CODEWITHSUNDEEP
angular
Rijo
Rijo

Reputation: 3043

Angular 4 pass service response values to multiple components

I need pass one http response values to multiple components.

my home component html is

<app-featured></app-featured>
<app-filter></app-filter>
<app-business></app-business>

service file data-video.service

getPosts() {
     return this.http.get('http://grace-controls.com/mind-grid/mind_select.php')
     .map(res=>res.json())
   }

featured.component.ts

featured component is a slick slider

ngOnInit() {
    this.dataServices.getPosts().subscribe((posts)=>{
          this.slides.splice(0, 1);
          for(let i=0; i<posts.length;i++) {
            this.slides.push({img:posts[i].image_url});
          }
        })
}
slides = [{img:''}];

business.component.ts

    ngOnInit() {
    //Here I have to request the same data service method or any common object access values here?
      }

How to get and print the values in business component?. Which is the most preferable way to do? I am beginner in Angular please help me?

Upvotes: 4

Views: 1439

Answers (3)

Yanis-git
Yanis-git

Reputation: 7885

i recommand you to create BehaviorSubject to manage locally your Posts collection.

first things is to create Model like this :

/**
 * Strong type each item of your posts api.
 */
export class PostModel {
  id: string;
  title: string;
  descreption: string;
  image_url: string;
  video_id: string;
  country: string;
  language: string;
  company: string;
  date: string;
  clap: string;
  views: string;
  username: string;
}

then you service can looks like this :

@Injectable()
export class PostService {
  // Should be private and expose by magic getter, present bellow.
  private _posts$ : BehaviorSubject<PostModel[]>; 

  constructor(private http: HttpClient) {
    // We init by empty array, this means if you subscribe before ajax answer, you will receive empty array, then be notify imediatly after request is process.
    this._posts$ = new BehaviorSubject([]);
    // Because this data is mandatory, we ask directly from constructor.
    this.loadPost();
  }

  private loadPost() {
    this
    .http
    .get('http://grace-controls.com/mind-grid/mind_select.php')
    .pipe(map(res => (res as PostModel[]))) // We strong type as PostModel array
    .subscribe(posts => this._posts$.next(posts)); // we push data on our internal Observable.
  }
  // Magic getter who return Observable of PostModel array.
  get posts$() : Observable<PostModel[]> {
    return this._posts$.asObservable();
  }
  // magic getter who return Observable of {img:string} array.
  get slides$(): Observable<Array<{img:string}>> {
    return this._posts$.pipe(map(posts => {
        return posts.map(post => {
          return {
            img: post.image_url
          }
        });
    }));
  }
}

Then you can consume your data everywhere on your application, just do :

export class AppComponent implements OnInit{

  constructor(private postService: PostService) { }

  ngOnInit() {
    this.postService.posts$.subscribe(posts => {
      console.log(posts);
    });
    // OR
    this.postService.slides$.subscribe(slides => {
      console.log(slides);
    });
  }
}

Detail : BehaviorSuject have to be init with default value, then when consumer subscribe to it, he will always return last emitted value.

Sample : Online sample Unfortunatly, ajax request throw error from your url because your server is not over https. Anyway this online sample is to have full code ready to check.

__ UPDATE __

I have update my sample, comment HttpCall and replace it by dummy data.

Upvotes: 3

Fateh Mohamed
Fateh Mohamed

Reputation: 21397

if you have a data to share to be accessible from all component, you can use ngrx store for state management if you look for the best and clean solution, you can do a call only once and store the result in the store 

 you can dispatch your result inside the service

getPosts() {
  return this.http.get('http://grace-controls.com/mind-grid/mind_select.php')
 .map(res=>res.json()).subscribe((results) => {
    this.store.dispatch(new yourActions.GetPosts(result));
 })
}

and you can get your posts list everywhere you need it by calling

this.store.select('postsList');

that return an observable, you can subscribe and get your data

Upvotes: 1

Sajeetharan
Sajeetharan

Reputation: 222657

You should go for the option of using Shared Service across the components. A service in Angular is a singleton, meaning it is managed as a single instance. So if each of the components access the service, they will access the same shared data.

Here is an Example.

Upvotes: 2

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