title: How to subscribe on variable in Angular 2?
body: <p>I have got an variable in component was declared as:</p>
  
  <pre><code>public filter: Filter = {};
  </code></pre>
  
  <p>In template I bind this object like as:</p>
  
  <pre><code>&lt;input [ngModel]="filter.name" value=""/&gt;
  &lt;input [ngModel]="filter.secondname" value=""/&gt;
  </code></pre>
  
  <p>How to listen changes this variable(object) <code>filter</code>?</p>
  
  <p>I mean something like this:</p>
  
  <pre><code>this.filter.subscribe().then(changes =&gt; { // Call method here })
  </code></pre>
  
  <p>PS:
  I dont want to use event <code>ngChange=""</code> for each input elements</p>