Backend communication functions seamlessly within the service scope, yet encounters obstacles beyond the service boundaries

Question

Backend communication functions seamlessly within the service scope, yet encounters obstacles beyond the service boundaries

I'm facing an issue with accessing data from my backend. Although the service successfully retrieves and logs the data, when I try to use that service in a different module, it either shows "undefined" or "Observable". Does anyone have any suggestions on how to resolve this? I've done some research on observables, but I'm still not completely clear on their functionality or if they are necessary in this case. Previously, I encountered problems with page elements loading before being directed properly, resulting in errors.

Here's the code for the backend call within my service, which correctly logs the game data:

  async getAllGames() {
      this.http.get(this.url).subscribe(gameData => {
        console.log(gameData);
        return gameData;
      });
    }

However, when I invoke this service function from another module, it returns "undefined".

async getGames() {
    const game = await this.games.getAllGames()
    console.log(game);
    _.each(game, (gameData) => {
      this.gamesArray.push(gameData);
    });

    // this.loadCharts(this.gamesArray);

  }

javascript angular typescript observable

Answer 1

Answer №1

Instead of using the subscribe function within a service, it is recommended to simply return an Observable object from the service. This way, you can easily subscribe to it in any component where it is needed.

To implement this change, modify your service code as shown below:

getAllGames(): Observable<any> {
    return this.http.get(this.url);
}

After making this change, you can then subscribe to the returned Observable in any of your components using the following syntax:

this.games.getAllGames()
    .subscribe((res: any) => {
        // TODO: Remove what you need with the response data
});

PS

If for any reason you still need to subscribe within the service itself, you should use a Promise instead. To do this, update your code as follows:

getAllGames(): Promise<any> {
    return new Promise((resolve, reject) => {
        this.http.get(this.url).subscribe((res: any) => {
            resolve(res);
        }, (err: any) => {
            reject(err);
        });
   });
}

From any of your components, you can then call the above Promise using the following syntax:

this.games.getAllGames()
    .then(data => {
        console.log(data);
    })
    .catch(err => console.error(err));

StackBlitz

Answer 2

Instead of using the subscribe function within a service, it is recommended to simply return an Observable object from the service. This way, you can easily subscribe to it in any component where it is needed.

To implement this change, modify your service code as shown below:

getAllGames(): Observable<any> {
    return this.http.get(this.url);
}

After making this change, you can then subscribe to the returned Observable in any of your components using the following syntax:

this.games.getAllGames()
    .subscribe((res: any) => {
        // TODO: Remove what you need with the response data
});

PS

If for any reason you still need to subscribe within the service itself, you should use a Promise instead. To do this, update your code as follows:

getAllGames(): Promise<any> {
    return new Promise((resolve, reject) => {
        this.http.get(this.url).subscribe((res: any) => {
            resolve(res);
        }, (err: any) => {
            reject(err);
        });
   });
}

From any of your components, you can then call the above Promise using the following syntax:

this.games.getAllGames()
    .then(data => {
        console.log(data);
    })
    .catch(err => console.error(err));

StackBlitz

Answer 3

Answer №2

I propose a unique solution that allows you to retrieve data efficiently across multiple components using a shared service:

Shared service:

class DataService { 
    private apiUrl: '...'
    public getGames$;

    constructor(private http: HttpClient) {
        this.getGames$ = this.http.get(this.apiUrl);
    } 
}

Component:

private gamesData;

constructor(private dataService: DataService) {
    this.dataService.getGames$.subscribe(gamesData => {
       this.gamesData = gamesData;
    });
}

Answer 4

I propose a unique solution that allows you to retrieve data efficiently across multiple components using a shared service:

Shared service:

class DataService { 
    private apiUrl: '...'
    public getGames$;

    constructor(private http: HttpClient) {
        this.getGames$ = this.http.get(this.apiUrl);
    } 
}

Component:

private gamesData;

constructor(private dataService: DataService) {
    this.dataService.getGames$.subscribe(gamesData => {
       this.gamesData = gamesData;
    });
}

Backend communication functions seamlessly within the service scope, yet encounters obstacles beyond the service boundaries

Answer №1

Answer №2

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