The correct way to subscribe to an Observable within Angular:

My goal is to create a valid observable by making a GET request and subscribing to it. This way, I can utilize the retrieved data in multiple components within my application.

The expected JSON structure from the server should look similar to this:

{
  "one": {
    "some": "variable",
    "more": "variables"
  },
  "two": {    
    "a": "variable",
    "b": "variable"
  },
  "three": {
    "things": [
      {        
        "some": "variable",
        "more": "variables
      },
      {
        "some": "variable",
        "more": "variables"
      }
    ],
    "peoples": [
      {
        "again": "variables",
        "women": {
          "next": "variable"
        },
        "man": {
          "last": "variable"
        }
      }
    ]
  }
}

Current approach: Referring to the Angular Documentation on Requesting a typed response, I have defined some data interfaces in the typescript file of a service named api.service:

export interface Response {
    one: One;
    two: Two;
    three: Three;
}

export interface One {
    some: string;
    more: string;
}

export interface Two {
    a: string;
    b: string;
}

export interface Three {
    things: Thing[];
    peoples: People[];
}

export interface Thing {
    some: string;
    more: string;
}

export interface People {
    again: string;
    women: Women;
    men: Men;
}

export interface Women {
    next: string;
}

export interface Men {
    last: string;
}

I have also implemented a function that makes a request to a specified URL within the service:

export class ApiService {
  private url = 'https://example.com/api/1234';

  constructor(private http: HttpClient) { }

  getApiResponse() {
    // Returns an Observable of type Response
    return this
      .http
      .get<Response>(this.url)
  }

Now comes the crucial question: Is this approach correct? And if so, how can I properly subscribe to the Observable returned by getApiResponse() in order to access, for example, the variable next within the Women interface?

Answer №1

Absolutely, this serves as the fundamental configuration for what you're inquiring about. Therefore, based on your existing setup, you have the option to subscribe to it either within your template HTML or your TS:

...
public information: Observable<any[]>; // (substitute any with the appropriate type)
this.information = this.getResponseData();
...

Application:

this.information.subscribe( info => console.log(info));

Alternatively, you can use the async pipe in your HTML file

<div *ngFor="let info of information | async">{{info}}</div>

Answer №2

Ah yes, as pointed out by @mwilson, that is the fundamental setup.

If you happen to be working in response.component.ts, here are the steps you can follow to subscribe to the observable:

import {ClassApiService} from './class-api.service.ts';

data: Observable<Response[]>;

// constructor
constructor (private apiService: ClassApiService) {}

ngOnInit(): void {
 this.apiService.getApiResponse().subscribe(
   (results: Response[]) => this.data = results;
 );
}

Next, in your HTML file like response.component.html -

<div *ngIf="data">
  <ul *ngFor="let d of data">
    <li>{{ d.someName }}</li>
  </ul>
</div>

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