title: How can I use the complete() when my asyn operation is completed?
body: <p>My Code:</p>
  
  <h2>.ts</h2>
  
  <pre><code>export class HomePage implements OnInit {
    datas: FirebaseListObservable&lt;any[]&gt;;
    // datas: FirebaseListObservable&lt;Item[]&gt;;
  
    constructor(public navCtrl: NavController, public authData: AuthData, public af: AngularFire) { }
    ngOnInit() {
  
      this.datas = this.af.database.list('/datas');
      //console.log('datas'+JSON.stringify(this.datas));
  
    }
  
    loadData(refresher?: any) {
      callToProviderApi().subscribe(newData =&gt; {
        this.datas = newData;
      }, err =&gt; console.log(err),
        () =&gt;if(refresher)
          refresher.complete());//call complete on subscribe complete
    }
  
    doRefresh(datas) {
      this.loadData(datas);
    }
  </code></pre>
  
  <h2>.html</h2>
  
  <pre><code>&lt;ion-refresher (ionRefresh)="doRefresh()"&gt;
          &lt;ion-refresher-content&gt;
            pullingIcon="arrow-dropdown"
          &lt;/ion-refresher-content&gt;
        &lt;ion-list&gt;
          &lt;ion-item *ngFor="let data of datas | async" class="pqr"&gt;
            &lt;ion-thumbnail item-left&gt;
              &lt;img src="assets/image/{{data.imageName}}"&gt;
            &lt;/ion-thumbnail&gt;
            {{data.Comp}}&lt;br&gt; 
            {{data.Demand}}&lt;br&gt;
            &lt;p&gt; {{data.Desig}}&lt;br&gt;&lt;/p&gt;
            {{data.Place}}&lt;br&gt;
             {{data.when}}&lt;br&gt;
          &lt;/ion-item&gt;
        &lt;/ion-list&gt;
        &lt;/ion-refresher&gt;
  </code></pre>
  
  <p>I have not understood the following points:</p>
  
  <ol>
  <li>As dataset is asyn, Can't it be viewed in the console?</li>
  <li>when I ran this code, the following error is displayed as runtime
  error: <code>Cannot read property 'complete' of undefined</code>.</li>
  <li>When I navigate to the page where my content is shown, it does not
  show the content which is already present, as well as the refresher
  keeps on starting.</li>
  </ol>
  
  <p>Note: Please let me know if more inputs and screenshots should be needed.</p>