title: conditional data binding in angular2
body: <p>below is my code to display images from database .</p>
  
  <pre><code>   &lt;div *ngfor='let pad of pictures' class=""&gt;
        &lt;img class="activator"src="imagepas/{{pad.picturefirst}}"&gt;
      &lt;/div&gt;
  </code></pre>
  
  <p>in database sometime there will not be image every time so i want to display a default image, image is for this case alone but there will situations when i want to do some conditional calculation before displaying data. i read about ngswitch but how can i put condition like <code>pad.picturefirst==null</code> its not working that way . please help</p>