title: How to trigger change detection when array object is modified?
body: <p>In my angular4 app i have a component with a *ngFor directive based in a array:</p>
  
  <pre><code> &lt;div *ngFor="let person of persons"&gt;
     {{person.name}}
     {{person.car}}
   &lt;/div&gt;
  </code></pre>
  
  <p>In the other part of the component im able to delete a car, so in the subscribe of the <code>deleteCar()</code> method i update the <code>persons</code> array to:</p>
  
  <pre><code> deleteCar(car) {
     this.carService.deleteCar(car).subscribe(() =&gt;  {
     this.persons.filter(obj =&gt; obj.car == car.name)
                 .forEach(i =&gt; i.car = null);
     }
   }
  </code></pre>
  
  <p>The problem is that the *ngFor loop is not triggered when i modify a existing person object in the persons array. How to solve this?</p>