👀 Views: 6449 💬 Answers: 1 📅 Created: 2025-06-12

angular observables async-pipe typescript

I'm performance testing and I'm experiencing an issue in my Angular 15 application where data retrieved via an Observable isn't triggering change detection when used with the async pipe in my template..... I have a service that fetches data from an API and returns it as an Observable. In my component, I subscribe to this Observable and assign the result to a variable, but when I use the async pipe in my template, the UI doesn't update as expected. Here’s a snippet of my service that fetches user data: ```typescript import { Injectable } from '@angular/core'; import { HttpClient } from '@angular/common/http'; import { Observable } from 'rxjs'; @Injectable({ providedIn: 'root' }) export class UserService { private apiUrl = 'https://api.example.com/users'; constructor(private http: HttpClient) {} getUsers(): Observable<User[]> { return this.http.get<User[]>(this.apiUrl); } } ``` In my component, I have the following code: ```typescript import { Component, OnInit } from '@angular/core'; import { UserService } from './user.service'; import { Observable } from 'rxjs'; @Component({ selector: 'app-user-list', templateUrl: './user-list.component.html', }) export class UserListComponent implements OnInit { users$: Observable<User[]>; constructor(private userService: UserService) {} ngOnInit() { this.users$ = this.userService.getUsers(); } } ``` In my HTML template, I’m using the async pipe: ```html <ul> <li *ngFor="let user of users$ | async"> {{ user.name }} </li> </ul> ``` Despite the API call being successful and returning data, the list of users doesn’t render. I’ve checked the console for errors, and there's nothing thrown. I even tried wrapping the async pipe in a trackBy function to optimize rendering: ```html <li *ngFor="let user of users$ | async; trackBy: trackById"> ``` But still, no luck. I suspect it might be related to change detection strategy or some lifecycle issue, but I'm not sure how to address it. I’ve also confirmed that the API returns the correct data format. Any insights or solutions would be greatly appreciated! This is part of a larger API I'm building. What's the best practice here? I'm developing on Windows 11 with Typescript. What's the best practice here?