title: ngFor list do not print empty value
body: <p>I receive data (for card) which I further populate as a list:</p>
  
  <pre><code>[{"id":20,"responsibilities":[{"id":39,"attribute":"Name","action":"","card":20},{"id":40,"attribute":"ISBN","action":"","card":20},{"id":41,"attribute":"Genre","action":"","card":20},{"id":42,"attribute":"","action":"Purchase","card":20}],"collaborators":[],"thing":"Book"}] 
  </code></pre>
  
  <p>I am populating two lists as following:</p>
  
  <pre><code>   &lt;h6&gt;Attributes&lt;/h6&gt;
     &lt;ul&gt;
       &lt;li *ngFor="let item of card.responsibilities"&gt;
        &lt;div *ngIf="item.attribute"&gt;{{item.attribute}}&lt;/div&gt;
      &lt;/li&gt;
     &lt;/ul&gt;
     &lt;h6&gt;Actions&lt;/h6&gt;
     &lt;ul&gt;
       &lt;li *ngFor="let item of card.responsibilities"&gt;
         &lt;div *ngIf="item.action"&gt;{{item.action}}&lt;/div&gt;
       &lt;/li&gt;
     &lt;/ul&gt;
   &lt;/ion-col&gt;
  </code></pre>
  
  <p>which looks like following:</p>
  
  <p><a href="https://i.stack.imgur.com/RMNPq.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/RMNPq.png" alt="enter image description here"></a></p>
  
  <p>I do not want to print items which have empty values i.e. in the first list if attribute is empty string "" or in the second list if the action is an empty string "". Right now those values are also printed in both the lists.</p>
  
  <p>How to fix this? *ngIf as I tried has no effect.</p>