rxjs

问题 How to make parallel calls HTTP get or post calls in angular 2? I have 2 service calls on the response of one callus have to make another call. Could some suggest me how to call make these parallel calls with error handling scenarios? 回答1: If your service is Observable based instead of Promise you can do forkJoin . It runs all observable sequences in parallel. For RxJS version < 6 import 'rxjs/add/observable/forkJoin'; Make sure to import forkJoin from rxjs library Observable.forkJoin

问题 I am currently building an Angular application where I make a request to an api, and I map the repsonse to two different arrays. I can use this data in my app.components.ts but I will make new components for what I need. How can I share the data between components to ensure that the components always have the latest data because I will also need to periodically call the API. I've seen some answers on SO and some youtube videos but I'm just not fully understanding it. The code of my service is

问题 Prior to getting the current customer orders I need to return his name, so my related Service class part looks like the following: Updated: export class AuthService { customerNameUrl = 'customers/name/' + name; . . . getCustomerOrders(customerName: string): Observable<CustomerOrder[]> { let currentCustomerName = this.getCurrentCustomer(customerName).subscribe(customer => customer.name); console.log(currentCustomerName); <--- Error let customerOrders = this.http.get<CustomerOrder[]>(this

问题 I have a simple login form component ( LoginComponent ) that calls the submitLogin method. import { Component, OnInit } from '@angular/core'; import { FormControl } from '@angular/forms'; import { Router, ActivatedRoute } from '@angular/router'; import { first } from 'rxjs/operators'; import { AuthenticationService } from '../../services'; @Component({ selector: 'login', templateUrl: './login.component.html', styleUrls: ['./login.component.scss'] }) export class LoginComponent implements

问题 In TypeScript / Angular, you would usually call a function that returns an observable and subscribe to it in a component like this: this.productsService.getProduct().subscribe((product) => { this.product = product }); This is fine when the code runs in a class that manages data, but in my opinion this should not be handled in the component. I may be wrong but i think the job of a component should be to ask for and display data without handling how the it is retrieved. In the angular template

问题 I have a hard time to grasp the way http Observables work. Http get always completes, when only one value arrives but there is no way to look up the implementation. Do they always complete after error or a value arrives? I have a lot of discussion with my collegues, because the use in every http operation the following procedure: const sub = this.http.get( enviroment.baseUrl + '/users').pipe(take(1)) .subscribe( value => { //do something with the value }, error => consol.log(error.message));

问题 I have learned of two different ways of making an Observable. First one was with a Subject, like so: // file A const message$ = new Subject(); // file B message$.subscribe( (message) => console.log(message) ); // file C message$.next("Hello there!"); This method of creating an Observable allows me to have a way to exchange data from file B to file C. The second way is via the Observable class, like so: // file A const click$ = new Observable( function(observer) { //Alternatively, I can use

问题 I am using a polling scheme in my Angular application using NgRx. To simplify things, I have something like the following... public stopPolling$ = createEffect(() => this.actions$.pipe( ofType(actions.stopPolling), tap(_ => this.isPollingActive = false), map(_ => actions.stopPolling()) ), { dispatch: false }); public continuePolling$ = createEffect(() => this.actions$.pipe( ofType(actions.getData), tap(_ => this.logger.debug('continue polling')), delay(8000), switchMap(_ => this.pollData()) )

问题 I am using a polling scheme in my Angular application using NgRx. To simplify things, I have something like the following... public stopPolling$ = createEffect(() => this.actions$.pipe( ofType(actions.stopPolling), tap(_ => this.isPollingActive = false), map(_ => actions.stopPolling()) ), { dispatch: false }); public continuePolling$ = createEffect(() => this.actions$.pipe( ofType(actions.getData), tap(_ => this.logger.debug('continue polling')), delay(8000), switchMap(_ => this.pollData()) )

问题 I am using a polling scheme in my Angular application using NgRx. To simplify things, I have something like the following... public stopPolling$ = createEffect(() => this.actions$.pipe( ofType(actions.stopPolling), tap(_ => this.isPollingActive = false), map(_ => actions.stopPolling()) ), { dispatch: false }); public continuePolling$ = createEffect(() => this.actions$.pipe( ofType(actions.getData), tap(_ => this.logger.debug('continue polling')), delay(8000), switchMap(_ => this.pollData()) )