Angular get Http get one instance from observable

Question

I have a problem few of my components need same data from backend. So they all calls getDataMethod(); it looks like this

public getData(): Observable<any> {
  return this.http.get<any>(this.backendUrl);
}

response come in 5 seconds during this time I approximately call this method 3-4 times. So my question is were any they to return same observable to multiple subscribers?

score 1 · Accepted Answer · answered Dec 20 '17 at 13:55

1

You could publish the response as a replaySubject like so

public getData(): Observable<any> {
  return this.http.get<any>(this.backendUrl)
                .publishReplay(1)
                .refCount();
}

this will replay the results from the server without making a call to your api endpoint each time someone subscribes to the observable.

answered Dec 20 '17 at 13:55

JoshSommer

2,550
18
23

`shareReplay(1)` is shorter. – Ingo Bürk Dec 20 '17 at 20:54

score -1 · Answer 2 · answered Dec 20 '17 at 20:46

-1

you can use a "cache" variable.

data:any
public getData(): Observable<any> {
  if (this.data)
     return Observable.of(this.data);
  else
     return this.http.get<any>(this.backendUrl).do((data:any)=>
       {
           this.data=data
       });
}

answered Dec 20 '17 at 20:46

Eliseo

50,109
4
29
67

This will still cause multiple requests if you subscribe while the request hasn't finished. – Ingo Bürk Dec 20 '17 at 20:53

Angular get Http get one instance from observable

2 Answers2