Angular Material Autocomplete set scrolltop

Question

When opening the panel of a <mat-Autocomplete> I want to set the scrollTop to the value that is already initialised in the model. Therefore I am using to _setScrollTop method. The problem is, that the code below is not working when first opening the panel with the options, but only after I click on the input field again.

The .ts looks like this:

 export class EventInfoComponent implements OnInit {

  @Input('eventInfo') public eventInfo: SimpleEventInfoModel;
  @ViewChild(MatAutocompleteTrigger) toTimeHidden: MatAutocompleteTrigger;
  @ViewChild('toTimeComplete') toTimeAutocomplete: MatAutocomplete;

  public openAutocomplete(e): void {
    e.stopPropagation();
    this.toTimeHidden.openPanel();
    this.toTimeAutocomplete._setScrollTop(2016);
    console.log(this.toTimeAutocomplete._getScrollTop());
  }
}

And this is the HTML-snippet:

<mat-form-field appearance="outline">
    <mat-label>End Time</mat-label>
    <input matInput [required]="true" [(ngModel)]="eventInfo.toTime" 
       name="toTime" (click)="openAutocomplete($event)">
    <input type="hidden" [matAutocomplete]="toTimeComplete 
       [(ngModel)]="eventInfo.toTime" #toTimeHidden name="toTimeHidden"> 
    <mat-autocomplete #toTimeComplete="matAutocomplete">
       <mat-option *ngFor="let time of times" [value]="time"> {{time}} 
       </mat-option>
    </mat-autocomplete>
    <mat-icon matSuffix style="margin: 0 8px 0 8px">access_time</mat-icon>
</mat-form-field>

The reason I am using two different inputs is that I am using another, custom directive to format the input.

Answer 1

It seems like this is a timing problem, so I implemented a hotfix to defer the _setScrollTop until the next cycle:

setTimeout(() => { this.toTimeAutocomplete._setScrollTop(2016); }, 0);