Angular 4 / RxJS, send HTTP of an array in sequence

Question

Trying to http post items of an array one after another in sequence. Knowing should use RxJS flatMap but couldn't make it work. Basically I need something like this:

item is an element of an array named items, want to go through the array and send each item.

    this.http.post(url, item)
        .subscribe(
          (response) => {
            // call the same http.post again to send the next item
          },
          (error) => {
            this.app.error(error.json() as Error); // exit
          }         
        )

Thanks for the help.

kit · Accepted Answer · 2017-05-02T17:50:54.017

2

maybe try concat

Rx.Observable.concat(...items.map(item => this.http.post(url, item)).subscribe(res => doSmthWithResponse());

edited May 02 '17 at 17:50

answered May 01 '17 at 21:12

kit

4,890
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Thank you for the response. "ng build" complains "Property 'subscribe' does not exist on type 'Observable[]'." on following code: Observable.concat(items.map( (item:Item) => this.http.post(url, item)) .subscribe(response => this.doSomething() ) ); – brewphone May 02 '17 at 01:55
you forgot to add "..." (spread operator) in front of items.map. try Observable.concat(...items.map( (item:Item) => this.http.post(url, item)) .subscribe(response => this.doSomething() ) ); – kit May 02 '17 at 07:20
Really didn't know spread operator, thank you. But got exactly the same error with this code: Observable.concat(...items.map( (item:Item) => this.http.post(url, item)).subscribe(response => this.doSomething() ) ); Should the issue be in my import: import {Observable} from 'rxjs/Observable'; import 'rxjs/add/operator/map'; import 'rxjs/add/observable/concat'; Any other import? Thank you very much. – brewphone May 02 '17 at 13:51
you miss one closing parentheses before subscribe, try this: Observable.concat(...items.map( (item:Item) => this.http.post(url, item))).subscribe(response => this.doSomething() ) ); – kit May 02 '17 at 17:49

score 0 · Answer 2 · answered May 01 '17 at 21:05

0

  this.http.post(url, item).map(res => res.json())
            switchMap(this.http.post(url1, item).map(res => res.json()))

answered May 01 '17 at 21:05

Julia Passynkova

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score 0 · Answer 3 · answered Jul 21 '17 at 11:31

You can try using from and flatmap

Observable.from(items)
    .flatMap(item => this.http.post(url, item))
    .subscribe({
        res => console.log("your response"),
        error => console.log("your error"),
        () => doSomethingAtEnd()
    });

Angular 4 / RxJS, send HTTP of an array in sequence

3 Answers3