title: Get child of FirebaseObjectObservable - Angularfire2
body: <p>Is it possible to target a child of a FirebaseObjectObservable?
  Please check <code>RcTestAppComponent.save()</code> from below(commented lines).</p>
  
  <p>Example from: <a href="https://github.com/angular/angularfire2/blob/master/docs/3-retrieving-data-as-lists.md" rel="nofollow">https://github.com/angular/angularfire2/blob/master/docs/3-retrieving-data-as-lists.md</a></p>
  
  <pre><code>import { Component } from '@angular/core';
  import { AngularFire, FirebaseObjectObservable } from 'angularfire2';
  
  @Component({
    moduleId: module.id,
    selector: 'app',
    template: `
    &lt;h1&gt;{{ item | async | json }}&lt;/h1&gt;
    &lt;input type="text" #newname placeholder="Name" /&gt;
    &lt;input type="text" #newsize placeholder="Size" /&gt;
    &lt;br /&gt;
    &lt;button (click)="save(newname.value)"&gt;Set Name&lt;/button&gt;
    &lt;button (click)="update(newsize.value)"&gt;Update Size&lt;/button&gt;
    &lt;button (click)="delete()"&gt;Delete&lt;/button&gt;
    `,
  })
  export class RcTestAppComponent {
    item: FirebaseObjectObservable&lt;any&gt;;
    constructor(af: AngularFire) {
      this.item = af.database.object('/item');
    }
    save(newName: string) {
      this.item.set({ name: newName });
      /*
        // can I do somethin like this:
        let index = 2;
        this.item.child(index).set({ name: newName });
        // index is a dynamic number;
  
        // when I use .child() on this.item, i receive a error: 
        // TypeError this.item.child is not a function
      */
  
    }
    update(newSize: string) {
      this.item.update({ size: newSize });
    }
    delete() {
      this.item.remove();
    }
  }
  </code></pre>
  
  <p>Thank you</p>