## Bug
fixes#37106
Please note that, as for `pages/` the `src/middleware` file is ignored when `/middleware` is present.
## How to test
1. Rebuild next.js `pnpm build`
2. Run dedicated tests: `pnpm testheadless --testPathPattern middleware-src/`
This PR deprecates declaring a middleware under `pages` in favour of the project root naming it after `middleware` instead of `_middleware`. This is in the context of having a simpler execution model for middleware and also ships some refactor work. There is a ton of a code to be simplified after this deprecation but I think it is best to do it progressively.
With this PR, when in development, we will **fail** whenever we find a nested middleware but we do **not** include it in the compiler so if the project is using it, it will no longer work. For production we will **fail** too so it will not be possible to build and deploy a deprecated middleware. The error points to a page that should also be reviewed as part of **documentation**.
Aside from the deprecation, this migrates all middleware tests to work with a single middleware. It also splits tests into multiple folders to make them easier to isolate and work with. Finally it ships some small code refactor and simplifications.
List all exports for internal path module to avoid import destruction is breaking with typescript.
#### Prev
```js
import pathMod from '../isomorphic/path'
const { join, resolve } = pathMod
```
#### Now
```js
import { join, resolve } from '../isomorphic/path'
```
x-ref: #36190
x-ref: #31506
* Move nodejs ptah module usage to next-server, keep base-server and web-server headless for `'path'`
* Use a native module `path` for nodejs runtime and `path` polyfill for edge runtime
This PR adds support for [Middleware as per RFC ](https://github.com/vercel/next.js/discussions/29750).
## Feature
- [ ] Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.
- [ ] Errors have helpful link attached, see `contributing.md`
## Documentation / Examples
- [ ] Make sure the linting passes
This PR introduces an improved developer experience when `next lint` is run for the first time.
### Current behavior
`eslint-config-next` is a required package that must be installed before proceeding with `next lint` or `next build`:
Although this has helped many developers start using the new ESLint config, this has also resulted in a few issues:
- Users are required to install the full config (`eslint-config-next`) even if they do not use it or use the Next.js plugin directly (`eslint-plugin-next`).
- #26348
- There's some confusion on why `eslint-config-next` needs to be installed or how it should be used instead of `eslint-plugin-next`.
- #26574
- #26475
- #26438
### New behavior
Instead of enforcing `eslint-config-next` as a required package, this PR prompts the user by asking what config they would like to start. This happens when `next lint` is run for the first time **and** if no ESLint configuration is detected in the application.
<img src="https://user-images.githubusercontent.com/12476932/124331177-e1668a80-db5c-11eb-8915-38d3dc20f5d4.gif" width="800" />
- The CLI will take care of installing `eslint` or `eslint-config-next` if either is not already installed
- Users now have the option to choose between a strict configuration (`next/core-web-vitals`) or just the base configuration (`next`)
- For users that decide to create their own ESLint configuration, or already have an existing one, **installing `eslint-config-next` will not be a requirement for `next lint` or `next build` to run**. A warning message will just show if the Next.js ESLint plugin is not detected in an ESLint config.
<img width="682" alt="Screen Shot 2021-06-25 at 3 02 12 PM" src="https://user-images.githubusercontent.com/12476932/123473329-6cc4a680-d5c6-11eb-9a57-d5c0b89a2732.png">
---
In addition, this PR also:
- Fixes#26348
- Updates documentation to make it more clear what approach to take for new and existing ESLint configurations
This adds generating a static 500 status page when a `pages/500.js` file is added similar to how we handle generating static 404 pages when `pages/404.js` is present. This allows showing a customized error page when a 500 error occurs in an optimal way.
By popular request, this pull request adds support for returning `fallback: 'blocking'` from `getStaticPaths`.
This new mode will cause unknown paths to be rendered on-demand ("SSR") without the static (placeholder) fallback.
