Add --example=<github-url> to create-next-app

packages/create-next-app/create-app.ts

@@ -5,7 +5,14 @@ import makeDir from 'make-dir'
 import os from 'os'
 import path from 'path'
 
-import { downloadAndExtractExample, hasExample } from './helpers/examples'
+import {
+  hasExample,
+  hasRepo,
+  getRepoInfo,
+  downloadAndExtractExample,
+  downloadAndExtractRepo,
+  RepoInfo,
+} from './helpers/examples'
 import { tryGitInit } from './helpers/git'
 import { install } from './helpers/install'
 import { isFolderEmpty } from './helpers/is-folder-empty'
@@ -16,20 +23,69 @@ export async function createApp({
   appPath,
   useNpm,
   example,
+  examplePath,
 }: {
   appPath: string
   useNpm: boolean
   example?: string
+  examplePath?: string
 }) {
+  let repoInfo: RepoInfo | undefined
+
   if (example) {
-    const found = await hasExample(example)
-    if (!found) {
-      console.error(
-        `Could not locate an example named ${chalk.red(
-          `"${example}"`
-        )}. Please check your spelling and try again.`
-      )
-      process.exit(1)
+    let repoUrl: URL | undefined
+
+    try {
+      repoUrl = new URL(example)
+    } catch (error) {
+      if (error.code !== 'ERR_INVALID_URL') {
+        console.error(error)
+        process.exit(1)
+      }
+    }
+
+    if (repoUrl) {
+      if (repoUrl.origin !== 'https://github.com') {
+        console.error(
+          `Invalid URL: ${chalk.red(
+            `"${example}"`
+          )}. Only GitHub repositories are supported. Please use a GitHub URL and try again.`
+        )
+        process.exit(1)
+      }
+
+      repoInfo = getRepoInfo(repoUrl, examplePath)
+
+      if (!repoInfo) {
+        console.error(
+          `Found invalid GitHub URL: ${chalk.red(
+            `"${example}"`
+          )}. Please fix the URL and try again.`
+        )
+        process.exit(1)
+      }
+
+      const found = await hasRepo(repoInfo)
+
+      if (!found) {
+        console.error(
+          `Could not locate the repository for ${chalk.red(
+            `"${example}"`
+          )}. Please check that the repository exists and try again.`
+        )
+        process.exit(1)
+      }
+    } else {
+      const found = await hasExample(example)
+
+      if (!found) {
+        console.error(
+          `Could not locate an example named ${chalk.red(
+            `"${example}"`
+          )}. Please check your spelling and try again.`
+        )
+        process.exit(1)
+      }
     }
   }
 
@@ -53,13 +109,23 @@ export async function createApp({
   process.chdir(root)
 
   if (example) {
-    console.log(
-      `Downloading files for example ${chalk.cyan(
-        example
-      )}. This might take a moment.`
-    )
-    console.log()
-    await downloadAndExtractExample(root, example)
+    if (repoInfo) {
+      console.log(
+        `Downloading files from repo ${chalk.cyan(
+          example
+        )}. This might take a moment.`
+      )
+      console.log()
+      await downloadAndExtractRepo(root, repoInfo)
+    } else {
+      console.log(
+        `Downloading files for example ${chalk.cyan(
+          example
+        )}. This might take a moment.`
+      )
+      console.log()
+      await downloadAndExtractExample(root, example)
+    }
 
     // Copy our default `.gitignore` if the application did not provide one
     const ignorePath = path.join(root, '.gitignore')

packages/create-next-app/helpers/examples.ts

@@ -2,20 +2,69 @@ import got from 'got'
 import promisePipe from 'promisepipe'
 import tar from 'tar'
 
-export async function hasExample(name: string): Promise<boolean> {
-  const res = await got(
+export type RepoInfo = {
+  username: string
+  name: string
+  branch: string
+  filePath: string
+}
+
+export async function isUrlOk(url: string) {
+  const res = await got(url).catch(e => e)
+  return res.statusCode === 200
+}
+
+export function getRepoInfo(
+  url: URL,
+  examplePath?: string
+): RepoInfo | undefined {
+  const [, username, name, t, _branch, ...file] = url.pathname.split('/')
+  const filePath = examplePath ? examplePath.replace(/^\//, '') : file.join('/')
+  // If examplePath is available, the branch name takes the entire path
+  const branch = examplePath
+    ? `${_branch}/${file.join('/')}`.replace(new RegExp(`/${filePath}|/$`), '')
+    : _branch
+
+  if (username && name && branch && t === 'tree') {
+    return { username, name, branch, filePath }
+  }
+}
+
+export function hasRepo({ username, name, branch, filePath }: RepoInfo) {
+  const contentsUrl = `https://api.github.com/repos/${username}/${name}/contents`
+  const packagePath = `${filePath ? `/${filePath}` : ''}/package.json`
+
+  return isUrlOk(contentsUrl + packagePath + `?ref=${branch}`)
+}
+
+export function hasExample(name: string): Promise<boolean> {
+  return isUrlOk(
     `https://api.github.com/repos/zeit/next.js/contents/examples/${encodeURIComponent(
       name
     )}/package.json`
-  ).catch(e => e)
-  return res.statusCode === 200
+  )
+}
+
+export function downloadAndExtractRepo(
+  root: string,
+  { username, name, branch, filePath }: RepoInfo
+): Promise<void> {
+  return promisePipe(
+    got.stream(
+      `https://codeload.github.com/${username}/${name}/tar.gz/${branch}`
+    ),
+    tar.extract(
+      { cwd: root, strip: filePath ? filePath.split('/').length + 1 : 1 },
+      [`${name}-${branch}${filePath ? `/${filePath}` : ''}`]
+    )
+  )
 }
 
