CODEWITHSUNDEEP
angular
Zollia
Zollia

Reputation: 11

Service calling another service

I am trying to build a Service A using another Service B (https://angular.io/tutorial/toh-pt4) as following:

export class ServiceA {       
   private testMap: Map<string, string> = new Map();

   constructor(private serviceB: ServiceB) {}

   getTestMap(): Observable<Map<string, string>> {
      this.serviceB.getSomething(new HttpParams()).(data => {
         this.testMap.set('A', data);
      }
   }
}

and a component calls the map defined above as:

ngOnInit(){
   this.getTestMap();
}

getTestMap(): void {
   this.serviceA.getTestMap().subscribe(data => this.componentMap = data);

}

The data I got in the component is undefined. Thanks in advance.

Upvotes: 1

Views: 75

Answers (2)

Raj singh
Raj singh

Reputation: 391

I beleive the getTestMap method should be like:

getTestMap(): Observable<Map<string, string>> {
      return this.serviceB.getSomething(new HttpParams()).(data => {
         this.testMap.set('A', data);
    return data;
      }
   }

Upvotes: 0

Paweł Jacewicz
Paweł Jacewicz

Reputation: 144

getTestMap() from ServiceA should return an Observable. In your example you don't return anything. It could look like that (provided this.serviceB.getSomething() also returns an Observable):

export class ServiceA {       
   private testMap: Map<string, string> = new Map();

   constructor(private serviceB: ServiceB) {}

   getTestMap(): Observable<Map<string, string>> {
      return this.serviceB.getSomething(new HttpParams())
        .pipe(
          tap(data => this.testMap.set('A', data)),
          map(() => this.testMap)
        );
   }
}

And in your component:

ngOnInit(){
   this.getTestMap();
}

getTestMap(): void {
   this.serviceA.getTestMap().subscribe(data => this.componentMap = data);
}

Some useful resources:

Upvotes: 2

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