I have implemented http pooling in Angular app with IntervalObservable and startWith to start instantly. I wanted to know does IntervalObservable wait until initial/previous call finished streaming data? Is there a better way to implement data poolingin Angular app.
Ex from service.ts
getRecordsList() {
return IntervalObservable
.create(15000)
.startWith(0)
.flatMap((r) => this.http
.post(`http://services.com/restful/recordService/getRecordsList`, body, {
headers: new HttpHeaders().set('Content-Type', 'application/json')
}))
.shareReplay()
.catch(this.handleError);
}
Ex from component.ts
ngOnInit() {
this.service.getRecordsList()
.subscribe(
(recordList) => {
this.recordResponse = recordList;
},
error => { console.log },
() => console.log("HTTP Observable getRecordsList() completed...")
);
}
I have used Angular httClient and I hope this doesn't matter anyhow.
Here's something that might help you:
const { Observable } = Rx;
// HTTP MOCK
const http = {
post: () => Observable.of('some response').delay(1000)
}
// SERVICE PART
const polling$ = Observable.timer(0, 5000);
const myRequest$ = polling$
.do(() => console.log(`launching a new request...`))
.switchMap(() => http.post('some-url'));
// COMPONENT PART
myRequest$
.do(res => console.log(`Response: ${res}`))
.subscribe();
And a working Plunkr: https://plnkr.co/edit/BCTmlOv6FarNN1iUmMcA?p=preview
Your code seems reasonable to me. Here is a similar code that uses IntervalObservable
to pool the server until some condition is met.
import { Component } from '@angular/core';
import { Http } from '@angular/http';
import { IntervalObservable } from 'rxjs/observable/IntervalObservable';
import 'rxjs/add/operator/takeWhile';
import 'rxjs/add/operator/startWith';
@Component({
selector: 'my-angular2-app',
templateUrl: './tool-component.html',
styleUrls: ['./tool-component.css']
})
export class ToolComponent {
private _APIBaseURL = 'https://api.app.io';
private _autoRefresh: boolean = true;
private _downloadLink: string = ""
private _fileID: string = ""
constructor(private _http: Http) { }
// add code here
// ...
getDownloadLink() {
this._autoRefresh = true;
this._downloadLink = "";
IntervalObservable
.create(10000)
.startWith(0)
.takeWhile(() => this._autoRefresh)
.subscribe(() => {
this._http.get(`${this._APIBaseURL}/rocess?file-name=${this._fileID}`)
.subscribe(data => {
let idata = data.json();
if (idata['current_status'] == "done") {
this._downloadLink = idata.url;
this._autoRefresh = false;
}
})
}
)
}
}
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