-export async function downloadAndExtractExample(
+export function downloadAndExtractExample(
   root: string,
   name: string
 ): Promise<void> {
-  return await promisePipe(
+  return promisePipe(
     got.stream('https://codeload.github.com/zeit/next.js/tar.gz/canary'),
     tar.extract({ cwd: root, strip: 3 }, [`next.js-canary/examples/${name}`])
   )

packages/create-next-app/index.ts

@@ -21,8 +21,23 @@ const program = new Commander.Command(packageJson.name)
   })
   .option('--use-npm')
   .option(
-    '-e, --example <example-path>',
-    'an example to bootstrap the app with'
+    '-e, --example <name>|<github-url>',
+    `
+
+  An example to bootstrap the app with. You can use an example name
+  from the official Next.js repo or a GitHub URL. The URL can use
+  any branch and/or subdirectory
+`
+  )
+  .option(
+    '--example-path <path-to-example>',
+    `
+
+  In a rare case, your GitHub URL might contain a branch name with
+  a slash (e.g. bug/fix-1) and the path to the example (e.g. foo/bar).
+  In this case, you must specify the path to the example separately:
+  --example-path foo/bar
+`
   )
   .allowUnknownOption()
   .parse(process.argv)
@@ -89,6 +104,7 @@ async function run() {
     example:
       (typeof program.example === 'string' && program.example.trim()) ||
       undefined,
+    examplePath: program.examplePath,
   })
 }
 

test/integration/create-next-app/index.test.js

@@ -81,4 +81,77 @@ describe('create next app', () => {
       fs.existsSync(path.join(cwd, projectName, '.gitignore'))
     ).toBeTruthy()
   })
+
+  it('should allow example with GitHub URL', async () => {
+    const projectName = 'github-app'
+    const res = await run(
+      projectName,
+      '--example',
+      'https://github.com/zeit/next-learn-demo/tree/master/1-navigate-between-pages'
+    )
+
+    expect(res.exitCode).toBe(0)
+    expect(
+      fs.existsSync(path.join(cwd, projectName, 'package.json'))
+    ).toBeTruthy()
+    expect(
+      fs.existsSync(path.join(cwd, projectName, 'pages/index.js'))
+    ).toBeTruthy()
+    expect(
+      fs.existsSync(path.join(cwd, projectName, 'pages/about.js'))
+    ).toBeTruthy()
+    expect(
+      fs.existsSync(path.join(cwd, projectName, '.gitignore'))
+    ).toBeTruthy()
+  })
+
+  it('should allow example with GitHub URL and example-path', async () => {
+    const projectName = 'github-example-path'
+    const res = await run(
+      projectName,
+      '--example',
+      'https://github.com/zeit/next-learn-demo/tree/master',
+      '--example-path',
+      '1-navigate-between-pages'
+    )
+
+    expect(res.exitCode).toBe(0)
+    expect(
+      fs.existsSync(path.join(cwd, projectName, 'package.json'))
+    ).toBeTruthy()
+    expect(
+      fs.existsSync(path.join(cwd, projectName, 'pages/index.js'))
+    ).toBeTruthy()
+    expect(
+      fs.existsSync(path.join(cwd, projectName, 'pages/about.js'))
+    ).toBeTruthy()
+    expect(
+      fs.existsSync(path.join(cwd, projectName, '.gitignore'))
+    ).toBeTruthy()
+  })
+
+  it('should use --example-path over the file path in the GitHub URL', async () => {
+    const projectName = 'github-example-path-2'
+    const res = await run(
+      projectName,
+      '--example',
+      'https://github.com/zeit/next-learn-demo/tree/master/1-navigate-between-pages',
+      '--example-path',
+      '1-navigate-between-pages'
+    )
+
+    expect(res.exitCode).toBe(0)
+    expect(
+      fs.existsSync(path.join(cwd, projectName, 'package.json'))
+    ).toBeTruthy()
+    expect(
+      fs.existsSync(path.join(cwd, projectName, 'pages/index.js'))
+    ).toBeTruthy()
+    expect(
+      fs.existsSync(path.join(cwd, projectName, 'pages/about.js'))
+    ).toBeTruthy()
+    expect(
+      fs.existsSync(path.join(cwd, projectName, '.gitignore'))
+    ).toBeTruthy()
+  })
 })