rxjs6

问题 I have difficulties using the power of Observables i.e. RxJs 6 to correctly pipe, tap, map, mergemap or whatever my HttpClient requests. The version hell with all the different functions makes it not very easy... So what I need is to first make a REST call, then depending on the result probably do a second REST call and map the potentially two received data objects in one new data object. The function should return an Observable . So currently, I solved it with a subject that I am be able to

问题 I have difficulties using the power of Observables i.e. RxJs 6 to correctly pipe, tap, map, mergemap or whatever my HttpClient requests. The version hell with all the different functions makes it not very easy... So what I need is to first make a REST call, then depending on the result probably do a second REST call and map the potentially two received data objects in one new data object. The function should return an Observable . So currently, I solved it with a subject that I am be able to

问题 I wrote a function that is pipe -able: HandleHttpBasicError<T>() { return ((source:Observable<T>) => { return source.pipe( catchError((err:any) => { let msg = ''; if(err && err instanceof HttpErrorResponse) { if(err.status == 0) msg += "The server didn't respond"; } throw { err, msg } as CustomError }) ) }) } I can use this function this way in my HttpService : checkExist(id:string) { return this.http.head<void>(environment.apiUrl + 'some_url/' + id) .pipe( HandleHttpBasicError(), catchError(

问题 I wrote a function that is pipe -able: HandleHttpBasicError<T>() { return ((source:Observable<T>) => { return source.pipe( catchError((err:any) => { let msg = ''; if(err && err instanceof HttpErrorResponse) { if(err.status == 0) msg += "The server didn't respond"; } throw { err, msg } as CustomError }) ) }) } I can use this function this way in my HttpService : checkExist(id:string) { return this.http.head<void>(environment.apiUrl + 'some_url/' + id) .pipe( HandleHttpBasicError(), catchError(

问题 For learning purposes, I'm creating a Node app that will need to take x RxJS observables from an array and combine into a single stream of events. I want to know when events occur in any observable, in any order (not in any sequence or full completion). I feel it should be in a single merged stream of events. Basically, the first event that comes through from any observable will complete. For this, I felt merge() will do the trick. As merge doesn't take arrays directly as a parameter, I'm

问题 I do not understand from the docs. Could anyone explain it to me? 回答1: Most of the operators are working in streamed sequence, for example: source$.pipe( map((a: string) => changeAndReturnArray(a)), filter((b: string[]) => giveMeOnlySymbolsThatAreAfterNInAlphabet(b)), switchMap((c: string[]) => putToSomeObservable(c)) .... ); In that example you are not 'breaking' the stream, or jumping outside of it to do some external action. Jumping outside of stream is possible with 'tap' operator, where

问题 We recently upgraded to Angular 6.0.3, RxJs 6.2.0 and jest 23.1.0 (upgrading from RxJS 5 & Angular 4). There seems to be a problem with Jest & RxJs as failing expect-statements inside a subscribe-Block do not mark the test as failed. Here's a minimal example: it("should fail", () => { const obs = Observable.create((observer) => { observer.next(false); }); obs.subscribe((value) => { console.log(value); // => false expect(value).toBeTruthy(); }); }); The expect-Statement gets executed, but the

问题 I want to create an Observable of many observables (merge them). This could be achieved with merge(...arrayOfObservables) . The problem is that some time this array will be changed and the observable should subscribe to the new observables, too. 回答1: You can push new Observables to an array and then emit the array and subscribe to them with switchMap . import { of, merge, BehaviorSubject } from 'rxjs'; import { switchMap } from 'rxjs/operators'; const s = new BehaviorSubject([of(1), of(2), of

问题 I am working on an effect, that will be polling server. What I want to achieve is as follows: 1) Send GET request to server 2) After response is received, wait 3 seconds 3) Send same GET request 4) After response is received, wait 3 seconds 5) Send same GET request ... and so on. The code that I have now, doesn't quite work, as it polls server every 3 seconds, no matter if response was received or not: @Effect() pollEntries$ = this.actions$.pipe( ofType(SubnetBrowserPageActions

问题 source<http> .pipe( switchMap(d => this.http.get(d)) .pipe( switchMap(j => this.http.get(j)) ) ) .subscribe() Hello, I need to make 3 http requests consecutively where each call contains data for the next call.. are nested switch maps the best practice for this case? 回答1: You don't need to nest them. You can simply chain them: source<http> .pipe( switchMap(d => this.http.get(d)), switchMap(j => this.http.get(j)) ) .subscribe() Apart from that, using multiple switchMap is the way to go. 回答2: