title: Multi-select showing null value in primeng on assigning value programmatically in typescript
body: <p>I am using angular 2 and primeng to show a multiselect dropdown.</p>
  
  <pre><code>  &lt;div class="ui-g-9"&gt;
      &lt;p-multiSelect [options]="groupsDropDown"  [(ngModel)]="selectedGroups" [style]="{'width':'50%'}"&gt;
      &lt;/p-multiSelect&gt;
       &lt;/div&gt;
  </code></pre>
  
  <p>Now in typescript on a function call am reassigning the value.</p>
  
  <pre><code>editEmail(publishingGroup) {
      this.selectedGroups = publishingGroup.groups;
  }
  </code></pre>
  
  <p>On this the Multiselect dropdown label shows the selected value but the option remains unchecked as shown in the picture.
  <a href="https://i.stack.imgur.com/e47cn.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/e47cn.png" alt="enter image description here"></a></p>
  
  <p>Also the label value gets null on selection of another option as shown below,here the "developer" is turned as null somehow.</p>
  
  <p><a href="https://i.stack.imgur.com/zjksf.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/zjksf.png" alt="enter image description here"></a></p>