This feature is **currently experimental and should not be used in production yet**. It's currently flagged behind `unstable_`:
```
fallback: 'unstable_blocking'
```
TODO:
- [x] Next.js tests
- [ ] Add Vercel support
- [ ] Vercel tests
---
Fixes#15637
* Rename unstable GSP revalidate field
* Update error message
* Tweak error message some more
* Apply suggestions from code review
Co-Authored-By: Joe Haddad <joe.haddad@zeit.co>
Co-authored-by: Joe Haddad <joe.haddad@zeit.co>
* Make sure to not show pages/404 GIP error from _app having GIP
* Add error for getStaticProps in pages/404 too
* Add support for getStaticProps in pages/404
* Update test
* Rename getServerProps to getServerSideProps
* Remove unstable_ prefix from new methods
* Add error when legacy methods are detected
* Add legacy methods for babel transform
* Add unstable_getServerSideProps also
* Apply suggestions from code review
Co-Authored-By: Joe Haddad <joe.haddad@zeit.co>
* Update types import
Co-authored-by: Joe Haddad <timer150@gmail.com>
* Implement experimental pages/404.js for custom 404 page
* Make sure to show error for getInitialProps in pages/404 in dev mode also
* Update routes-manifest tests for new value
* Make sure page404 is boolean in routes-manifest
* Rename variables for consistency
* Make sure to only use 404 page for 404 error
* Add support for unstable_getServerProps
* Apply suggestions from review
* Add no-cache header and update types
* Revert sharing of load-components type
* Add catchall test and update routes-manifest field
* Update header check
* Update to pass query for getServerProps data requests
* Update to not cache getServerProps requests
* Rename server side props identifier
* Update to nest props for getServerProps
* Add no-cache header in serverless-loader also
* Update to throw error for mixed SSG/serverProps earlier
* Add comment explaining params chosing in serverless-loader
* Update invalidKeysMsg to return a string and inline throwing
* Inline throwing mixed SSG/serverProps error
* Update setting cache header in serverless-loader
* Add separate getServerData method in router
* Update checkIsSSG -> isDataIdentifier
* Refactor router getData back to ternary
* Apply suggestions to build/index.ts
* drop return
* De-dupe extra escape regex
* Add param test
* initial commit for SPRv2
* Add initial SPR cache handling
* update SPR handling
* Implement SPR handling in render
* Update tests, handle caching with serverless next
start, add TODOs, and update manifest generating
* Handle no prerender-manifest from not being used
* Fix url.parse error
* Apply suggestions from code review
Co-Authored-By: Joe Haddad <joe.haddad@zeit.co>
* Replace set with constants in next-page-config
* simplify sprStatus.used
* Add error if getStaticProps is used with getInitialProps
* Remove stale TODO
* Update revalidate values in SPR cache for non-seeded routes
* Apply suggestions from code review
* Remove concurrency type
* Rename variable for clarity
* Add copying prerender files during export
* Add comment for clarity
* Fix exporting
* Update comment
* Add additional note
* Rename variable
* Update to not re-export SPR pages from build
* Hard navigate when fetching data fails
* Remove default extension
* Add brackets
* Add checking output files to prerender tests
* Adjust export move logic
* Clarify behavior of export aggregation
* Update variable names for clarity
* Update tests
* Add comment
* s/an oxymoron/contradictory/
* rename
* Extract error case
* Add tests for exporting SPR pages and update
/_next/data endpoint to end with .json
* Relocate variable
* Adjust route building
* Rename to unstable
* Rename unstable_getStaticParams
* Fix linting
* Only add this when a data request
* Update prerender data tests
* s/isServerless/isLikeServerless/
* Don't rely on query for `next start` in serverless mode
* Rename var
* Update renderedDuringBuild check
* Add test for dynamic param with bracket
* Fix serverless next start handling
* remove todo
* Adjust comment
* Update calculateRevalidate
* Remove cache logic from render.tsx
* Remove extra imports
* Move SPR cache logic to next-server
* Remove old isDynamic prop
* Add calling App getInitialProps for SPR pages
* Update revalidate logic
* Add isStale to SprCacheValue
* Update headers for SPR
* add awaiting pendingRevalidation
* Dont return null for revalidation render
* Adjust logic
* Be sure to remove coalesced render
* Fix data for serverless
* Create a method coalescing utility
* Remove TODO
* Extract send payload helper
* Wrap in-line
* Move around some code
* Add tests for de-duping and revalidating
* Update prerender manifest test
* Match public files priority in dev
* Remove un-needed old public file handling
* Run public file priority test for non-dev also
* Make sure to enable publicDirectory
* Add checking for conflicting pages in dev and during build
* Add error for public dir middleware conflict
* Add err.sh for _next conflict
* Move up public dir conflict checking
* Only run _next conflict check in dev when path contains it
* Run prettier over packages/**/*.js
* Run prettier over packages/**/*.ts
* Run prettier over examples
* Remove tslint
* Run prettier over examples
* Run prettier over all markdown files
* Run prettier over json files
