rxjs

问题 I am trying to do multiple HTTP requests in angular using forkjoin.But when I subscribe to Observable it doest not give any response. let data = this.email.map((email) => this.get_student_service.get_student_by_email_id(email) ); forkJoin([data]).subscribe((res) => { console.log(res); }); console.log('Execute'); Here is my service get_student_by_email_id(email) { return this.fire_store .collection('User', (ref) => ref.where('email', '==', email)) .valueChanges(); } 回答1: Ok, if you're getting

问题 My service returns object with events and count properties. Right now I need to do two requests. First to get events and second to get events count. I'd like to use Observables in component and async pipe in the template. I know how to achieve it subscribing to the service in the component, but I'd like to understand how to map both events and count to an observables with one request. What RxJs operator should I use ? import { Component, OnInit } from '@angular/core'; import { Event } from '.

问题 My service returns object with events and count properties. Right now I need to do two requests. First to get events and second to get events count. I'd like to use Observables in component and async pipe in the template. I know how to achieve it subscribing to the service in the component, but I'd like to understand how to map both events and count to an observables with one request. What RxJs operator should I use ? import { Component, OnInit } from '@angular/core'; import { Event } from '.

问题 My code: ngOnInit() { this.activatedRoute.params.subscribe((params: Params) => { // do stuff }) this.activatedRoute.data.subscribe((data: any) => { // do stuff }) } My question is ... do I need to unsubscribe from these in ngOnDestroy? As a matter of habit I always unsub but not sure if it is necessary here. thanks 回答1: No, you don't need to unsubscribe from route observables From the Documentation When subscribing to an observable in a component, you almost always arrange to unsubscribe when

问题 My code: ngOnInit() { this.activatedRoute.params.subscribe((params: Params) => { // do stuff }) this.activatedRoute.data.subscribe((data: any) => { // do stuff }) } My question is ... do I need to unsubscribe from these in ngOnDestroy? As a matter of habit I always unsub but not sure if it is necessary here. thanks 回答1: No, you don't need to unsubscribe from route observables From the Documentation When subscribing to an observable in a component, you almost always arrange to unsubscribe when

问题 My code: ngOnInit() { this.activatedRoute.params.subscribe((params: Params) => { // do stuff }) this.activatedRoute.data.subscribe((data: any) => { // do stuff }) } My question is ... do I need to unsubscribe from these in ngOnDestroy? As a matter of habit I always unsub but not sure if it is necessary here. thanks 回答1: No, you don't need to unsubscribe from route observables From the Documentation When subscribing to an observable in a component, you almost always arrange to unsubscribe when

问题 I have some events that I'd like to buffer but I'd like to buffer only after the first element. [------bufferTime------] Input over time: [1, 2, 3, -------------|---4, 5, 6 ----------------] Output over time: [1]-----------------[2,3]---[4]------------------[5,6] is there a way to do this? 回答1: I think this can be solved by dividing your stream into two, firstValue$ and afterFirstValue$, and then merging them. import { merge } from 'rxjs'; import { take, skip, bufferTime } from 'rxjs

问题 I have a statistics application. On the left side of my page I have list of themes, on the top - list of groups. The main part contains statistics items related to both theme and group. Also I have several services which provide business logic for my application. For simplicity let's talk about three of them: ThemeSerivce, GroupService and StatisticsService . End users could manipulate lists of themes and groups (add or remove items) and I have to recalculate statistics after each change. In

问题 Use case: Call a function every minute (60000 ms) that dispatches store action to fetch lastUpdated status of items, which upon response and filtering, updates the store, and updated store is read as an observable and displayed in the view). This needs to happen for as long as the web app is open (so indefinitely). Currently, I'm using this: this.refreshDate = window.setInterval( () => this.store.dispatch(new FetchLastUpdate()) , 60000); And when view is destroyed/dismounted, I delete the

问题 Use case: Call a function every minute (60000 ms) that dispatches store action to fetch lastUpdated status of items, which upon response and filtering, updates the store, and updated store is read as an observable and displayed in the view). This needs to happen for as long as the web app is open (so indefinitely). Currently, I'm using this: this.refreshDate = window.setInterval( () => this.store.dispatch(new FetchLastUpdate()) , 60000); And when view is destroyed/dismounted, I delete the