-By: keith@cal.com <keithwillcode@gmail.com>

* cleanup: remove duplicate eventTypeId validation test file

- Remove apps/api/v1/test/lib/bookings/eventTypeId-validation.test.ts
- Tests are now properly located in _post.test.ts outside skipped block
- Addresses PR feedback from keithwillcode about duplicate tests

Co-Authored-By: keith@cal.com <keithwillcode@gmail.com>

---------

Co-authored-by: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

apps/api/v1/pages/api/bookings/_post.ts

@@ -222,6 +222,13 @@ async function handler(req: NextApiRequest) {
   };
   if (isSystemWideAdmin) userId = req.body.userId || userId;
 
+  if (req.body.eventTypeId !== undefined && typeof req.body.eventTypeId !== "number") {
+    throw new HttpError({
+      statusCode: 400,
+      message: "Bad request, eventTypeId must be a number",
+    });
+  }
+
   if (isOrganizationOwnerOrAdmin) {
     const accessibleUsersIds = await getAccessibleUsers({
       adminUserId: userId,

apps/api/v1/test/lib/bookings/_post.test.ts

@@ -25,6 +25,44 @@ vi.mock("@calcom/lib/server/i18n", () => {
   };
 });
 
+describe("POST /api/bookings - eventTypeId validation", () => {
+  test("String eventTypeId should return 400", async () => {
+    const { req, res } = createMocks<CustomNextApiRequest, CustomNextApiResponse>({
+      method: "POST",
+      body: {
+        eventTypeId: "invalid-string",
+      },
+    });
+
+    await handler(req, res);
+
+    expect(res._getStatusCode()).toBe(400);
+    expect(JSON.parse(res._getData())).toEqual(
+      expect.objectContaining({
+        message: "Bad request, eventTypeId must be a number",
+      })
+    );
+  });
+
+  test("Number eventTypeId should not trigger validation error", async () => {
+    const { req, res } = createMocks<CustomNextApiRequest, CustomNextApiResponse>({
+      method: "POST",
+      body: {
+        eventTypeId: 123,
+      },
+    });
+
+    await handler(req, res);
+
+    const statusCode = res._getStatusCode();
+    const responseData = JSON.parse(res._getData());
+
+    if (statusCode === 400) {
+      expect(responseData.message).not.toBe("Bad request, eventTypeId must be a number");
+    }
+  });
+});
+
 describe.skipIf(true)("POST /api/bookings", () => {
   describe("Errors", () => {
     test("Missing required data", async () => {