feat(platform-server): support document reference in render functions (#47032)

This commit updates the `renderModule` and `renderApplication` functions to also accept a document reference (in addition to the serialized document contents as a string). This should provide the necessary flexibility to NgUniversal (and other API consumers) to structure the logic to avoid serializing and parsing document multiple times during the SSR request.

PR Close #47032

packages/platform-server/src/server.ts

@@ -81,9 +81,14 @@ export class ServerModule {
 }
 
 function _document(injector: Injector) {
-  let config: PlatformConfig|null = injector.get(INITIAL_CONFIG, null);
-  const document = config && config.document ? parseDocument(config.document, config.url) :
-                                               getDOM().createHtmlDocument();
+  const config: PlatformConfig|null = injector.get(INITIAL_CONFIG, null);
+  let document: Document;
+  if (config && config.document) {
+    document = typeof config.document === 'string' ? parseDocument(config.document, config.url) :
+                                                     config.document;
+  } else {
+    document = getDOM().createHtmlDocument();
+  }
   // Tell ivy about the global document
   ɵsetDocument(document);
   return document;

packages/platform-server/src/utils.ts

@@ -16,7 +16,7 @@ import {BEFORE_APP_SERIALIZED, INITIAL_CONFIG} from './tokens';
 import {TRANSFER_STATE_SERIALIZATION_PROVIDERS} from './transfer_state';
 
 interface PlatformOptions {
-  document?: string;
+  document?: string|Document;
   url?: string;
   platformProviders?: Provider[];
 }
@@ -95,14 +95,16 @@ the server-rendered app can be properly bootstrapped into a client app.`);
 /**
  * Renders a Module to string.
  *
- * `document` is the full document HTML of the page to render, as a string.
+ * `document` is the document of the page to render, either as an HTML string or
+ *  as a reference to the `document` instance.
  * `url` is the URL for the current render request.
  * `extraProviders` are the platform level providers for the current render request.
  *
  * @publicApi
  */
 export function renderModule<T>(
-    module: Type<T>, options: {document?: string, url?: string, extraProviders?: StaticProvider[]}):
+    module: Type<T>,
+    options: {document?: string|Document, url?: string, extraProviders?: StaticProvider[]}):
     Promise<string> {
   const {document, url, extraProviders: platformProviders} = options;
   const platform = _getPlatform(platformDynamicServer, {document, url, platformProviders});
@@ -130,7 +132,8 @@ export function renderModule<T>(
  *  - `appId` - a string identifier of this application. The appId is used to prefix all
  *              server-generated stylings and state keys of the application in TransferState
  *              use-cases.
- *  - `document` - the full document HTML of the page to render, as a string.
+ *  - `document` - the document of the page to render, either as an HTML string or
+ *                 as a reference to the `document` instance.
  *  - `url` - the URL for the current render request.
  *  - `providers` - set of application level providers for the current render request.
  *  - `platformProviders` - the platform level providers for the current render request.
@@ -141,7 +144,7 @@ export function renderModule<T>(
  */
 export function renderApplication<T>(rootComponent: Type<T>, options: {
   appId: string,
-  document?: string,
+  document?: string|Document,
   url?: string,
   providers?: Array<Provider|ImportedNgModuleProviders>,
   platformProviders?: Provider[],

packages/platform-server/test/integration_spec.ts

@@ -11,7 +11,7 @@ import {DOCUMENT, isPlatformServer, PlatformLocation, ɵgetDOM as getDOM} from '
 import {HTTP_INTERCEPTORS, HttpClient, HttpClientModule, HttpEvent, HttpHandler, HttpInterceptor, HttpRequest} from '@angular/common/http';
 import {HttpClientTestingModule, HttpTestingController} from '@angular/common/http/testing';
 import {ApplicationRef, CompilerFactory, Component, destroyPlatform, getPlatform, HostBinding, HostListener, importProvidersFrom, Inject, Injectable, Input, NgModule, NgZone, OnInit, PLATFORM_ID, PlatformRef, Type, ViewEncapsulation} from '@angular/core';
-import {inject, waitForAsync} from '@angular/core/testing';
+import {inject, TestBed, waitForAsync} from '@angular/core/testing';
 import {BrowserModule, makeStateKey, Title, TransferState} from '@angular/platform-browser';
 import {BEFORE_APP_SERIALIZED, INITIAL_CONFIG, platformDynamicServer, PlatformState, renderModule, renderModuleFactory, ServerModule, ServerTransferStateModule} from '@angular/platform-server';
 import {Observable} from 'rxjs';
@@ -750,6 +750,38 @@ describe('platform-server integration', () => {
            });
          }));
 
+      it(`using ${isStandalone ? 'renderApplication' : 'renderModule'} ` +
+             `should allow passing a document reference`,
+         waitForAsync(() => {
+           const document = TestBed.inject(DOCUMENT);
+
+           // Append root element based on the app selector.
+           const rootEl = document.createElement('app');
+           document.body.appendChild(rootEl);
+
+           // Append a special marker to verify that we use a correct instance
+           // of the document for rendering.
+           const markerEl = document.createComment('test marker');
+           document.body.appendChild(markerEl);
+
+           const options = {document};
+           const bootstrap = isStandalone ?
+               renderApplication(MyAsyncServerAppStandalone, {document, appId: 'simple-cmp'}) :
+               renderModule(AsyncServerModule, options);
+           bootstrap
+               .then(output => {
+                 expect(output).toBe(
+                     '<html><head><title>fakeTitle</title></head>' +
+                     '<body><app ng-version="0.0.0-PLACEHOLDER">Works!<h1 textcontent="fine">fine</h1></app>' +
+                     '<!--test marker--></body></html>');
+                 called = true;
+               })
+               .finally(() => {
+                 rootEl.remove();
+                 markerEl.remove();
+               });
+         }));
+
       it('works with SVG elements', waitForAsync(() => {
            const options = {document: doc};
            const bootstrap = isStandalone ?