CODEWITHSUNDEEP
javascriptangularrxjs
provoter33
provoter33

Reputation: 119

How get data from server? Use interval operator

I get data from remote server. CORS is configured. I use interval() operator form RXJS library.

Component:

import { Observable } from 'rxjs/Observable';
import 'rxjs/add/observable/interval';
import 'rxjs/add/operator/switchMap';

private getUserTasks(userId): void {
    Observable
      .interval(5000)
      .switchMap(() => this.tasksService.getUserTasks(userId))
      .subscribe(
          data => {
              this.userTasks = JSON.parse(data);                 
              console.log('userTasks', this.userTasks);
          }
      )
};

Service return observable object:

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { Observable } from 'rxjs/Observable';

@Injectable()
export class TasksService {
  constructor(private http: HttpClient) { };
  getUserTasks(userId): Observable<any> {
    return this.http.get('http://blabla.com/app_tasks/user_tasks?user_id=' + userId);
  };
}

But after the user enters the page, he waits 5 seconds (and looks at the white screen). I need to send a request immediately after the page is loaded. And then every 5 seconds the request was repeated

Upvotes: 0

Views: 166

Answers (1)

LLai
LLai

Reputation: 13396

You can use startWith to have the sequence emit an initial value

private getUserTasks(userId): void {
    Observable
        .interval(5000)
        .startWith(0)
        .switchMap(() => this.tasksService.getUserTasks(userId))
            .subscribe(data => {
                this.userTasks = JSON.parse(data);                 
                console.log('userTasks', this.userTasks);
            })
};

Upvotes: 2

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