What could be causing the lack of updates for my service on the app component?

Question

What could be causing the lack of updates for my service on the app component?

I am currently using Ionic 4 and facing an issue with displaying information about the logged-in user. The code works perfectly in all components except for the app component. I have a variable named userData which is a BehaviorSubject. Can someone help me identify what might be wrong with my code?

auth.service.ts

import { Platform } from '@ionic/angular';
import { Injectable } from '@angular/core';
import { Storage } from '@ionic/storage';
import { BehaviorSubject, Observable, from, of, throwError } from 'rxjs';
import { take, map,tap, switchMap, catchError } from 'rxjs/operators;
import { JwtHelperService } from "@auth0/angular-jwt";
import { HttpClient } from '@angular/common/http';
import { Router } from '@angular/router';
import { Tokens } from '../models/tokens';environment';
...

<p>app.component.ts (Utilizing the getUser() function to retrieve current user details)</p>

<pre><code>import { Component, OnInit, ViewChildren, QueryList, OnChanges } from '@angular/core';

import { Platform, ModalController, ActionSheetController, PopoverController, IonRouterOutlet, MenuController } from '@ionic/angular';
import { SplashScreen } from '@ionic-native/splash-screen/ngx';
import { StatusBar } from '@ionic-native/status-bar/ngx';
import { Router } from '@angular/router';
import { faHome, faInfo, faFileContract } from '@fortawesome/free-solid-svg-icons';
import { ToastController } from '@ionic/angular';
import { AuthService } from './auth/services/auth.service';
...

app.component.html (In this section, I aim to display user information, but it seems to not work specifically in this component)

<ion-app>
  <ion-split-pane contentId="main-content">
    <ion-menu contentId="main-content" type="overlay">
      <ion-content>
        <ion-list id="inbox-list">
          <ion-list-header>Menu</ion-list-header>
          <ion-note *ngIf="user">{{ user.email }} </ion-note>

          <ion-menu-toggle auto-hide="false" *ngFor="let p of appPages; let i = index">
            <ion-item (click)="selectedIndex = i" routerDirection="root" [routerLink]="[p.url]" lines="none" detail="false" [class.selected]="selectedIndex == i">
              <fa-icon (keyup)="onKeyFaIcon($event)" slot="start" [icon]="p.icon"></fa-icon>

              <ion-label>{{ p.title }}</ion-label>
            </ion-item>
          </ion-menu-toggle>
        </ion-list>

      </ion-content>
    </ion-menu>
    <ion-router-outlet id="main-content"></ion-router-outlet>
  </ion-split-pane>
</ion-app

angular typescript ionic-framework ionic4

Answer 1

Answer №1

It seems like the userData variable gets a new value assigned in the functions loadStoredTokens() and login(). The function login() is not being called anywhere, and the loadStoreTokens() function is mistakenly invoked synchronously. It deals with data asynchronously, so the data flow should also be asynchronous.

Service

export class AuthService {
  constructor(private storage: Storage, private http: HttpClient, private plt: Platform, private router: Router) { 
    this.loadStoredTokens().subscribe(
      accessToken => {
        let decoded = helper.decodeToken(accessToken); 
        this.userData.next(decoded);
      },
    );  
  }

  loadStoredTokens() {
    const result = new Subject<any>();
    let platformObs = from(this.plt.ready());

    this.user = platformObs.pipe(
      switchMap(() => {
        return from(this.storage.get(refreshToken));
      }),
      map(refreshToken => {
        if (refreshToken) {
          this.refresh = refreshToken;
        } else {
          this.refresh = null;
        }
      }),
      switchMap(() => {
        return from(this.storage.get(accessToken));
      }),
      map(accessToken => {
        if (accessToken) {
          this.access = accessToken;
          result.next(accessToken);
        } else {
          this.access = null;
          result.next(null);
        }
      })
    );

  return result.asObservable();
}

Also, if you are using the getValue() function of BehaviorSubject, there is no need for the multicast observable. You could simply skip the getValue() in the service and subscribe to it in the component.

Service

getUser() {
  return this.userData.asObservable();
}

Component

ngOnInit() {
  this.auth.getUser().subscribe(
    user => { this.user = user }
  );
}

Use the safe navigation operator ?. in the template to check if the user variable is defined before accessing its properties. Initially, the value is null as indicated by the default value of the BehaviorSubject.

<ion-note *ngIf="user">{{ user?.email }} </ion-note>

Alternatively, you can skip the subscription in the component controller and use the async pipe in the template.

