Refactor next-server some for easier page checking (#9671)

* De-dupe pagesManifest

* Update handleApiRequest a bit

* Simplify handleApiRequest a bit

* Update packages/next/next-server/server/next-server.ts
Co-authored-by: NJoe Haddad <joe.haddad@zeit.co>

packages/next/next-server/server/api-utils.ts

-import { IncomingMessage } from 'http'
+import { IncomingMessage, ServerResponse } from 'http'
 import { NextApiResponse, NextApiRequest } from '../lib/utils'
 import { Stream } from 'stream'
 import getRawBody from 'raw-body'
@@ -11,12 +11,15 @@ export type NextApiRequestCookies = { [key: string]: string }
 export type NextApiRequestQuery = { [key: string]: string | string[] }
 
 export async function apiResolver(
-  req: NextApiRequest,
-  res: NextApiResponse,
+  req: IncomingMessage,
+  res: ServerResponse,
   params: any,
   resolverModule: any,
   onError?: ({ err }: { err: any }) => Promise<void>
 ) {
+  const apiReq = req as NextApiRequest
+  const apiRes = res as NextApiResponse
+
   try {
     let config: PageConfig = {}
     let bodyParser = true
@@ -33,32 +36,32 @@ export async function apiResolver(
       }
     }
     // Parsing of cookies
-    setLazyProp({ req }, 'cookies', getCookieParser(req))
+    setLazyProp({ req: apiReq }, 'cookies', getCookieParser(req))
     // Parsing query string
-    setLazyProp({ req, params }, 'query', getQueryParser(req))
+    setLazyProp({ req: apiReq, params }, 'query', getQueryParser(req))
     // // Parsing of body
     if (bodyParser) {
-      req.body = await parseBody(
-        req,
+      apiReq.body = await parseBody(
+        apiReq,
         config.api && config.api.bodyParser && config.api.bodyParser.sizeLimit
           ? config.api.bodyParser.sizeLimit
           : '1mb'
       )
     }
 
-    res.status = statusCode => sendStatusCode(res, statusCode)
-    res.send = data => sendData(res, data)
-    res.json = data => sendJson(res, data)
+    apiRes.status = statusCode => sendStatusCode(apiRes, statusCode)
+    apiRes.send = data => sendData(apiRes, data)
+    apiRes.json = data => sendJson(apiRes, data)
 
     const resolver = interopDefault(resolverModule)
     resolver(req, res)
   } catch (err) {
     if (err instanceof ApiError) {
-      sendError(res, err.statusCode, err.message)
+      sendError(apiRes, err.statusCode, err.message)
     } else {
       console.error(err)
       if (onError) await onError({ err })
-      sendError(res, 500, 'Internal Server Error')
+      sendError(apiRes, 500, 'Internal Server Error')
     }
   }
 }

packages/next/next-server/server/next-server.ts

@@ -76,7 +76,8 @@ export default class Server {
   pagesDir?: string
   publicDir: string
   hasStaticDir: boolean
-  pagesManifest: string
+  serverBuildDir: string
+  pagesManifest?: { [name: string]: string }
   buildId: string
   renderOpts: {
     poweredByHeader: boolean
@@ -114,13 +115,6 @@ export default class Server {
     this.distDir = join(this.dir, this.nextConfig.distDir)
     this.publicDir = join(this.dir, CLIENT_PUBLIC_FILES_PATH)
     this.hasStaticDir = fs.existsSync(join(this.dir, 'static'))
-    this.pagesManifest = join(
-      this.distDir,
-      this.nextConfig.target === 'server'
-        ? SERVER_DIRECTORY
-        : SERVERLESS_DIRECTORY,
-      PAGES_MANIFEST
-    )
 
     // Only serverRuntimeConfig needs the default
     // publicRuntimeConfig gets it's default in client/index.js
@@ -164,19 +158,26 @@ export default class Server {
       })
     }
 
+    this.serverBuildDir = join(
+      this.distDir,
+      this._isLikeServerless ? SERVERLESS_DIRECTORY : SERVER_DIRECTORY
+    )
+    const pagesManifestPath = join(this.serverBuildDir, PAGES_MANIFEST)
+
+    if (!dev) {
+      this.pagesManifest = require(pagesManifestPath)
+    }
+
     this.router = new Router(this.generateRoutes())
     this.setAssetPrefix(assetPrefix)
 
     // call init-server middleware, this is also handled
     // individually in serverless bundles when deployed
     if (!dev && this.nextConfig.experimental.plugins) {
-      const serverPath = join(
-        this.distDir,
-        this._isLikeServerless ? 'serverless' : 'server'
-      )
-      const initServer = require(join(serverPath, 'init-server.js')).default
+      const initServer = require(join(this.serverBuildDir, 'init-server.js'))
+        .default
       this.onErrorMiddleware = require(join(
-        serverPath,
+        this.serverBuildDir,
         'on-error-server.js'
       )).default
       initServer()
@@ -495,6 +496,24 @@ export default class Server {
     return routes
   }
 
+  private async getPagePath(pathname: string) {
+    return getPagePath(
+      pathname,
+      this.distDir,
+      this._isLikeServerless,
+      this.renderOpts.dev
+    )
+  }
+
+  protected async hasPage(pathname: string): Promise<boolean> {
+    let found = false
+    try {
+      found = !!(await this.getPagePath(pathname))
+    } catch (_) {}
+
+    return found
+  }
+
   protected async _beforeCatchAllRender(
     _req: IncomingMessage,
     _res: ServerResponse,
@@ -504,6 +523,9 @@ export default class Server {
     return false
   }
 
