feat(openapi-fetch): Allow returning Response from onRequest callback #2091

p-dubovitsky · 2025-01-04T14:33:55Z

Changes

This PR closes #2072 by adding ability to return Response from onRequest middleware hook. This allows middleware to short-circuit the request chain by returning a response directly, which is useful for cases such as deduplicating or caching responses to avoid unnecessary network requests.

How to Review

Please check that:

Early Response from onRequest properly skips remaining middleware chain
Test coverage is sufficient
Documentation clearly explains new functionality

Key implementation details:

No changes to existing middleware behavior
When Response is returned:
- The request is not sent to the server
- Subsequent onRequest handlers are skipped
- onResponse handlers are skipped

Checklist

Unit tests updated
docs/ updated (if necessary)
pnpm run update:examples run (only applicable for openapi-typescript)

netlify · 2025-01-04T14:33:57Z

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changeset-bot · 2025-01-04T14:33:59Z

🦋 Changeset detected

Latest commit: 5a38436

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 3 packages

Name	Type
openapi-fetch	Patch
openapi-react-query	Patch
swr-openapi	Patch

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gzm0

Nice! (and sorry for the somewhat tardy review).

Mostly nits on tests, and one doubt in the example that we probably should address.

gzm0 · 2025-01-24T11:10:52Z

docs/openapi-fetch/middleware-auth.md

+  onResponse({ request, response }) {
+    if (response.ok) {
+      const key = getCacheKey(request);
+      cache.set(key, response);


Are you sure we do not need to clone the response here? The response we return is (probably) going to be consumed by the caller.

IIUC, clone() will throw if the response has already been used:

clone() throws a TypeError if the response body has already been used.

(https://developer.mozilla.org/en-US/docs/Web/API/Response/clone)

Yes, I think you're right. Thanks for your consideration!

gzm0 · 2025-01-24T11:13:01Z

packages/openapi-fetch/src/index.js

+              response = result;
+              break;
+            } else {
+              throw new Error("onRequest: must return new Request() or Response() when modifying the request");


I think this error message was wrong an now it feels even more wrong :-/ (IIUC you must not return new Request() but mutate the request in place and return it, unclear to me why returning the request is even necessary...).

Probably not blocking for this PR, but a fix would be appreciated.

Yeah I’m keen to just remove this (not necessarily in this PR, just in general); this is not true in some cases. It was meant to provide a friendlier error for folks, but I actually think just letting the platform surface the error is more helpful, rather than us getting in the way

I'm not sure I understood you correctly. Do you want to throw an error without a message or something else?

gzm0 · 2025-01-24T13:06:23Z

packages/openapi-fetch/test/middleware/middleware.test.ts

+
+test("can return response directly from onRequest", async () => {
+  const customResponse = Response.json({});
+  const client = createObservedClient<paths>();


Suggested change

const client = createObservedClient<paths>();

const client = createObservedClient<paths>({}, () => throw new Error("unexpected call to fetch"));

This way, we make sure we really do not call fetch.

gzm0 · 2025-01-24T13:07:57Z

packages/openapi-fetch/test/middleware/middleware.test.ts

+
+test("skips subsequent onRequest handlers when response is returned", async () => {
+  let onRequestCalled = false;
+  const customResponse = Response.json({});


Nit: Inline below? You don't actually need the reference for this test.

gzm0 · 2025-01-24T13:08:06Z

packages/openapi-fetch/test/middleware/middleware.test.ts

+
+test("skips onResponse handlers when response is returned from onRequest", async () => {
+  let onResponseCalled = false;
+  const customResponse = Response.json({});


Same: Inline below?

gzm0 · 2025-01-24T13:08:16Z

packages/openapi-fetch/test/middleware/middleware.test.ts

Nice tests!

StrongerMyself · 2025-03-07T11:52:00Z

Please update the openapi-fetch package with this functionality. The latest available version in npm is 0.13.4, does not have ‘Early Response’

npm error notarget No matching version found for openapi-fetch@^0.13.5.

https://www.npmjs.com/package/openapi-fetch?activeTab=versions

StrongerMyself · 2025-03-07T12:57:29Z

docs/openapi-fetch/middleware-auth.md

+    if (response.ok) {
+      const key = getCacheKey(request);
+      cache.set(key, response.clone());
+    }


Here you must return return response.clone(), otherwise the request body will be read on line 222 in index.js and repeated requests will be rejected with an error

Are you sure? The response in the cache is cloned.

I say this only from looking at the code, if you have tried this and it fails, well, then it fails :)

PR to fix the example in this case is very much appreciated.

I am using nextjs 15 (server-side requests). At some point response becomes bodyUsage=true, maybe it is related to the environment - nodesj. Most likely your example works for client-side code, but not for server-side code. I'm not sure how best to flesh out the documentation. In my case, I save data(as text), headers and statuses in Map.

const cache = new Map<string, string>(); const getCacheKey = (request: Request) => `${request.method}:${request.url}`; const cacheMiddleware: Middleware = { onRequest({ request }) { const key = getCacheKey(request); const cached = cache.get(key); if (cached) { // Return cached response, skipping actual request and remaining middleware chain const response = new Response(cached); return response; } }, async onResponse({ request, response }) { if (response.ok) { const key = getCacheKey(request); const responseBody = await response.clone().text(); cache.set(key, responseBody); } } };

TY for the example. Unfortunately, without more understanding of what is going on here, from the maintainers side, I don't think we have a strong enough signal to take this further.

If you would like, please file a bug with this, and investigation can proceed there. However, please understand that you will be expected to produce a reproducible example that relies on a (standard) fetch implementation only (of course that needs to run in browsers and Node.js, but no SSR magic, just free-standing code).

p-dubovitsky requested a review from a team as a code owner January 4, 2025 14:33

p-dubovitsky requested a review from gzm0 January 4, 2025 14:33

feat(openapi-fetch): Allow returning Response from onRequest callback

fad2a50

p-dubovitsky force-pushed the early-response branch from 3532cdc to fad2a50 Compare January 4, 2025 14:56

gzm0 requested changes Jan 24, 2025

View reviewed changes

feat(openapi-fetch): Allow returning Response from onRequest callback

5a38436

p-dubovitsky force-pushed the early-response branch from 27648e2 to 5a38436 Compare February 13, 2025 15:46

duncanbeevers added the openapi-fetch Relevant to the openapi-fetch library label Feb 15, 2025

p-dubovitsky requested a review from gzm0 February 17, 2025 16:30

gzm0 approved these changes Feb 19, 2025

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gzm0 merged commit ebe56f3 into openapi-ts:main Feb 19, 2025
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openapi-ts-bot mentioned this pull request Feb 19, 2025

[ci] release #2164

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StrongerMyself reviewed Mar 7, 2025

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openapi-ts-bot mentioned this pull request Mar 14, 2025

[ci] release #2201

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feat(openapi-fetch): Allow returning Response from onRequest callback #2091

feat(openapi-fetch): Allow returning Response from onRequest callback #2091

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	const client = createObservedClient<paths>();
	const client = createObservedClient<paths>({}, () => throw new Error("unexpected call to fetch"));

feat(openapi-fetch): Allow returning Response from onRequest callback #2091

feat(openapi-fetch): Allow returning Response from onRequest callback #2091

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p-dubovitsky commented Jan 4, 2025 • edited Loading

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