角度5 HttpClient可观察的重用

Question

i create a service returning user details from server using the HttpClient.get.

public getUser(id: number): Observable<User>{

return this.http
  .get<User>('myUrl?id='+id);}

i have injected the service into a component. in the component i would like to get a user so i have subscribed to the service method wich is returning Observable.

so far so good.

my problam: now i would like to get another user and the question is how i activate the service method to get the user again ??

should i unsubscribe and subscribe again every time i need a user ?

Answer 1

All Observables returned from HttpClient are cold .

Observables are functions that tie an observer to a producer. An observable is “cold” if its underlying producer is created and activated during subscription. This means, that if observables are functions, then the producer is created and activated by calling that function. ( source )

so, it's fine to subscribe to your service HttpClient method multiple time and call it from different places, and you don't need to unsubscribe from it. But please keep it in mind it's neccesery to unsubscribe all your subscribers on component destroy.