How to keep observable alive after error in RxJS 6 and Angular 6

问题

Can anyone help with the scenario where this._getReactions$.next() not working whenever this.http.get(...) gets an error. I want to keep observable alive to take the next input.

private _getReactions$: Subject<any> = new Subject();

 constructor() {
  this._getReactions$
  .pipe(
    switchMap(() => {
        return this.http.get(...)
        // http request 
    }),
    catchError(error => {
      console.log(error);
      return empty();
    })
  )
  .subscribe(data => {
      console.log(data)
      //results handling
  });
 }

onClick() {
  this._getReactions$.next();
}

回答1:

If observable dies it calls it error handler and they are closed you can't send anything through them that means they are closed everything upstream from that including the interval is dead.

what if we want to live.

sheilding the main observer chain is the solution
put catch inside of switchmap whenever a request is fired switchmap creates the ajax observable and this time with the catch.
switchmap has a behavior that it says my source is not completed yet so I don't really care if the child completes I gonna keep going.

     constructor() {
          this._getReactions$
          .pipe( tap(value=>{this.loading=true; return value}),
            switchMap(() => {
                return this.http.get(...).pipe(
       catchError((error)=>this.handleError(error)))
                // http request 
            }),
          )
          .subscribe(data => {
              console.log(data)
              //results handling
            this.error=false;
           this.loading=false
          });
         }

      private handleError(error: HttpErrorResponse) {

    this.error = true;
    console.log(error)
    this.loading = false
    return empty();
  }

Live Demo

Detailed Info

来源：https://stackoverflow.com/questions/52370506/how-to-keep-observable-alive-after-error-in-rxjs-6-and-angular-6