observable - w3toppers.com

How to create an RXjs RetryWhen with delay and limit on tries

You need to apply the limit to the retry signal, for instance if you only wanted 10 retries: loadSomething(): Observable<SomeInterface> { return this.http.get(this.someEndpoint, commonHttpHeaders()) .retryWhen(errors => // Time shift the retry errors.delay(500) // Only take 10 items .take(10) // Throw an exception to signal that the error needs to be propagated .concat(Rx.Observable.throw(new Error(‘Retry limit exceeded!’)) … Read more

Angular 2 cache observable http result data [duplicate]

If you lean into observables as a means of sharing data, you can adopt the following approach: import { Injectable } from ‘@angular/core’; import { HttpClient } from ‘@angular/common/http’; import { Observable, ReplaySubject } from ‘rxjs’; import { SomeModel } from ‘path/to/it’; @Injectable({ providedIn: ‘root’ }) export class CachedService { private dataSubject = new ReplaySubject<SomeModel>(1); … Read more

async/await in Angular `ngOnInit`

It is no different than what you had before. ngOnInit will return a Promise and the caller will ignore that promise. This means that the caller will not wait for everything in your method to finish before it proceeds. In this specific case it means the view will finish being configured and the view may … Read more

Difference between .unsubscribe to .take(1)

Each serves a different purpose so it’s hard to compare them. In general if you take this source: const source = range(1,3); … and consume it with subscribe() followed immediately by unsubscribe(): source.subscribe( console.log, undefined, () => console.log(‘complete’) ).unsubscribe(); … then all values from source are going to be emitted even though we called unsubscribe() … Read more

Wait for Angular 2 to load/resolve model before rendering view/template

Try {{model?.person.name}} this should wait for model to not be undefined and then render. Angular 2 refers to this ?. syntax as the Elvis operator. Reference to it in the documentation is hard to find so here is a copy of it in case they change/move it: The Elvis Operator ( ?. ) and null … Read more

Promise.all behavior with RxJS Observables?

The more straightforward alternative for emulating Promise.all is to use the forkJoin operator (it starts all observables in parallel and join their last elements): documentation related link: Cf. RxJS: concat three promises, distinguish results A bit out of scope, but in case it helps, on the subject of chaining promises, you can use a simple … Read more

Angular 6 View is not updated after changing a variable within subscribe

As far as I know, Angular is only updating the view, if you change data in the “Angular zone”. The asynchronous call in your example does not qualify for this. But if you want, you can put it in the Angular zone or use rxjs or extract part of the code to a new component … Read more

LiveData update on object field change

I don’t think there is any best practice as such recommended by android for this. I would suggest you to use the approach which uses cleaner & less boilerplate code. If you are using android data binding along with LiveData you can go with the following approach: Your POJO object would look something like this … Read more

Why is java.util.Observable not an abstract class?

Quite simply it’s a mistake that Observable is a class at all, abstract or otherwise. Observable should have been an interface and the JDK should have provided a convenient implementation (much like List is an interface and ArrayList is an implementation) There are quite a few “mistakes” in java, including: java.util.Stack is a class, not … Read more

Angular 2: Convert Observable to Promise

rxjs7 lastValueFrom(of(‘foo’)); https://indepth.dev/posts/1287/rxjs-heads-up-topromise-is-being-deprecated rxjs6 https://github.com/ReactiveX/rxjs/issues/2868#issuecomment-360633707 Don’t pipe. It’s on the Observable object by default. Observable.of(‘foo’).toPromise(); // this rxjs5 import ‘rxjs/add/operator/toPromise’; import ‘rxjs/add/operator/map’; … this._APIService.getAssetTypes() .map(assettypes => { this._LocalStorageService.setAssetTypes(assettypes); }) .toPromise() .catch(err => { this._LogService.error(JSON.stringify(err)); });