The Subscribing and Unsubscribing section of the Observable Contract is definitive regarding your question. It states: When an Observable issues an OnError or OnComplete notification to its observers, this ends the subscription. Observers do not need to issue an Unsubscribe notification to end subscriptions that are ended by the Observable in this way. This is … Read more
The current “pipable” variant of this operator is called finalize() (since RxJS 6). The older and now deprecated “patch” operator was called finally() (until RxJS 5.5). I think finalize() operator is actually correct. You say: do that logic only when I subscribe, and after the stream has ended which is not a problem I think. … Read more
You certainly shouldn’t have your methods take in params that don’t concern them! To your main question: How to pass results between chained observables without the problems i’ve mentioned? Use a single scope (nested pipes) The code below is equivalent to your sample code, with no need to pass the unnecessary properties. The previously returned … Read more
You could try to use RxJS bufferCount and concatMap operators along with forkJoin(). From bufferCount docs: Collect emitted values until provided number is fulfilled, emit as array. So it collects n number of notifications and emit it as an array. We could then pass the array through forkJoin() for n number of parallel requests. Try … Read more
distinctUntilChanged when applied to the valueChanges observable… …is probably never going to work! It only works as expected on an individual value (as you said). So you’ll get a new value even if nothing has changed. To track changes for the whole form you need to write a custom comparer, the simplest of which uses … Read more
If the server sends a redirect with a 302 status code with the URL to redirect within a Location header, the redirect is automatically handled by the browser, i.e. a request to this URL is executed. That’s why XHR (and the Angular2 wrapper around it, i.e. the Http class) won’t see the result of the … Read more
Short answer, no this is not needed, but it also doesn’t hurt. Long answer: Unsubscribing / completing in angular is only needed when it prevents garbage collection because the subscription involves some subject that will outlive the component due to be collected. This is how a memory leak is created. if I have service: export … Read more
Operator chaining has been transitioned to the use of .pipe() in RXJS v6, you should follow the recommended migration path for RXJS. Additionally, the catch operator has been renamed to catchError. Here is how it should be done now: const request = this.evidenceService.get().pipe( map((res) => res.data)), catchError(error => Observable.of(null)) );
Here is what I ended up with, after realizing that a delay was a good solution in terms of UX because it allowed the loader to show only when the loading time is worth displaying a loader. I don’t like this solution because I prefer when the state is being encapsulated into Observable operators rather … Read more
The flatMap operator allows to do that. I don’t fully understand what you try to do but I’ll try to provide an answer… If you want load all the getPostsPerUser() { return this.http.get(“https://stackoverflow.com/users”) .map(res => res.json()) .flatMap((result : Array<User>) => { return Observable.forkJoin( result.map((user : User) => user.getPosts()); }); } Observable.forkJoin allows you to wait … Read more