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Add Import trace for requested module when it fails to resolve (verce…
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…l#27840)

Co-authored-by: Steven <[email protected]>
Co-authored-by: kodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>
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3 people authored Aug 9, 2021
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151 changes: 151 additions & 0 deletions errors/module-not-found.md
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@@ -0,0 +1,151 @@
# Module Not Found

#### Why This Error Occurred

A module not found error can occur for many different reasons:

- The module you're trying to import is not installed in your dependencies
- The module you're trying to import is in a different directory
- The module you're trying to import has a different casing
- The module you're trying to import uses Node.js specific modules, for example `dns`, outside of `getStaticProps` / `getStaticPaths` / `getServerSideProps`

#### Possible Ways to Fix It

##### The module you're trying to import is not installed in your dependencies

When importing a module from [npm](https://npmjs.com) this module has to be installed locally.

For example when importing the `swr` package:

```js
import useSWR from 'swr'
```

The `swr` module has to be installed using a package manager.

- When using `npm`: `npm install swr`
- When using `yarn`: `yarn add swr`

##### The module you're trying to import is in a different directory

Make sure that the path you're importing refers to the right directory and file.

##### The module you're trying to import has a different casing

Make sure the casing of the file is correct.

Example:

```js
// components/MyComponent.js
export default function MyComponent() {
return <h1>Hello</h1>
}
```

```js
// pages/index.js
// Note how `components/MyComponent` exists but `Mycomponent` without the capital `c` is imported
import MyComponent from '../components/Mycomponent'
```

Incorrect casing will lead to build failures on case-sensitive environments like most Linux-based continuous integration and can cause issues with Fast Refresh.

##### The module you're trying to import uses Node.js specific modules

`getStaticProps`, `getStaticPaths`, and `getServerSideProps` allow for using modules that can only run in the Node.js environment. This allows you to do direct database queries or reading data from Redis to name a few examples.

The tree shaking only runs on top level pages, so it can't be relied on in separate React components.

You can verify the tree shaking on [next-code-elimination.vercel.app](https://next-code-elimination.vercel.app/).

Example of correctly tree shaken code:

```js
// lib/redis.js
import Redis from 'ioredis'

const redis = new Redis(process.env.REDIS_URL)

export default redis
```

```js
// pages/index.js
import redis from '../lib/redis'

export async function getStaticProps() {
const message = await redis.get('message')
return {
message,
}
}

export default function Home({ message }) {
return <h1>{message}</h1>
}
```

Example of code that would break:

```js
// lib/redis.js
import Redis from 'ioredis'

const redis = new Redis(process.env.REDIS_URL)

export default redis
```

```js
// pages/index.js
// Redis is a Node.js specific library that can't run in the browser
// Trying to use it in code that runs on both Node.js and the browser will result in a module not found error for modules that ioredis relies on
// If you run into such an error it's recommended to move the code to `getStaticProps` or `getServerSideProps` as those methods guarantee that the code is only run in Node.js.
import redis from '../lib/redis'
import { useEffect, useState } from 'react'

export default function Home() {
const [message, setMessage] = useState()
useEffect(() => {
redis.get('message').then((result) => {
setMessage(result)
})
}, [])
return <h1>{message}</h1>
}
```

Example of code that would break:

```js
// lib/redis.js
import Redis from 'ioredis'

// Modules that hold Node.js-only code can't also export React components
// Tree shaking of getStaticProps/getStaticPaths/getServerSideProps is ran only on page files
const redis = new Redis(process.env.REDIS_URL)

export function MyComponent() {
return <h1>Hello</h1>
}

export default redis
```

```js
// pages/index.js
// In practice you'll want to refactor the `MyComponent` to be a separate file so that tree shaking ensures that specific import is not included for the browser compilation
import redis, { MyComponent } from '../lib/redis'

export async function getStaticProps() {
const message = await redis.get('message')
return {
message,
}
}

export default function Home() {
return <MyComponent />
}
```
Original file line number Diff line number Diff line change
@@ -1,9 +1,51 @@
import Chalk from 'chalk'
import { SimpleWebpackError } from './simpleWebpackError'
import { createOriginalStackFrame } from '@next/react-dev-overlay/lib/middleware'
import { isWebpack5 } from 'next/dist/compiled/webpack/webpack'
import path from 'path'

const chalk = new Chalk.constructor({ enabled: true })

// Based on https://github.com/webpack/webpack/blob/fcdd04a833943394bbb0a9eeb54a962a24cc7e41/lib/stats/DefaultStatsFactoryPlugin.js#L422-L431
/*
Copyright JS Foundation and other contributors
Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
'Software'), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:
The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
function getModuleTrace(input: any, compilation: any) {
const visitedModules = new Set()
const moduleTrace = []
let current = input.module
while (current) {
if (visitedModules.has(current)) break // circular (technically impossible, but who knows)
visitedModules.add(current)
const origin = compilation.moduleGraph.getIssuer(current)
if (!origin) break
moduleTrace.push({ origin, module: current })
current = origin
}

return moduleTrace
}

export async function getNotFoundError(
compilation: any,
input: any,
Expand Down Expand Up @@ -36,11 +78,38 @@ export async function getNotFoundError(
.replace(/ in '.*?'/, '')
.replace(/Can't resolve '(.*)'/, `Can't resolve '${chalk.green('$1')}'`)

const importTrace = () => {
if (!isWebpack5) {
return ''
}

let importTraceLine = '\nImport trace for requested module:\n'
const moduleTrace = getModuleTrace(input, compilation)

for (const { origin } of moduleTrace) {
if (!origin.resource) {
continue
}
const filePath = path.relative(
compilation.options.context,
origin.resource
)
importTraceLine += `./${filePath}\n`
}

return importTraceLine + '\n'
}

const frame = result.originalCodeFrame ?? ''

const message =
chalk.red.bold('Module not found') +
`: ${errorMessage}` +
'\n' +
result.originalCodeFrame
frame +
(frame !== '' ? '\n' : '') +
importTrace() +
'\nhttps://nextjs.org/docs/messages/module-not-found'

return new SimpleWebpackError(
`${chalk.cyan(fileName)}:${chalk.yellow(
Expand Down
88 changes: 74 additions & 14 deletions test/acceptance/ReactRefreshLogBox.dev.test.js
Original file line number Diff line number Diff line change
Expand Up @@ -705,12 +705,14 @@ test('unterminated JSX', async () => {
await cleanup()
})

test('Module not found', async () => {
const [session, cleanup] = await sandbox()

await session.patch(
'index.js',
`import Comp from 'b'
// Module trace is only available with webpack 5
if (!process.env.NEXT_PRIVATE_TEST_WEBPACK4_MODE) {
test('Module not found', async () => {
const [session, cleanup] = await sandbox()

await session.patch(
'index.js',
`import Comp from 'b'
export default function Oops() {
return (
<div>
Expand All @@ -719,23 +721,28 @@ test('Module not found', async () => {
)
}
`
)
)

expect(await session.hasRedbox(true)).toBe(true)
expect(await session.hasRedbox(true)).toBe(true)

const source = await session.getRedboxSource()
expect(source).toMatchInlineSnapshot(`
const source = await session.getRedboxSource()
expect(source).toMatchInlineSnapshot(`
"./index.js:1:0
Module not found: Can't resolve 'b'
> 1 | import Comp from 'b'
2 | export default function Oops() {
3 | return (
4 | <div>"
`)
4 | <div>
Import trace for requested module:
./pages/index.js
await cleanup()
})
https://nextjs.org/docs/messages/module-not-found"
`)

await cleanup()
})
}
test('conversion to class component (1)', async () => {
const [session, cleanup] = await sandbox()

Expand Down Expand Up @@ -1634,3 +1641,56 @@ test('_document syntax error shows logbox', async () => {
expect(await session.hasRedbox()).toBe(false)
await cleanup()
})

// Module trace is only available with webpack 5
if (!process.env.NEXT_PRIVATE_TEST_WEBPACK4_MODE) {
test('Node.js builtins', async () => {
const [session, cleanup] = await sandbox(
undefined,
new Map([
[
'node_modules/my-package/index.js',
`
const dns = require('dns')
module.exports = dns
`,
],
[
'node_modules/my-package/package.json',
`
{
"name": "my-package",
"version": "0.0.1"
}
`,
],
]),
undefined,
/ready - started server on/i
)

await session.patch(
'index.js',
`
import pkg from 'my-package'
export default function Hello() {
return (pkg ? <h1>Package loaded</h1> : <h1>Package did not load</h1>)
}
`
)
expect(await session.hasRedbox(true)).toBe(true)
expect(await session.getRedboxSource()).toMatchInlineSnapshot(`
"./node_modules/my-package/index.js:2:0
Module not found: Can't resolve 'dns'
Import trace for requested module:
./index.js
./pages/index.js
https://nextjs.org/docs/messages/module-not-found"
`)

await cleanup()
})
}

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