chore: cleanup, pass responseFn in decode error function

Author: starfy84

packages/express-wrapper/src/request.ts

@@ -97,9 +97,15 @@ const createNamedFunction = <F extends (...args: any) => void>(
 export const onDecodeError: OnDecodeErrorFn = (errs, _req, res) => {
   const validationErrors = PathReporter.failure(errs);
   const validationErrorMessage = validationErrors.join('\n');
-  res.writeHead(400, { 'Content-Type': 'application/json' });
-  res.write(JSON.stringify({ error: validationErrorMessage }));
-  res.end();
+  return {
+    response: validationErrorMessage,
+    statusCode: 400,
+    responseFn: () => {
+      res.writeHead(400, { 'Content-Type': 'application/json' });
+      res.write(JSON.stringify({ error: validationErrorMessage }));
+      res.end();
+    },
+  };
 };
 
 export const onEncodeError: OnEncodeErrorFn = (err, _req, res) => {

packages/typed-express-router/src/errors.ts

@@ -7,11 +7,14 @@ import { OnDecodeErrorFn } from './types';
 export function defaultOnDecodeError(
   errs: Errors,
   _req: express.Request,
-  _res: express.Response,
+  res: express.Response,
 ): ReturnType<OnDecodeErrorFn> {
   const validationErrors = PathReporter.failure(errs);
   const validationErrorMessage = validationErrors.join('\n');
-  return { response: validationErrorMessage, statusCode: 400 };
+  const responseFn = () => {
+    res.status(400).json({ error: validationErrorMessage }).end();
+  };
+  return { response: validationErrorMessage, statusCode: 400, responseFn };
 }
 
 export function defaultOnEncodeError(

packages/typed-express-router/src/index.ts

@@ -163,8 +163,12 @@ export function wrapRouter<Spec extends ApiSpec>(
         pipe(
           req.decoded,
           E.getOrElseW((errs) => {
-            const error = (onDecodeError ?? onDecodeError)(errs, req, res);
-            recordSpanDecodeError(decodeSpan, error.response, error.statusCode);
+            const { response, statusCode } = (options?.onDecodeError ?? onDecodeError)(
+              errs,
+              req,
+              res,
+            );
+            recordSpanDecodeError(decodeSpan, response, statusCode);
           }),
         );
         endSpan(decodeSpan);
@@ -200,10 +204,12 @@ export function wrapRouter<Spec extends ApiSpec>(
           req.decoded,
           E.matchW(
             (errs) => {
-              const { response, statusCode } = (
-                options?.onDecodeError ?? onDecodeError
-              )(errs, req, res);
-              res.status(statusCode).json(response).end();
+              const { responseFn } = (options?.onDecodeError ?? onDecodeError)(
+                errs,
+                req,
+                res,
+              );
+              responseFn();
             },
             (value) => {
               req.decoded = value;

packages/typed-express-router/src/types.ts

@@ -28,7 +28,7 @@ export type OnDecodeErrorFn = (
   errs: t.Errors,
   req: express.Request,
   res: express.Response,
-) => { response: Json; statusCode: number };
+) => { response: Json; statusCode: number; responseFn: () => void };
 
 export type OnEncodeErrorFn = (
   err: unknown,
@@ -45,13 +45,12 @@ export type AfterEncodedResponseSentFn = (
 
 export type UncheckedWrappedRouteOptions = {
   onEncodeError?: OnEncodeErrorFn;
+  onDecodeError?: OnDecodeErrorFn;
   afterEncodedResponseSent?: AfterEncodedResponseSentFn;
   routeAliases?: string[];
 };
 
-export type WrappedRouteOptions = UncheckedWrappedRouteOptions & {
-  onDecodeError?: OnDecodeErrorFn;
-};
+export type WrappedRouteOptions = UncheckedWrappedRouteOptions;
 
 export type WrappedRouterOptions = express.RouterOptions & WrappedRouteOptions;
 

packages/typed-express-router/test/server.test.ts

@@ -361,8 +361,14 @@ test('should return a 400 when request fails to decode', async () => {
 
 test('should invoke custom decode error function', async () => {
   const router = createRouter(TestApiSpec, {
-    onDecodeError: (_errs, _req, _res) => {
-      return { response: 'Custom decode error', statusCode: 400 };
+    onDecodeError: (_errs, _req, res) => {
+      return {
+        response: 'Custom decode error',
+        statusCode: 400,
+        responseFn: () => {
+          res.status(400).json('Custom decode error').end();
+        },
+      };
     },
   });
 
@@ -390,8 +396,14 @@ test('should invoke custom decode error function', async () => {
 
 test('should invoke per-route custom decode error function', async () => {
   const router = createRouter(TestApiSpec, {
-    onDecodeError: (_errs, _req, _res) => {
-      return { response: 'Top-level decode error', statusCode: 400 };
+    onDecodeError: (_errs, _req, res) => {
+      return {
+        response: 'Top-level decode error',
+        statusCode: 400,
+        responseFn: () => {
+          res.status(400).json('Top-level decode error').end();
+        },
+      };
     },
   });
 
@@ -403,8 +415,14 @@ test('should invoke per-route custom decode error function', async () => {
       },
     ],
     {
-      onDecodeError: (_errs, _req, _res) => {
-        return { response: 'Route decode error', statusCode: 400 };
+      onDecodeError: (_errs, _req, res) => {
+        return {
+          response: 'Route decode error',
+          statusCode: 400,
+          responseFn: () => {
+            res.status(400).json('Route decode error').end();
+          },
+        };
       },
       routeAliases: ['/helloNoPathParams'],
     },

packages/typed-express-router/test/telemetry.test.ts

@@ -175,7 +175,17 @@ beforeEach(async () => {
   const router = createRouter(TestApiSpec);
 
   router.get('hello.world', [GetHelloWorld]);
-  router.put('hello.world', [CreateHelloWorld]);
+  router.put('hello.world', [CreateHelloWorld], {
+    onDecodeError: (_errs, _req, res) => {
+      return {
+        response: 'Custom Decode Error',
+        statusCode: 400,
+        responseFn: () => {
+          res.status(400).json({ error: 'Custom Decode Error' });
+        },
+      };
+    },
+  });
   router.get('hello.world.bad', [GetHelloWorldBad]);
 
   app.use(router);
@@ -359,10 +369,18 @@ test('should capture decode errors', async () => {
     );
     assert.ok(decodeSpan, 'Encode span not found');
     assert.strictEqual(decodeSpan?.attributes?.[ApiTsAttributes.API_TS_PATH], '/hello');
+
     const errorEvents = decodeSpan.events.filter((event) => {
       return event['name'] === 'exception';
     });
     assert.ok(errorEvents.length > 0, 'Expected at least 1 error event');
+
+    assert.ok(
+      errorEvents.find(
+        (event) => event.attributes?.['exception.message'] === '"Custom Decode Error"',
+      ),
+      'Expected custom decode reporter message',
+    );
   });
 });