👀 Views: 62 💬 Answers: 1 📅 Created: 2025-06-21

angular rxjs httpclient forkjoin typescript

I'm attempting to set up I'm maintaining legacy code that Quick question that's been bugging me - I'm working on an Angular 14 application where I need to fetch user details along with their associated posts from two different APIs. The scenario arises when I try to manage the nested observables within my component. When I subscribe to the user observable and then, within that subscription, make another call to fetch posts, the data doesn't bind correctly and ends up returning `undefined` for the posts. Here is a simplified version of my code: ```typescript // user.service.ts import { Injectable } from '@angular/core'; import { HttpClient } from '@angular/common/http'; import { Observable } from 'rxjs'; @Injectable({ providedIn: 'root' }) export class UserService { constructor(private http: HttpClient) {} getUser(userId: number): Observable<User> { return this.http.get<User>(`/api/users/${userId}`); } getUserPosts(userId: number): Observable<Post[]> { return this.http.get<Post[]>(`/api/users/${userId}/posts`); } } ``` ```typescript // user.component.ts import { Component, OnInit } from '@angular/core'; import { UserService } from './user.service'; import { forkJoin } from 'rxjs'; @Component({ selector: 'app-user', templateUrl: './user.component.html' }) export class UserComponent implements OnInit { user: User; posts: Post[]; constructor(private userService: UserService) {} ngOnInit() { const userId = 1; // For testing this.userService.getUser(userId).subscribe(user => { this.user = user; this.userService.getUserPosts(userId).subscribe(posts => { this.posts = posts; // This is where it might return undefined }); }); } } ``` I've checked to ensure that both API endpoints are returning the expected data. The user data displays correctly, but the posts often return as `undefined`. I've also tried using `forkJoin` to handle both calls concurrently, but I keep running into issues with handling the results. Here's how I attempted using `forkJoin`: ```typescript ngOnInit() { const userId = 1; // For testing forkJoin({ user: this.userService.getUser(userId), posts: this.userService.getUserPosts(userId) }).subscribe(({ user, posts }) => { this.user = user; this.posts = posts; }); } ``` However, the `forkJoin` method results in an behavior stating that the HTTP request failed with a 404 status code when fetching posts. I’m not sure if I’m missing something in the API setup or if there's a better pattern for managing nested observables. Any guidance on how to properly handle these API calls and ensure both user and posts data are correctly assigned would be greatly appreciated. What am I doing wrong? This is part of a larger application I'm building. What's the best practice here? This is happening in both development and production on macOS. I'm working with Typescript in a Docker container on CentOS. What would be the recommended way to handle this?