Handle BUILD_ID mismatch error

lib/router/index.js

@@ -1,3 +1,4 @@
+/* global window, location */
 import _Router from './router'
 
 const SingletonRouter = {
@@ -75,3 +76,11 @@ export const createRouter = function (...args) {
 
 // Export the actual Router class, which is usually used inside the server
 export const Router = _Router
+
+export function _notifyBuildIdMismatch (nextRoute) {
+  if (SingletonRouter.onAppUpdated) {
+    SingletonRouter.onAppUpdated(nextRoute)
+  } else {
+    location.href = nextRoute
+  }
+}

lib/router/router.js

@@ -6,6 +6,7 @@ import evalScript from '../eval-script'
 import shallowEquals from '../shallow-equals'
 import PQueue from '../p-queue'
 import { loadGetInitialProps, getLocationOrigin } from '../utils'
+import { _notifyBuildIdMismatch } from './'
 
 // Add "fetch" polyfill for older browsers
 if (typeof window !== 'undefined') {
@@ -75,7 +76,7 @@ export default class Router extends EventEmitter {
       data,
       props,
       error
-    } = await this.getRouteInfo(route, pathname, query)
+    } = await this.getRouteInfo(route, pathname, query, as)
 
     if (error && error.cancelled) {
       this.emit('routeChangeError', error, as)
@@ -116,7 +117,7 @@ export default class Router extends EventEmitter {
       data,
       props,
       error
-    } = await this.getRouteInfo(route, pathname, query)
+    } = await this.getRouteInfo(route, pathname, query, url)
 
     if (error && error.cancelled) {
       this.emit('routeChangeError', error, url)
@@ -162,7 +163,7 @@ export default class Router extends EventEmitter {
     this.emit('routeChangeStart', as)
     const {
       data, props, error
-    } = await this.getRouteInfo(route, pathname, query)
+    } = await this.getRouteInfo(route, pathname, query, as)
 
     if (error && error.cancelled) {
       this.emit('routeChangeError', error, as)
@@ -189,11 +190,16 @@ export default class Router extends EventEmitter {
     }
   }
 
-  async getRouteInfo (route, pathname, query) {
+  async getRouteInfo (route, pathname, query, as) {
     const routeInfo = {}
 
     try {
-      const { Component, err, jsonPageRes } = routeInfo.data = await this.fetchComponent(route)
+      routeInfo.data = await this.fetchComponent(route, as)
+      if (!routeInfo.data) {
+        return null
+      }
+
+      const { Component, err, jsonPageRes } = routeInfo.data
       const ctx = { err, pathname, query, jsonPageRes }
       routeInfo.props = await this.getInitialProps(Component, ctx)
     } catch (err) {
@@ -229,7 +235,7 @@ export default class Router extends EventEmitter {
     return this.prefetchQueue.add(() => this.fetchRoute(route))
   }
 
-  async fetchComponent (route) {
+  async fetchComponent (route, as) {
     let data = this.components[route]
     if (data) return data
 
@@ -240,6 +246,15 @@ export default class Router extends EventEmitter {
 
     const jsonPageRes = await this.fetchRoute(route)
     const jsonData = await jsonPageRes.json()
+
+    if (jsonData.buildIdMismatch) {
+      _notifyBuildIdMismatch(as)
+
+      const error = Error('Abort due to BUILD_ID mismatch')
+      error.cancelled = true
+      throw error
+    }
+
     const newData = {
       ...loadComponent(jsonData),
       jsonPageRes

readme.md

@@ -310,6 +310,7 @@ Here's a list of supported events:
 - `routeChangeStart(url)` - Fires when a route starts to change
 - `routeChangeComplete(url)` - Fires when a route changed completely
 - `routeChangeError(err, url)` - Fires when there's an error when changing routes
+- `appUpdated(nextRoute)` - Fires when switching pages and there's a new version of the app
 
 > Here `url` is the URL shown in the browser. If you call `Router.push(url, as)` (or similar), then the value of `url` will be `as`.
 
@@ -337,6 +338,17 @@ Router.onRouteChangeError = (err, url) => {
 }
 ```
 
+If you change a route while in between a new deployment, we can't navigate the app via client side. We need to do a full browser navigation. We do it automatically for you.
+
+But you can customize that via `Route.onAppUpdated` event like this:
+
+```js
+Router.onAppUpdated = (nextUrl) => {
+  // persist the local state
+  location.href = nextUrl
+}
+```
+
 ### Prefetching Pages
 
 <p><details>

server/index.js

@@ -81,19 +81,30 @@ export default class Server {
       },
 
       '/_next/:buildId/main.js': async (req, res, params) => {
-        this.handleBuildId(params.buildId, res)
+        if (!this.handleBuildId(params.buildId, res)) {
+          throwBuildIdMismatchError()
+        }
+
         const p = join(this.dir, '.next/main.js')
         await this.serveStatic(req, res, p)
       },
 
       '/_next/:buildId/commons.js': async (req, res, params) => {
-        this.handleBuildId(params.buildId, res)
+        if (!this.handleBuildId(params.buildId, res)) {
+          throwBuildIdMismatchError()
+        }
+
         const p = join(this.dir, '.next/commons.js')
         await this.serveStatic(req, res, p)
       },
 
       '/_next/:buildId/pages/:path*': async (req, res, params) => {
-        this.handleBuildId(params.buildId, res)
+        if (!this.handleBuildId(params.buildId, res)) {
+          res.setHeader('Content-Type', 'application/json')
+          res.end(JSON.stringify({ buildIdMismatch: true }))
+          return
+        }
+
         const paths = params.path || ['index']
         const pathname = `/${paths.join('/')}`
         await this.renderJSON(req, res, pathname)
@@ -277,14 +288,13 @@ export default class Server {
   }
 
   handleBuildId (buildId, res) {
-    if (this.dev) return
+    if (this.dev) return true
     if (buildId !== this.renderOpts.buildId) {
-      const errorMessage = 'Build id mismatch!' +
-        'Seems like the server and the client version of files are not the same.'
-      throw new Error(errorMessage)
+      return false
     }
 
     res.setHeader('Cache-Control', 'max-age=365000000, immutable')
+    return true
   }
 
   getCompilationError (page) {
@@ -298,3 +308,7 @@ export default class Server {
     if (p) return errors.get(p)[0]
   }
 }
+
+function throwBuildIdMismatchError () {
+  throw new Error('BUILD_ID Mismatched!')
+}

test/integration/basic/test/misc.js

@@ -1,6 +1,6 @@
 /* global describe, test, expect */
 
-export default function ({ app }) {
+export default function (context) {
   describe('Misc', () => {
     test('finishes response', async () => {
       const res = {
@@ -9,7 +9,7 @@ export default function ({ app }) {
           this.finished = true
         }
       }
-      const html = await app.renderToHTML({}, res, '/finish-response', {})
+      const html = await context.app.renderToHTML({}, res, '/finish-response', {})
       expect(html).toBeFalsy()
     })
   })