如何取消角度2的 HTTPRequest？

如何取消角度2的 HTTPRequest？

我只知道如何拒绝请求的承诺。

return new Promise((resolve, reject) => {
this.currentLoading.set(url, {resolve, reject});


this.http.get(url, {headers: reqHeaders})
.subscribe(
(res) => {
res = res.json();


this.currentLoading.delete(url);
this.cache.set(url, res);


resolve(res);
}
);
});
97834 次浏览
小开
最佳答案

You can call unsubscribe

let sub = this.http.get(url, {headers: reqHeaders})
.subscribe(
(res) => {
res = res.json();


this.currentLoading.delete(url);
this.cache.set(url, res);


resolve(res);
}
);


sub.unsubscribe();

More info here: http://www.syntaxsuccess.com/viewarticle/angular-2.0-and-http

小开

You can use the following simple solution:

if ( this.subscription ) {
this.subscription.unsubscribe();
}
this.subscription = this.http.get( 'awesomeApi' )
.subscribe((res)=> {
// your awesome code..
})
小开

A little late for the party, but here is my take:

import { Injectable } from '@angular/core'
import { Http } from '@angular/http'
import { Observable } from 'rxjs/Observable'
import { Subscriber } from 'rxjs/Subscriber'


@Injectable ()
export class SomeHttpServiceService {
private subscriber: Subscriber<any>
constructor(private http: Http){ }


public cancelableRequest() {
let o = new Observable(obs => subscriber = obs)
return this.http.get('someurl').takeUntil(o)
.toPromise() //I dont like observables
.then(res => {
o.unsubscribe
return res
})
}
public cancelRequest() {
subscriber.error('whatever')
}
}

This allows you to manually cancel a request. I sometimes end up with an observable or promise that will make changes to a result on the page. If the request was initiated automatically (user didn't type anyting in a field for x millis) being able to abort the request is nice (user is suddenly typing something again)...

takeUntil should also work with a simple timeout (Observable.timer) if that is what you are looking for https://www.learnrxjs.io/learn-rxjs/operators/filtering/takeuntil

小开

You can use SwitchMap on the observable which will cancel any previous request's responses and only request the latest:

https://www.learnrxjs.io/operators/transformation/switchmap.html

小开

Use switchMap [docs], which will cancel all in-flight requests and use only the latest.

get(endpoint: string): Observable<any> {
const headers: Observable<{url: string, headers: HttpHeaders}> = this.getConfig();
return headers.pipe(
switchMap(obj => this.http.get(`${obj.url}${endpoint}`, { headers: obj.headers, params: params }) ),
shareReplay(1)
);
}

shareReplay will emit the latest value for any late subscribers.

小开

This is a great thread, and I have a little more info to provide. I have an API call that could potentially go on for a very long time. So I needed the previous request to cancel with a timeout. I just figured out today that I can add a timeout operator to the pipe function. Once the timeout completes its count, that will cancel the previous HTTP request.

Example...

return this.exampleHttpRequest()
.pipe(
timeout(3000),
catchError(err => console.log(error)
)

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