+  // Used to build API page in development
+  protected async ensureApiPage(pathname: string) {}
+
   /**
    * Resolves `API` request, in development builds on demand
    * @param req http request
@@ -511,77 +533,53 @@ export default class Server {
    * @param pathname path of request
    */
   private async handleApiRequest(
-    req: NextApiRequest,
-    res: NextApiResponse,
+    req: IncomingMessage,
+    res: ServerResponse,
     pathname: string
   ) {
+    let page = pathname
     let params: Params | boolean = false
-    let resolverFunction: any
-
-    try {
-      resolverFunction = await this.resolveApiRequest(pathname)
-    } catch (err) {}
+    let pageFound = await this.hasPage(page)
 
-    if (
-      this.dynamicRoutes &&
-      this.dynamicRoutes.length > 0 &&
-      !resolverFunction
-    ) {
+    if (!pageFound && this.dynamicRoutes) {
       for (const dynamicRoute of this.dynamicRoutes) {
         params = dynamicRoute.match(pathname)
         if (params) {
-          resolverFunction = await this.resolveApiRequest(dynamicRoute.page)
+          page = dynamicRoute.page
+          pageFound = true
           break
         }
       }
     }
 
-    if (!resolverFunction) {
+    if (!pageFound) {
       return this.render404(req, res)
     }
+    // Make sure the page is built before getting the path
+    // or else it won't be in the manifest yet
+    await this.ensureApiPage(page)
+
+    const builtPagePath = await this.getPagePath(page)
+    const pageModule = require(builtPagePath)
 
     if (!this.renderOpts.dev && this._isLikeServerless) {
-      const mod = require(resolverFunction)
-      if (typeof mod.default === 'function') {
-        return mod.default(req, res)
+      if (typeof pageModule.default === 'function') {
+        return pageModule.default(req, res)
       }
     }
 
-    await apiResolver(
-      req,
-      res,
-      params,
-      resolverFunction ? require(resolverFunction) : undefined,
-      this.onErrorMiddleware
-    )
-  }
-
-  /**
-   * Resolves path to resolver function
-   * @param pathname path of request
-   */
-  protected async resolveApiRequest(pathname: string): Promise<string | null> {
-    return getPagePath(
-      pathname,
-      this.distDir,
-      this._isLikeServerless,
-      this.renderOpts.dev
-    )
+    await apiResolver(req, res, params, pageModule, this.onErrorMiddleware)
   }
 
   protected generatePublicRoutes(): Route[] {
     const routes: Route[] = []
     const publicFiles = recursiveReadDirSync(this.publicDir)
-    const serverBuildPath = join(
-      this.distDir,
-      this._isLikeServerless ? SERVERLESS_DIRECTORY : SERVER_DIRECTORY
-    )
-    const pagesManifest = require(join(serverBuildPath, PAGES_MANIFEST))
 
     publicFiles.forEach(path => {
       const unixPath = path.replace(/\\/g, '/')
       // Only include public files that will not replace a page path
-      if (!pagesManifest[unixPath]) {
+      // this should not occur now that we check this during build
+      if (!this.pagesManifest![unixPath]) {
         routes.push({
           match: route(unixPath),
           type: 'route',
@@ -601,8 +599,9 @@ export default class Server {
   }
 
   protected getDynamicRoutes() {
-    const manifest = require(this.pagesManifest)
-    const dynamicRoutedPages = Object.keys(manifest).filter(isDynamicRoute)
+    const dynamicRoutedPages = Object.keys(this.pagesManifest!).filter(
+      isDynamicRoute
+    )
     return getSortedRoutes(dynamicRoutedPages).map(page => ({
       page,
       match: getRouteMatcher(getRouteRegex(page)),

packages/next/server/next-dev-server.ts

@@ -246,6 +246,15 @@ export default class DevServer extends Server {
     }
   }
 
+  protected async hasPage(pathname: string): Promise<boolean> {
+    const pageFile = await findPageFile(
+      this.pagesDir!,
+      normalizePagePath(pathname),
+      this.nextConfig.pageExtensions
+    )
+    return !!pageFile
+  }
+
   protected async _beforeCatchAllRender(
     req: IncomingMessage,
     res: ServerResponse,
@@ -257,13 +266,7 @@ export default class DevServer extends Server {
     // check for a public file, throwing error if there's a
     // conflicting page
     if (await this.hasPublicFile(pathname!)) {
-      const pageFile = await findPageFile(
-        this.pagesDir!,
-        normalizePagePath(pathname!),
-        this.nextConfig.pageExtensions
-      )
-
-      if (pageFile) {
+      if (await this.hasPage(pathname!)) {
         const err = new Error(
           `A conflicting public file and page file was found for path ${pathname} https://err.sh/zeit/next.js/conflicting-public-file-page`
         )
@@ -381,21 +384,8 @@ export default class DevServer extends Server {
     return !snippet.includes('data-amp-development-mode-only')
   }
 
-  /**
-   * Check if resolver function is build or request new build for this function
-   * @param {string} pathname
-   */
-  protected async resolveApiRequest(pathname: string): Promise<string | null> {
-    try {
-      await this.hotReloader!.ensurePage(pathname)
-    } catch (err) {
-      // API route dosn't exist => return 404
-      if (err.code === 'ENOENT') {
-        return null
-      }
-    }
-    const resolvedPath = await super.resolveApiRequest(pathname)
-    return resolvedPath
+  protected async ensureApiPage(pathname: string) {
+    return this.hotReloader!.ensurePage(pathname)
   }
 
   async renderToHTML(