Angular SSR - 无法读取未定义的属性（读取 'unsubscribe'）

Question

我只是为了 SEO 目的将我的 angular 网络应用程序转换为 ssr。我成功地纠正了主要问题，但最后一个我不知道如何处理。

我有一项服务 sqs.service.ts body

import { Injectable, OnInit } from '@angular/core';
import { CookieService } from 'ngx-cookie-service';
import { Router } from '@angular/router';
import {SNSClient, PublishCommand, MessageAttributeValue} from "@aws-sdk/client-sns";

import { interval, Subscription } from 'rxjs';
import { CognitoIdentityClient } from "@aws-sdk/client-cognito-identity";
import { fromCognitoIdentityPool }  from "@aws-sdk/credential-provider-cognito-identity";
import {environment} from "../../../../../../environments/environment";
import {AuthService} from "../../../../../modules/auth";


export interface SnsNotificationMessage {
  Message: string;
  TopicArn: string;
  MessageAttributes: { [key: string]: MessageAttributeValue; }
}

@Injectable({ providedIn: 'root' })
export class SqsService {

  // Set the AWS Region
  REGION = "eu-west-3";
  subscription: Subscription;
  // Set the parameters
  mnotificationTopicArn = environment.MNOTIFICATION_TOPIC_ARN;



  constructor(
    private cookieService: CookieService,
    private router: Router,
    private authentService: AuthService,
  ) {


  }




  ngOnDestroy() {
    this.subscription.unsubscribe();
  }


  /**
   * Send notification to mnotification
   * @param params
   */
  sendNotification(params: SnsNotificationMessage) {

    const idToken = this.cookieService.get(this.authentService.GARA_WEB_USER_JWT_ID_TOKEN_COOKIE);
    // create sns client
    const snsClient = new SNSClient({
      region: this.REGION,
      credentials: fromCognitoIdentityPool({
        client: new CognitoIdentityClient({region: this.REGION}),
        identityPoolId: environment.identityPoolId,
        logins: {
          [environment.cognitoPoolId]: idToken   // 'COGNITO_ID' has the format 'cognito-idp.REGION.amazonaws.com/COGNITO_USER_POOL_ID'
        },
      })
    });

    const run = async () => {
      try {
        const data = await snsClient.send(new PublishCommand(params));
        console.log("Success.",  data);
        return data; // For unit tests.
      } catch (err) {
        console.log("Error", err.stack);
      }
    };
    run();
  }

}

每次刷新我的应用程序页面时，我都会收到错误

TypeError: Cannot read properties of undefined (reading 'unsubscribe')
    at SqsService.ngOnDestroy (C:\Users\koste\OneDrive\Documents\Gara\front end\gara-web\dist\gara-app\server.js:49:23)
    at C:\Users\koste\OneDrive\Documents\Gara\front end\gara-web\dist\gara-app\server\main.js:58964:55
    at Set.forEach (<anonymous>)
    at R3Injector.destroy (C:\Users\koste\OneDrive\Documents\Gara\front end\gara-web\dist\gara-app\server\main.js:58964:28)
    at NgModuleRef.destroy (C:\Users\koste\OneDrive\Documents\Gara\front end\gara-web\dist\gara-app\server\main.js:73080:41)
    at C:\Users\koste\OneDrive\Documents\Gara\front end\gara-web\dist\gara-app\server\main.js:77106:56
    at Array.forEach (<anonymous>)
    at PlatformRef.destroy (C:\Users\koste\OneDrive\Documents\Gara\front end\gara-web\dist\gara-app\server\main.js:77106:31)
    at complete (C:\Users\koste\OneDrive\Documents\Gara\front end\gara-web\dist\gara-app\server\main.js:93213:26)
    at C:\Users\koste\OneDrive\Documents\Gara\front end\gara-web\dist\gara-app\server\main.js:93217:24

当我删除或评论下面的代码时，我可以成功地重新加载页面，

  ngOnDestroy() {
    //this.subscription.unsubscribe();
  }

但我在代码中遇到了这个新错误

ERROR NetworkError
    at XMLHttpRequest.send (C:\Users\koste\OneDrive\Documents\Gara\front end\gara-web\dist\gara-app\server\main.js:521132:19)
    at Observable._subscribe (C:\Users\koste\OneDrive\Documents\Gara\front end\gara-web\dist\gara-app\server\main.js:13619:17)
    at Observable._trySubscribe (C:\Users\koste\OneDrive\Documents\Gara\front end\gara-web\dist\gara-app\server\main.js:504773:25)
    at Observable.subscribe (C:\Users\koste\OneDrive\Documents\Gara\front end\gara-web\dist\gara-app\server\main.js:504759:22)
    at scheduleTask (C:\Users\koste\OneDrive\Documents\Gara\front end\gara-web\dist\gara-app\server\main.js:92458:32)
    at Observable._subscribe (C:\Users\koste\OneDrive\Documents\Gara\front end\gara-web\dist\gara-app\server\main.js:92496:13)
    at Observable._trySubscribe (C:\Users\koste\OneDrive\Documents\Gara\front end\gara-web\dist\gara-app\server\main.js:504773:25)
    at Observable.subscribe (C:\Users\koste\OneDrive\Documents\Gara\front end\gara-web\dist\gara-app\server\main.js:504759:22)
    at innerSubscribe (C:\Users\koste\OneDrive\Documents\Gara\front end\gara-web\dist\gara-app\server\main.js:505776:23)
    at MergeMapSubscriber._innerSub (C:\Users\koste\OneDrive\Documents\Gara\front end\gara-web\dist\gara-app\server\main.js:510200:98)

请问我该如何更正它？没有 ssr，它工作得很好。问题的原因是什么？提前致谢。

Answer 1

ngOnDestroy

在 Angular 销毁 directive/component 之前进行清理。取消订阅可观察对象并分离事件处理程序以避免内存泄漏。

在 Angular 销毁 directive/component 之前调用。

从你的代码中我无法判断什么是取消订阅，也许你正在全局取消订阅，如果有时在 SSR 中是这种情况，你也必须告诉 angular 它的平台浏览器，因为你可能正在取消订阅某些服务使用 localStorage 或 cookies 等。当你遇到这样的问题时，我也推荐使用它。

import { PLATFORM_ID } from "@angular/core";
import { isPlatformBrowser } from '@angular/common';

constructor(@Inject(PLATFORM_ID) private platformId: Object) { }


ngOnDestroy() {
  if (isPlatformBrowser(this.platformId)) {
    this.subscription.unsubscribe();
   }
  }

在某些其他情况下，如果您使用某些插件等，则必须在 server.ts 处声明它们，例如：

server.ts

function setBrowserGlobals(distFolder) {
  const template = readFileSync(join(distFolder, 'index.html')).toString();
  const domino = require('domino');
  const win = domino.createWindow(template);
  global['window'] = win;
 // custom plugin cookieconsent
  global['window']['cookieconsent'] = {
    initialise: function () {
      //
    }
  };
}

export function app(): express.Express {
 const server = express();
  const distFolder = join(process.cwd(), 'dist/browser');
  const indexHtml = existsSync(join(distFolder, 'index.original.html')) ? 'index.original.html' : 'index';
  setBrowserGlobals(distFolder);
...

}

Angular SSR - 无法读取未定义的属性（读取 'unsubscribe'）

Angular SSR - Cannot read properties of undefined (reading 'unsubscribe')

angular

typescript

server-side-rendering

angular11