如何在我的angular2 +代码中与ngOnChanges合并

Question

我的应用程序中有一个下拉菜单。这是ng-multiselect-drop-down。它有一个错误。在这里，我能够选择值，并且它们会正确显示，但是当我取消选择一个值时，它不会从值列表中减去。所以我发现，我们可以使用ngOnChanges。但是，我无法执行。 我实现的代码是-

app.component.ts

export class NodeVennComponent implements OnInit, OnChanges {
@Input() selectedItemsSelected:  any[];

  ngOnChanges(changeRecord: SimpleChanges) {

if(changeRecord['selectedItemsSelected'] !== undefined){
  this.selectedItemsSelected = changeRecord['selectedItemsSelected'].currentValue;
  console.log("this.selectedItemsSelected, ngOnChanges = ", this.selectedItemsSelected)
}

    console.log('SimpleChanges It works!');
  }


//code
}

app.component.html

<div >
    <br>
    <br>
    <div>
        <p>Select {{menuItem}} </p>
        <p style="width:50%">
            <ng-multiselect-dropdown [placeholder]="'Select  API Object'" [data]="dropdownListSelected" [(ngModel)]="selectedItemsSelected"
                [settings]="dropdownSettingsSelected" (onSelect)="onItemSelectSelected($event)" (onSelectAll)="onSelectAllSelected($event)">
            </ng-multiselect-dropdown>

        </p>
    </div>
    <!-- margin-left:550px -->

   <div *ngIf="apiSelect">
    <button class="btn btn-dark" (click)="nodalGraphSelectSingle()" style=" margin: auto; display:block"> Select API Object</button>
    <br>
    <br>
</div> 
</div>

图像显示我选择了许多值，然后取消选择它们，但this.selectedItems的值仍然是这些多个值。请帮助解析并选择确切的值数。