title: onPush change detection strategy not updating values in Angular
body: <p>I'm learning how to use the onPush detection strategy. My view updates fine, but the variables on my child.component.ts values don't, but they do on the child.component.html</p>
  
  <p><strong>CHILD COMPONENT</strong></p>
  
  <pre><code>@Component({
    ....
    changeDetection: ChangeDetectionStrategy.OnPush
  })
  
  export class BdayFormComponent implements OnInit {
  
    @Input() question: Question;
    @Output() nextQuestion = new EventEmitter&lt;Question&gt;();
  
  
    nextQuestions(): void {
      ...
      this.nextQuestion.emit(......)
      console.log(this.question);
    }
  }
  </code></pre>
  
  <p>As you can see <code>nextQuestion</code>, tells the parent component to dispatch an action to get new question. I can see the next question on my HTML (let's say question #2), but when I do the <code>console.log(this.questions);</code> it prints the question #1.</p>
  
  <p><strong>PARENT COMPONENT</strong></p>
  
  <pre><code>export class BdayShellComponent implements OnInit {
    question$: Observable&lt;Question&gt;;
  
    constructor(private store: Store&lt;fromProduct.State&gt;) { }
  
    ngOnInit(): void {
      this.question$ = this.store.pipe(select(fromProduct.getCurrentQuestion));
    }
  
    setCurrentQuestion(question: Question): void {
      this.store.dispatch(new bdayActions.SetCurrentQuestion(question));
    }
  }
  </code></pre>
  
  <p><strong>PARENT COMPONENT HTML</strong></p>
  
  <pre><code>&lt;app-bday-form [question]="question$ | async"
          (nextQuestion)="setCurrentQuestion($event)"&gt;&lt;/app-bday-form&gt;
  </code></pre>