Component

ngOnInit() {
  this.user = this.auth.getUser();
}

Template

<ion-note *ngIf="user">{{ (user | async)?.email }} </ion-note>

Answer 2

It seems like the userData variable gets a new value assigned in the functions loadStoredTokens() and login(). The function login() is not being called anywhere, and the loadStoreTokens() function is mistakenly invoked synchronously. It deals with data asynchronously, so the data flow should also be asynchronous.

Service

export class AuthService {
  constructor(private storage: Storage, private http: HttpClient, private plt: Platform, private router: Router) { 
    this.loadStoredTokens().subscribe(
      accessToken => {
        let decoded = helper.decodeToken(accessToken); 
        this.userData.next(decoded);
      },
    );  
  }

  loadStoredTokens() {
    const result = new Subject<any>();
    let platformObs = from(this.plt.ready());

    this.user = platformObs.pipe(
      switchMap(() => {
        return from(this.storage.get(refreshToken));
      }),
      map(refreshToken => {
        if (refreshToken) {
          this.refresh = refreshToken;
        } else {
          this.refresh = null;
        }
      }),
      switchMap(() => {
        return from(this.storage.get(accessToken));
      }),
      map(accessToken => {
        if (accessToken) {
          this.access = accessToken;
          result.next(accessToken);
        } else {
          this.access = null;
          result.next(null);
        }
      })
    );

  return result.asObservable();
}

Also, if you are using the getValue() function of BehaviorSubject, there is no need for the multicast observable. You could simply skip the getValue() in the service and subscribe to it in the component.

Service

getUser() {
  return this.userData.asObservable();
}

Component

ngOnInit() {
  this.auth.getUser().subscribe(
    user => { this.user = user }
  );
}

Use the safe navigation operator ?. in the template to check if the user variable is defined before accessing its properties. Initially, the value is null as indicated by the default value of the BehaviorSubject.

<ion-note *ngIf="user">{{ user?.email }} </ion-note>

Alternatively, you can skip the subscription in the component controller and use the async pipe in the template.

Component

ngOnInit() {
  this.user = this.auth.getUser();
}

Template

<ion-note *ngIf="user">{{ (user | async)?.email }} </ion-note>

Answer 3

Answer №2

It is important to note that the BehaviorSubject operates asynchronously, requiring subscription to access its values.

In the ngOnInit lifecycle hook, ensure to subscribe to getUser() method to assign the user data to this.user property.

Remember that the data retrieval process is not immediate, so any dependencies on this.user should also be handled asynchronously.

For instance, in the template, you can validate with:

<ng-container *ngIf="user">
  {{ user }} - now ready for use
</ng-container>

Answer 4

It is important to note that the BehaviorSubject operates asynchronously, requiring subscription to access its values.

In the ngOnInit lifecycle hook, ensure to subscribe to getUser() method to assign the user data to this.user property.

Remember that the data retrieval process is not immediate, so any dependencies on this.user should also be handled asynchronously.

For instance, in the template, you can validate with:

<ng-container *ngIf="user">
  {{ user }} - now ready for use
</ng-container>

Answer 5

Answer №3

To ensure data is loaded correctly for the user during app initialization, it is recommended to utilize the async pipe. The code snippet provided below can guide you on how to implement this in your application.

app.component.html

<ion-app>
<ion-split-pane contentId="main-content">
<ion-menu contentId="main-content" type="overlay">
  <ion-content>
    <ion-list id="inbox-list">
      <ion-list-header>Menu</ion-list-header>
      <ion-note *ngIf="user">{{ auth?.userData?.email | async }} </ion-note>
    </ion-list>
  </ion-content>
</ion-menu>
<ion-router-outlet id="main-content"></ion-router-outlet>

Remember to store the email properties in the userData object and ensure that the AuthService scope is set as public when injecting it into the app.component.ts constructor.

Answer 6

To ensure data is loaded correctly for the user during app initialization, it is recommended to utilize the async pipe. The code snippet provided below can guide you on how to implement this in your application.

app.component.html

<ion-app>
<ion-split-pane contentId="main-content">
<ion-menu contentId="main-content" type="overlay">
  <ion-content>
    <ion-list id="inbox-list">
      <ion-list-header>Menu</ion-list-header>
      <ion-note *ngIf="user">{{ auth?.userData?.email | async }} </ion-note>
    </ion-list>
  </ion-content>
</ion-menu>
<ion-router-outlet id="main-content"></ion-router-outlet>

Remember to store the email properties in the userData object and ensure that the AuthService scope is set as public when injecting it into the app.component.ts constructor.

What could be causing the lack of updates for my service on the app component?

Answer №1

Answer №2

Answer №3

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