feat(pathRewrite): add 'res' and 'options' to custom pathRewrite function by chimurai · Pull Request #1247 · chimurai/http-proxy-middleware

chimurai · 2026-05-24T18:28:59Z

closes #854

Summary by CodeRabbit

New Features
- Custom pathRewrite callbacks now receive response and options context (in addition to path and request), allowing rewrites to depend on response state or middleware options.
Documentation
- Updated pathRewrite docs and examples (sync/async) to show full function signatures and usage.
- Clarified that the response argument is undefined for WebSocket upgrade flows.

…tion

coderabbitai · 2026-05-24T18:29:12Z

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 7808c077-acbb-422b-8757-a308ffbd3d3e

📥 Commits

Reviewing files that changed from the base of the PR and between b5e175f and 026897b.

📒 Files selected for processing (1)

src/types.ts

📝 Walkthrough

Walkthrough

The PR extends pathRewrite to pass (path, req, res, options) to rewrite callbacks, updates TypeScript types to include a TRes generic, re-parameters createPathRewriter, wires the rewriter through the middleware, adds tests verifying res/options are passed, and updates docs/changelog.

Changes

pathRewrite Signature Enhancement

Layer / File(s)	Summary
Type contract and signature `src/types.ts`	`PathRewriteConfig` adds `TRes` generic; rewrite functions may accept `(path, req, res?, options?)` and return `string
Path rewriter module `src/path-rewriter.ts`	`createPathRewriter` now accepts `PathRewriteConfig<TReq, TRes>` and imports `ServerResponse`; validator signatures updated to the new generic shape.
Middleware integration `src/http-proxy-middleware.ts`	Middleware stores a `pathRewriter` typed for `TReq,TRes`, constructs it with both generics, and `applyPathRewrite` now accepts/invokes the rewriter with `(req.url, req, res, options)`.
Test coverage `test/unit/path-rewriter.spec.ts`, `test/e2e/path-rewriter.spec.ts`, `test/types.spec.ts`	Unit test asserts custom rewriter is called with `(path, req, res, options)`; E2E test captures `res` and `options` inside `pathRewrite`; type tests updated for the new signature and `res` usage.
User documentation `CHANGELOG.md`, `README.md`, `recipes/pathRewrite.md`	Changelog, README, and recipe examples updated to show the extended `pathRewrite(path, req, res, options)` signature and note that `res` is undefined during WebSocket upgrade flows.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

chimurai/http-proxy-middleware#1197: Overlaps on path-rewriter typing and structure; this PR extends that earlier type parameterization to include response context.
chimurai/http-proxy-middleware#1214: Both PRs affect applyPathRewrite invocation and callback typing around request/url handling in the middleware path-rewrite pipeline.

Poem

🐰 A rabbit hops through rewrite nights,
Passing res and options in soft lights.
Locals whisper where paths once bent,
Async hops await your intent.
Cheers to clearer hops and tiny delights!

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 33.33% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely summarizes the main change: adding 'res' and 'options' parameters to the custom pathRewrite function, which aligns with the core objective of the PR.
Linked Issues check	✅ Passed	The PR fully addresses issue `#854` by passing the response object and options into the custom pathRewrite function, enabling access to res.locals as requested in the feature request.
Out of Scope Changes check	✅ Passed	All changes are directly related to the stated objective of adding res and options parameters to pathRewrite; no out-of-scope modifications were introduced.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

📝 Generate docstrings

Create stacked PR
Commit on current branch

🧪 Generate unit tests (beta)

Create PR with unit tests
Commit unit tests in branch pathRewrite-support-res-and-option

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

pkg-pr-new · 2026-05-24T18:29:51Z

npm i https://pkg.pr.new/http-proxy-middleware@1247

commit: 026897b

coveralls · 2026-05-24T18:30:45Z

coverage: 94.656%. remained the same — pathRewrite-support-res-and-option into master

coderabbitai

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@src/types.ts`:
- Around line 76-82: The type for the async pathRewrite callback currently
forces Promise<string>, preventing valid no-op rewrites; update the callback
return type(s) so async handlers can return Promise<string | undefined> (and
ensure the synchronous variant also allows string | undefined) — change
occurrences of Promise<string> to Promise<string | undefined> for the
pathRewrite function type (and string to string | undefined where applicable) so
typings match runtime behavior that treats non-string/undefined as “no rewrite”.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

Push a commit to this branch (recommended)
Create a new PR with the fixes

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 626fac3a-b051-4726-9fbe-bffb35dfe498

📥 Commits

Reviewing files that changed from the base of the PR and between 3ab96d8 and b5e175f.

📒 Files selected for processing (9)

CHANGELOG.md
README.md
recipes/pathRewrite.md
src/http-proxy-middleware.ts
src/path-rewriter.ts
src/types.ts
test/e2e/path-rewriter.spec.ts
test/types.spec.ts
test/unit/path-rewriter.spec.ts

feat(pathRewrite): add 'res' and 'options' to custom pathRewrite func…

b5e175f

…tion

coderabbitai Bot reviewed May 24, 2026

View reviewed changes

Comment thread src/types.ts Outdated

chimurai added this to the v4.1 milestone May 24, 2026

fix(pathRewriter): align Promise return type

026897b

chimurai merged commit 39a47ab into master May 24, 2026
26 checks passed

chimurai deleted the pathRewrite-support-res-and-option branch May 24, 2026 18:44

chimurai mentioned this pull request Jun 21, 2026

feat: remove bypass option from proxy configuration webpack/webpack-dev-server#5641

Merged

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

feat(pathRewrite): add 'res' and 'options' to custom pathRewrite function#1247

feat(pathRewrite): add 'res' and 'options' to custom pathRewrite function#1247
chimurai merged 2 commits into
masterfrom
pathRewrite-support-res-and-option

chimurai commented May 24, 2026 •

edited by coderabbitai Bot

Loading

Uh oh!

coderabbitai Bot commented May 24, 2026 •

edited

Loading

Walkthrough

Changes

Estimated code review effort

Possibly related PRs

Poem

❌ Failed checks (1 warning)

Uh oh!

pkg-pr-new Bot commented May 24, 2026 •

edited

Loading

Uh oh!

coveralls commented May 24, 2026 •

edited

Loading

Uh oh!

coderabbitai Bot left a comment

Uh oh!

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

Conversation

chimurai commented May 24, 2026 • edited by coderabbitai Bot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Summary by CodeRabbit

Uh oh!

coderabbitai Bot commented May 24, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Walkthrough

Changes

Estimated code review effort

Possibly related PRs

Poem

❌ Failed checks (1 warning)

Uh oh!

pkg-pr-new Bot commented May 24, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

coveralls commented May 24, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

coderabbitai Bot left a comment

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

chimurai commented May 24, 2026 •

edited by coderabbitai Bot

Loading

coderabbitai Bot commented May 24, 2026 •

edited

Loading

pkg-pr-new Bot commented May 24, 2026 •

edited

Loading

coveralls commented May 24, 2026 •

edited

Loading